DRAS-25-3304-MIL-STD-3071-Change2-Draft-20250929_withBanners2-1.pdf

MIL-STD-3071

w/CHANGE 2

DRAFT

SUPERSEDING

MIL-STD-3071

w/CHANGE 1 08 July 2024

DEPARTMENT OF DEFENSE

INTERFACE STANDARD

TACTICAL MICROGRID

COMMUNICATIONS AND CONTROL

AMSC N/A FSC 6115

METRIC NOTE: This draft dated 29 September 2025 prepared by U.S. Army DEVCOM C5ISR Center has not been approved and is subject to modification. DO NOT USE FOR

ACQUISITION PURPOSES.

APPROVED FOR PUBLIC RELEASE

w/ CHANGE 2 DRAFT 29 Sep 2025 ii

FOREWORD

This standard is approved for use by all Departments and Agencies of the Department of

Defense (DoD) This standard establishes criteria to enable the interoperability of hardware and software necessary to operate a tactical microgrid on the battlefield with respect to the design, intelligent control, stability and performance, security, safety of personnel, and the protection of the tactical microgrid system and equipment.

This standard defines the tactical microgrid architecture using open standards to support a modular, highly cohesive system structure in order to leverage the collaborative innovation of industry, academia, and government participants along with stakeholders.

This document is intended to be free of Essential Patent Claims. Although development of this standard was made with the active participation of the Private Sector, non-government contributors have certified that they have declared all essential patent claims found in this standard.

Comments, suggestions, or questions on this document should be emailed to usarmy.apg.devcom-c5isr.mbx.standardization-crx@army.mil. Since contact information can change, you may want to verify the currency of this address information using the ASSIST Online database at https://assist.dla.mil.

A TMS website connects the Government and the public for information sharing/dissemination on MIL-STD-3071. It will host the current published MIL-STD, upcoming approved changes to the standard, support resources, and provides announcement space for important TMS topics. The website can be found at https://go.mil/tms.

APPROVED FOR PUBLIC RELEASE

APPROVED FOR PUBLIC RELEASE

mailto:usarmy.apg.devcom-c5isr.mbx.standardization-crx@army.mil https://assist.dla.mil/ https://go.mil/tms iii

SUMMARY OF CHANGE 2 MODIFICATIONS

1. Improved Object Management Group Data Distribution Service (OMG DDS) network interoperability requirements.

2. Introduced data model version 2.0.3. All changes are backwards compatible with versions 2.0.1 and 2.0.2.

3. Added machine readable files for topic definition figures and tables.

4. Added optional specifications for DDS Security integration.

5. Added an improved CHANGE HISTORY at the end of the Appendix.

iv

Table of Contents

1. SCOPE

1.1. Scope

1.2. Purpose

1.3. Application

1.4. Classification

1.5. Limitations

2. APPLICABLE DOCUMENTS

2.1. General

2.2. Government documents

2.2.1. Specifications, standards, and handbooks

2.2.2. Other Government documents, drawings, and publications

2.3. Non-Government Publications

2.4. Order of Precedence

3. DEFINITIONS

3.1. Acronyms

3.2. Definitions

3.2.1. Automatic Voltage Regulator (AVR)

3.2.2. Backwards compatibility

3.2.3. Command

3.2.4. Configuration

3.2.5. Device

3.2.6. Distribution

3.2.7. Essential patent

3.2.8. Exciter

3.2.9. Fingerprint

3.2.10. Generating source

3.2.11. Grid

3.2.12. Interconnection

3.2.13. Interface

3.2.14. Interoperability

3.2.15. Inverter

3.2.16. Legacy equipment

3.2.17. Load

v

3.2.18. Load shedding

3.2.19. Operator

3.2.20. Power Device

3.2.21. Open standard

3.2.22. Performance

3.2.23. Point of Connection (POC)

3.2.24. Ring-bus off-line

3.2.25. Setting

3.2.26. Source (SRC)

3.2.27. Storage device

3.2.28. Tactical

3.2.29. Tactical Microgrid (TMG)

3.2.30. Tactical Microgrid Controller (TMC)

3.2.31. User

3.2.32. Warfighter

4. GENERAL REQUIREMENTS

4.1. General

4.2. Types of Tactical Microgrid Equipment

4.2.1. Type I – Power Generation Sources

4.2.2. Type II – Energy Storage Systems

4.2.3. Type III – Feeder Systems

4.2.4. Type IV – Distribution Systems

4.2.5. Type V – Control Systems

4.2.6. Type VI – Loads

4.2.7. Type VII – Power Conversion

4.3. Interoperability

4.4. Standalone Use

4.4.1. Type I Power Generation Sources and Type II Energy Storage Equipment

4.4.2. Type III Feeder and Type IV Distribution Systems Equipment

4.5. Degraded Operation

4.6. Monitoring and Control

4.7. Cybersecurity

4.7.1. Risk Management Framework (RMF)

4.7.2. Operational Resilience

vi

4.7.3. Access to firmware/software

4.8. Tactical Microgrid Architecture

4.8.1. Common Microgrid Control System

4.8.2. Common Microgrid Monitoring System

4.8.3. Levels of Control

4.8.4. Tactical Microgrid Control (TMC) Redundancy

4.8.5. Communications Architecture

4.9. Data Model

4.9.1. Device Identity

4.9.2. Device Roles

4.9.3. Platforms

4.9.4. Data flows

4.9.5. Publishers and Subscribers

4.9.6. Topic and Message Flow

4.9.7. Data Types

4.9.8. Data Flow Patterns

4.9.9. Instances

4.9.10. Timing

5. DETAILED REQUIREMENTS

5.1. Safety

5.2. Human Engineering

5.3. TMG Equipment Roles and Responsibilities

5.3.1. Type I – Power Sources

5.3.2. Type II – Energy Storage

5.3.3. Type III – Feeder Systems

5.3.4. Type IV – Distribution Systems

5.3.5. Type V – Control Systems

5.3.6. Type VI – Loads

5.3.7. Type VII – Power Conversion

5.4. Communications Interface

5.4.1. Application Layer

5.4.2. Presentation Layer

5.4.3. Session Layer

5.4.4. Transport Layer

vii

5.4.5. Network Layer

5.4.6. Physical Layer

6. NOTES

6.1. Intended Use

6.2. Acquisition requirements

6.3. Tailoring guidance

6.4. Subject term (key word) Listing

6.5. Changes from previous issue

APPENDIX (DATA MODEL)

CONCLUDING MATERIAL

1. SCOPE.

1.1.Scope. This standard establishes the communication and control interface requirements for Tactical Microgrids (TMGs) to enable TMG components to operate as a single entity to provide electricity in a tactical environment. This standard defines the component interfaces of the hardware and software necessary to provide intelligent control, power quality, electrical stability, electrical performance, safety of personnel, security, and protection.

A tactical microgrid is a warfighter-operated and maintained power system consisting of a mobile, flexible group of interconnected power generation sources, distribution, energy storage, and load devices that act as a single, controllable system to provide electricity on the battlefield.

1.2.Purpose. The purpose of this DOD standard is to define an open communication and control architecture for TMGs to facilitate:

a. Interoperability between manufacturers of tactical microgrid components Safety of personnel and equipment Backwards compatibility with legacy equipment wherever possible Security of the tactical microgrid communication network and controllers Reduction of procurement, operational, sustainment, and maintenance costs

1.3.Application. This standard is applicable to tactical microgrid systems, subsystems, and individual equipment. While this standard provides interoperability and design criteria guidance, it is not intended to limit innovation in the design or selection of specific hardware, software, materials, and processes.

1.4.Classification. The tactical microgrids are made up of the following types of equipment:

Table 1-1 Types of Equipment in a Tactical Microgrid

Types of Equipment in a Tactical Microgrid Type I Power Generation Sources (e.g. Engine-Generator sets, Solar, Wind, etc.)

Type II Energy Storage Systems, (e.g. batteries, capacitors, etc.)

Type III Feeder Systems (e.g. 3 phase inputs with 3 phase outputs) Type IV Distribution Systems, (e.g. 1 or 3 phase inputs with 1 phase outputs) Type V Control Systems w/ Communications and cabling Type VI Loads (e.g. Improved Environmental Control Units) Type VII Power Conversion

1.5.Limitations. This document does not define test procedures that verify compliance with this standard. This document is not to be referenced as the sole source for cybersecurity requirements.

2. APPLICABLE DOCUMENTS

2.1.General. The documents listed in this section are specified in sections 3, 4, or 5 of this standard. This section does not include documents cited in other sections of this standard or recommended for additional information or as examples. While every effort has been made to ensure the completeness of this list, document users are cautioned that they must meet all specified requirements of documents cited in sections 3, 4, or 5 of this standard, whether or not they are listed.

2.2.Government documents.

2.2.1. Specifications, standards, and handbooks. The following specifications, standards, and handbooks form a part of this document to the extent specified herein. Unless otherwise specified, the issues of these documents are those cited in the solicitation or contract.

DEPARTMENT OF DEFENSE STANDARDS

MIL-STD-882 System Safety

MIL-STD-1332

Definitions of Tactical, Prime, Precise, and Utility Terminologies for Classification of the DOD Mobile Electric Power Engine Generator Set Family

MIL-STD-1472 Human Engineering

(Copies of these documents are available online at https://quicksearch.dla.mil.)

2.2.2. Other Government documents, drawings, and publications. The following other Government documents, drawings, and publications form a part of this document to the extent specified herein. Unless otherwise specified, the issues of these documents are those cited in the solicitation or contract.

ARMY REGULATIONS

AR 385-10 The Army Safety Program

(Copies can be obtained at https://armypubs.army.mil/ProductMaps/PubForm/AR.aspx.)

DOD ISSUANCES

DODI 8500.01 Cybersecurity

(Copies can be obtained at https://www.esd.whs.mil/DD/DoD-Issuances/.)

NATIONAL INSTITUTES OF SCIENCE AND TECHNOLOGY

NIST SP 800-39 Managing Information Security Risk: Organization, Mission, and Information System View

NIST SP 800-53 Rev. 5 Security and Privacy Controls for Information Systems and Organizations

APPROVED FOR PUBLIC RELEASE

APPROVED FOR PUBLIC RELEASE

https://quicksearch.dla.mil/ https://armypubs.army.mil/ProductMaps/PubForm/AR.aspx https://www.esd.whs.mil/DD/DoD-Issuances/

NIST SP 800-82 Rev. 2 Guide to Industrial Control Systems (ICS) Security

(Copies can be obtained at https://www.nist.gov/.)

2.3. Non-Government Publications. The following documents form a part of this document to the extent specified herein. Unless otherwise specified, the issues of these documents are those cited in the solicitation or contract.

INSTITUTE OF ELECTRICAL AND ELECTRONIC ENGINEERS (IEEE)

IEEE 802.3 Standard for Ethernet

(Copies can be obtained at https://www.ieee.org/)

INTERNATIONAL ORGANIZATION FOR STANDARDIZATION

ISO/IEC 7498-1 Information technology – Open Systems Interconnection –

Basic Reference Model: The Basic Model ISO/IEC 7498-3 Information technology – Open Systems Interconnection –

Basic Reference Model: The Basic Model Naming and Addressing

ISO/IEC 7498-4 Information Processing Systems- Open Systems Interconnection – Basic Reference Model: Part 4 Management Framework

(Copies can be obtained at https://www.iso.org)

INTERNET ENGINEERING TASK FORCE

RFC-8200 Internet Protocol, Version 6 (IPv6) Specification

(Copies can be obtained at https://www.ietf.org/)

NATIONAL FIRE PROTECTION ASSOCIATION (NFPA)

NFPA-70 National Electrical Code NFPA-70E Standard for Electrical Safety in the Workplace

(Copies can be obtained at https://nfpa.org/)

2.4.Order of Precedence. Unless otherwise noted herein or in the contract, in the event of a conflict between the text of this document and the references cited herein, the text of this

APPROVED FOR PUBLIC RELEASE

APPROVED FOR PUBLIC RELEASE

https://www.nist.gov/ https://www.ieee.org/ https://www.iso.org/ https://www.ietf.org/ https://nfpa.org/ document takes precedence. Nothing in this document, however, supersedes applicable laws and regulations unless a specific exemption has been obtained.

3. DEFINITIONS.

3.1.Acronyms.

ACRONYM DEFINITION

AC Alternating Current AN Application Note

ANSI/NEMA American National Standards Institute / National Electrical Manufacturers Association

API Application Programming Interface AR Army Regulation DC Direct Current

DDS Data Distribution Service DER Distributed Energy Resource DOD Department of Defense DODI Department of Defense Instruction ECU Environmental Control Unit EIO Energy Informed Operations

GCRA Generic Cell Rate Algorithm IEC International Electrotechnical Commission

IEEE Institute of Electrical and Electronics Engineers IETF Internet Engineering Task Force IoT Internet of Things IP Internet Protocol

IPv6 Internet Protocol Version 6 ISO International Organization for Standardization IT Information Technology

JSON JavaScript Object Notation MBS Maximum Burst Size MC Microgrid Controller

MIL-STD-XXX Defense Standard MMC Master Microgrid Controller

ACRONYM DEFINITION

NEC National Electrical Code

NFPA National Fire Protection Association NIST National Institute of Standards and Technology NSN National Stock Number OMG Object Management Group

OpenFMB™ Open Field Message Bus OSI Open Systems Interconnection OT Operational Technology

PCR Peak Cell Rate PTP Precision Time Protocol QoS Quality of Service RFC Request For Comment RMF Risk Management Framework RMS Root Mean Squared ROM Read Only Memory RoT Root of Trust

SDLC System Development Lifecycle SP Special Publication TM Technical Manual TLS Transport Layer Security TMG Tactical Microgrid TMC Tactical Microgrid Controller TMS Tactical Microgrid Standard TPM Trusted Platform Module UDP User Datagram Protocol UI User Interface

VAC Volts AC XML Extensible Markup Language

3.2.Definitions

3.2.1. Automatic Voltage Regulator (AVR). A device that automatically adjusts the synchronous generator’s excitation to regulate the voltage output to either a predetermined level or based on a stable reference, for example, the sinusoidal output Root Mean Squared (RMS) voltage.

3.2.2. Backwards compatibility. The ability of a system or component to operate with previously-fielded systems or components of the system.

3.2.3. Command. An action with an immediate effect that the system must attempt to execute.

A failure results in an error.

3.2.4. Configuration. A collection of devices and connections that complete a TMG system.

3.2.5. Device. A standalone component that is part of the TMG system, including generating sources, Tactical Microgrid Controller (TMC), distribution, storage, and loads.

3.2.6. Distribution. All the equipment necessary to distribute power from the sources to the loads, including protective devices, boxes, and cabling. Distribution equipment include both Type III Feeder Systems and Type IV Distribution Systems.

3.2.7. Essential patent. A patent required to be obtained in order to produce a standard compliant product.

3.2.8. Exciter. A device that provides electric current to produce the rotor’s magnetic field in a generator, for example, a battery or small generator.

3.2.9. Fingerprint. A data type that assigns a unique identity to each TMS device, associated with a single specific device role.

3.2.10. Generating source. Equipment which consumes fuel to provide power to the TMG, typically synchronous diesel generators.

3.2.11. Grid. General term for a system of components connected together. In this standard, grid refers to either a Utility Power Grid or a Microgrid.

3.2.12. Interconnection. Process of connecting military generation and distribution equipment to a powered or un-powered Power System.

3.2.13. Interface. The point where two systems meet and interact.

3.2.14. Interoperability. The ability to act coherently, effectively, and efficiently to achieve tactical, operational, and strategic objectives. The devices must communicate, provide, and use services and information between systems, regardless of manufacturer or version, without the need for operator intervention.

3.2.15. Inverter. Device that changes a direct current power source into an alternating current or voltage source.

3.2.16. Legacy equipment. In this standard, refers to any and all military generation, distribution, storage, and load equipment deployed before the release of this standard.

3.2.17. Load. A user device that is powered by the TMG.

3.2.18. Load shedding. Distribution disconnects one or more loads when the generators are overloaded until the overloaded condition is removed.

3.2.19. Operator. A warfighter tasked to run, and maintain the tactical microgrid.

3.2.20. Power Device. A standalone component that is part of the TMG system, including generating sources, distribution, storage, and loads. A power device does not include the TMC.

3.2.21. Open standard. Standards made available to the general public that are developed (or approved) and maintained via a collaborative and consensus driven process.

3.2.22. Performance. The capability of a device when observed under particular conditions.

3.2.23. Point of Connection (POC). The power connection between any power device and the

TMG.

3.2.24. Ring-bus off-line. A ring-bus microgrid configuration where one bus segment is connected but unpowered and kept as a spare. In the event a bus segment is cut, the spare bus segment would be energized.

3.2.25. Setting. Modifies either the software or hardware behavior of the device.

3.2.26. Source (SRC). A device that provides energy to the microgrid, including both generating and renewable sources.

3.2.27. Storage device. A system that saves and stores energy to be used at a later time.

3.2.28. Tactical. A type of generator sets, IAW MIL-STD-1332, designed for high mobility in direct support of military forces where output of generator sets is normally, but not exclusively, used at generated voltages without the necessity of transformation or extensive distribution systems. Life Characteristics are considered secondary to lightweight, small size, and a high degree of mobility. In the context of this document, Tactical applies to all types of tactical microgrid equipment specified in Table 1-1 Types of Equipment in a Tactical Microgrid.

3.2.29. Tactical Microgrid (TMG). A tactical microgrid is a warfighter-operated and maintained power system consisting of a mobile, flexible group of interconnected power generation sources, distribution, storage, and load devices that act as a single, controllable system to provide electricity on the battlefield. Intended to be self-contained and readily deployable, the TMG may utilize alternative energy resources, energy storage, and be capable of interfacing with other grids.

3.2.30. Tactical Microgrid Controller (TMC). A device, which an operator can access to set up, run, or maintain the system, which can communicate with other devices and automatically change their settings.

3.2.31. User. A warfighter allowed to view the current state and make minor changes to the tactical microgrid.

3.2.32. Warfighter. Military personnel with primary skills in combat that may have limited staff with generator experience. Warfighters can be both users and operators.

4. GENERAL REQUIREMENTS

4.1.General. The Tactical Microgrid (TMG) is the essential tool needed to reduce fuel consumption while producing and distributing mission critical electricity on the battlefield. The TMG must have the ability to produce and distribute electricity in a tactical environment effectively, and efficiently to enable the Warfighter to meet mission needs. This section provides general requirements for tactical microgrid interface and design to meet this need.

4.2.Types of Tactical Microgrid Equipment. There are basic components necessary for a tactical microgrid. Each component or end item has specific functions to enable the microgrid to function. These components are classified in para 1.4 and Table 1-1. The basic functions and requirements are summarized in the following paragraphs.

4.2.1. Type I – Power Generation Sources. Type I - Power Generation Sources are end items designed to produce electricity for the TMG. Each item has the capability to operate as an individual power source or can be synchronized to provide power as a TMG. As an individual power source, they can be used to provide power to a single load such as a shelter or radar system. As an element of the TMG, multiple power sources can be synchronized and controlled to turn on and off based on the load on the TMG. Type I equipment includes, but is not limited to, typical diesel engine driven generator sets, alternative energy power sources such as solar, wind, fuel cells, etc. and hybrids.

4.2.2. Type II – Energy Storage Systems. Type II – Energy Storage Systems provide stability to the TMG during transitions and peak shaving. Energy storage systems shall provide power during the period when additional power is necessary but the power source has not been added to the grid. In addition, energy storage systems shall function as an uninterruptable power supply (UPS) or as a hybrid when paired with a power source for individual loads. Energy storage systems shall include energy conversion to enable individual operation or connection to the TMG. Individual operation means not functioning as part of the TMG but can function when connected to a load.

4.2.3. Type III – Feeder Systems. Type III – Feeder Systems are a type of distribution equipment which provide the interface or connection points to the TMG for the other types TMG equipment. Feeder systems define the TMG grid itself. They can be added or subtracted to define the electrical bus necessary to provide the power to the loads directly or through the distribution systems. They can also provide energy conversion of power sources into the TMG or loads out of the TMG. Feeder systems shall include the ability to manage the circuits through independent control or through the use of Type V – Control Systems equipment. Feeder systems shall have metering and monitoring systems incorporated to enable the Warfighter to manually control the system and to automatically control the system using Type V Control Systems

4.2.4. Type IV – Distribution Systems. Type IV – Distribution Systems provide the power from the TMGs through the Type III – Feeder Systems to loads which require individual circuits for standard lighting and standard duplex receptacles. Type II equipment can be individual items or integrated into various shelters. Distribution systems shall include the ability to manage the circuits through independent control or through the use of Type V – Control Systems equipment.

Distribution systems shall have metering and monitoring systems incorporated to enable the Warfighter to manually control the system and to automatically control the system using the Type V Control Systems.

4.2.5. Type V – Control Systems. Type V – Control Systems provide power management for the TMG. Control systems monitor various parameters of the TMG, such as current, and add or subtract power generation sources and/or add or subtract load to ensure power is available.

Control systems shall monitor and protect the system in the event of overload or faults. Control systems shall reside as an individual item or be built into the various types of TMG equipment.

4.2.6. Type VI – Loads. Type VI – Loads consume the power provided by the TMG. Standard loads consume power but do not communicate with the TMG. Smart loads also consume power but can communicate with the TMG to protect the TMG. Smart loads allow the TMG controller to control their loads to prevent the grid from being overloaded. In addition, smart loads can notify the TMG controller about their pending activation. This notification will allow the TMG controller to ensure adequate power is available on the TMG for the additional load.

4.2.7. Type VII – Power Conversion. Type VII – Power Conversion systems enable Type I Power sources and Type II Energy Storage systems which produce different voltages and/or are Direct Current (DC), to connect to the TMG feeder bus. These systems convert the source/storage power to the common TMG bus AC voltage. These systems can be separate items or can be integrated into the source/storage systems they support.

4.3.Interoperability. Individual equipment types specified above, shall communicate, and interact with one another in order to interoperate as a TMG, regardless of manufacturer or version, and without the need for operator intervention. Interactions include but are not limited to starting and shutdown, synchronization, grid connection/disconnection, parallel operation to include proper load sharing, load management, etc. Each item shall have standard power and communication connections to enable this interoperability.

4.4.Standalone Use.

4.4.1. Type I Power Generation Sources and Type II Energy Storage Equipment. Type I Power Generation Sources and Type II Energy Storage equipment shall be capable of operating independently to provide power in a standalone or spot generation configuration. Power generation sources and energy storage systems will be operated independent of the TMG for loads not on the TMG.

4.4.2. Type III Feeder and Type IV Distribution Systems Equipment. Type III Feeder and IV Distribution Systems equipment shall be capable of operation in an independent mode when they are independent of a TMG. Feeder and Distribution systems will be operated independent of the TMG if separated by a fault in the TMG or when providing power distribution for a standalone power source. In addition, Type III and Type IV equipment shall be capable or operating in a manual mode if automatic control is lost.

4.5.Degraded Operation. The TMG shall have the ability to degrade operations when experiencing grid instability, faults, or failures. The TMG shall be capable of autonomous and operator-implemented degraded operation during loss of communication events, equipment failures, and emergency conditions. These capabilities include selective isolation of equipment and segmentation of the grid into two or more smaller microgrids. The minimum degradation will be to disable the TMG controls and operate components in spot generation configurations.

4.6.Monitoring and Control. All types of TMG equipment shall provide status, configuration data, and control for individual equipment and the overall TMG to system operators. Access to this data and information shall be provided through human machine interfaces on the individual equipment and remote interfaces such as the Energy Informed Operations (EIO) dashboard or a standard notebook computer.

4.7.Cybersecurity. Cybersecurity is essential to the operation of the TMG. Although the ability to apply firmware/software upgrades is necessary, individual equipment shall be protected from the introduction of malicious firmware/software into the systems directly or through remote interfaces.

All types of TMG equipment shall conform to DOD Cybersecurity policy as specified in DODI

8500.01. Specific policy areas include: Risk Management, Operational Resilience, Integration and Interoperability, Cyberspace Defense, Performance, Identity Assurance, and Information Technology.

4.7.1. Risk Management Framework (RMF). Individual types of TMG equipment as well as the overall TMG, shall comply with DOD Risk Management Framework policy defined in DODI

8510.01. The RMF shall be based on the National Institute of Standards and Technology (NIST), RMF including Special Publication (SP) 800-39 Managing Information Security Risk:

Organization, Mission, and Information System View, SP 800-53 Rev. 5 Security and Privacy Controls for Information Systems and Organizations, and SP 800-82 Rev. 2 Guide to Industrial Control Systems (ICS) Security. The RMF applies across the System Development Lifecycle (SDLC) of the individual items and how they communicate within the TMG. Applying standards-based cybersecurity as early as possible in the SDLC can also help improve its effectiveness at a reduced cost compared to waiting until later phases in the lifecycle.

4.7.2. Operational Resilience. Individual types of TMG equipment as well as the overall TMG, shall ensure information, data, and services are available to other elements of the TMG.

Technology components (e.g., hardware and software) shall have the ability to reconfigure, optimize, and recover with defense in depth. Attempts made to reconfigure, and recover shall be logged in an audit file.

4.7.3. Access to firmware/software. Access control methods and procedures shall be implemented to mitigate cyber threats to individual equipment. Strong identities, assured access, trustworthy logging, and integrity-protected operations form the core list identified and defined within this document:

Strong identities help maintain a trustworthy sense of what people, processes, and devices are taking action within the system.

Assured access helps guarantee that authorized identities have appropriate access to system resources in order to, for example, initiate commands or collect telemetry.

Trustworthy logging allows TMG Operators to operate and troubleshoot a running system and cyber analysts to perform forensic analysis after a cyber-event has been detected.

Integrity-protected operations ensure the trustworthiness of data and operations within the system and help assure that accidental and malicious changes to the system are detectable.

4.8.Tactical Microgrid Architecture. The components of the Tactical Microgrid are required to interface with one another through a common power bus and microgrid control system communications bus. The basic architecture is shown in Figure 1 Tactical Microgrid Schematic.

All types of TMG equipment shall conform to the following architecture requirements.

4.8.1. Common Microgrid Control System. Type V Control Systems shall interface with other types of TMG equipment to provide automatic microgrid control of those devices. The control communications shall be accomplished over an OSI Layer 1 medium that is capable of Ethernet transmission. Standard connectors and cabling shall withstand environmental characteristics specified herein. The communication bus shall be capable of being disconnected without interrupting the operation of the TMG.

4.8.2. Common Microgrid Monitoring System. All types of TMG equipment shall have the capability to provide operational data to a central monitoring system using an OSI Layer 1 medium that is capable of Ethernet transmission. Standard connectors and cabling shall withstand environmental characteristics specified herein. The communication bus shall be capable of being disconnected without interrupting the operation of the TMG.

4.8.3. Levels of Control. The Tactical Microgrid equipment shall have internal controls and be capable of accepting TMG control from outside sources. The internal equipment controls enable the individual equipment to perform their functions independent from a TMG. The TMG control enables the primary functions of the TMG to be accomplished while connected to the individual components. In order to prevent control issues, the TMG level of control shall not override the

Figure 1 - Tactical Microgrid Schematic internal control functions of the equipment. TMG level control shall activate/deactivate local equipment controls to meet TMG functionality.

4.8.4. Tactical Microgrid Control (TMC) Redundancy. Electricity is mission critical in many TMG applications. The TMG must provide continuous, reliable and stable electricity to the user.

Type V Control Systems equipment provide the TMC. To ensure TMG reliability and stability, there is a need to have redundant TMCs. Redundancy is accomplished by incorporating Master and Standby modes into the TMC. This redundancy enables a second TMCs, operating in standby mode, to maintain TMG function when the TMC in the master mode fails. The relationship between TMCs is:

• All TMCs receive data from all devices.

• Only the TMC in the master mode can send commands or setting changes.

• Devices reject commands from other TMCs.

• Failure of the TMC in the master mode shall trigger the automatic selection of a different TMC to operate in the master mode. TMCs in standby mode shall monitor the TMC in the master mode commands and setting changes in order to maintain a stable grid when they become active. The TMCs in standby mode will automatically take control using these commands and settings until new commands and settings become necessary based on operational data.

4.8.4.1. Protection coordination. All microgrid devices have some level of automated, threshold-based fault protection. Protection coordination sequences contactors and engages loads/sources for power system black-start, circuit partitioning, and circuit re-closing. Protection coordination also monitors power flows to prevent an over-current condition on a Type III feeder or Type IV distribution bus.

4.8.5. Communications Architecture. All devices operating on the Tactical Microgrid shall operate on a common Ethernet communications network. The selected communication protocols are shown in Table 4.1.

Table 4-1: Tactical Microgrid Communications Stack (TMCS)

Layer TMS Implementation

Applications Microgrid Control

Data Objects TMCS Data Objects

Middleware Data Distribution Service (DDS)

Transport User Datagram Protocol (UDP)

Network Internet Protocol Version 6 (IPv6)

Physical Ethernet (802.3)

4.9.Data Model. The data model is defined in terms of data flows and data types. Data flows define the motion of messages while data types define the contents of messages, as some tactical microgrid functions require coordination between devices.

The TMS data model includes all messages sent among TMS devices. These messages are used to communicate all system health, status, command, and control information. They are also recommended for communications with external networks.

The data model provides a common language used by all TMS devices. It is platform independent to allow flexibility in device design and implementation. It contains detailed data flow and data type definitions to guarantee interoperability between devices, regardless of make or mode.

The data model allows for design and implementation flexibility while still taking into account such considerations as security, performance, simplicity, interoperability, and extensibility.

Tactical microgrid devices shall use this data model to implement all functions defined in this standard. Having a common data model is essential for interoperability between devices.

Tactical microgrid devices may additionally use other communications to implement functions not defined in this standard. If such additional communications add functionality that is within the scope of this standard, then they should be proposed for inclusion in future revisions of this standard.

The roles and responsibilities for the TMG elements are defined in Section 5.3, with technical requirements defined in the appendix.

4.9.1. Device Identity. In the TMS data model, every device shall have a unique identity, assigned by an Identity, which is bound to a single, specific device role that has a number of built-in requirements and permissions. This approach simplifies the communications by preventing any ambiguity about how roles may interact. Under all circumstances, every TMS device role shall have its own unique Fingerprint. Since there will likely be multiple devices assigned to the same role, such as generators, the Fingerprint data type assigns a unique identity to each device, regardless of the device role. Data Types, such as Fingerprint, are discussed in Appendix Chapter A and Appendix Chapter B.

4.9.2. Device Roles. Device roles are defined building blocks within the TMS that provide modularized functionality. Each role is assigned based upon the device’s capabilities in the TMS.

Each device role is pre-defined in both functionality and power/communication interfaces to provide modular flexibility. Pre-defined components and interfaces allow customizable modularity in each TMS system to meet the unique needs of each microgrid installation. By using the device roles to define specific functionalities in the microgrid, any number of devices, regardless of capacity size, can be procured and assembled into a single TMS that meets the mission needs. There are two types of device roles in TMS: Control Services and Power Devices.

Figure 2 below, shows the relationship between these roles.

Figure 2 TMS Device Roles

4.9.3. Platforms. A platform is a group of TMS devices assembled into a larger physical package. Platforms may integrate multiple device roles. Each device on a platform shall have a separate identity and role. Multi-role products shall have separate identities and device roles for each type of functionality. Multi-role products shall communicate as if they were multiple physically-separate devices. It is recommended that each device role have its own data connection and run on a separate processor so each role can be physically isolated. If multiple devices are packaged into a single platform or multi-role product, they may share hardware or software components. If such sharing does occur, then all messages shall be sent separately for each contained device identity and role. Messages may be received singly and re-shared using internal mechanisms.

4.9.4. Data flows. TMS devices shall communicate through pre-defined data flows to share all operating information such as power commands and status. For simplicity, the device roles may be shown in the data flows throughout this document with abbreviated names - either P* for the Power Device role or C* for the Control Service device role - to represent any device in that category. Every data flow contains one or more topics. Each topic is defined with a name, publishers that send data, subscribers that receive data, a data type that specifies what values can be transferred, and timing that specifies when data is transferred. Data flows shall be defined using a publisher/subscriber (pub/sub) paradigm that defines the data flows in terms of logical connections. The underlying software and hardware may use buffers, filters, and a mix of broadcast, multicast, and point-to-point connections to implement the flow. These details are specified by the OMG DDS standard as used by TMS. A data flow containing a single topic is provided in Figure 3.

Each topic has the following key features:

Publisher is the Device Role(s) that sends these messages.

Subscriber is the Device Role(s) that receives these messages.

Topic is the name/identifier for these messages and the message flow.

Timing is the condition that causes messages to be sent and the reliability of the message flow.

4.9.5. Publishers and Subscribers. Device Roles shall be used to specify the source of the message, which is the publisher, and the receiver of the message, which is the subscriber, for each data flow. While a device role can be both a publisher and subscriber, typically in an individual flow it is one or the other. Conceptually, all publishers send all messages to all subscribers on a topic.

4.9.6. Topic and Message Flow. Topics shall be used to identify the data flows. Topics define a small group of TMS data flow message topics that have closely related values and match the publishers to the subscribers for each message chain. Multiple data flow topics are used together in larger patterns to achieve system-level TMS behaviors. Each data flow topic shall have a single unique data type with defined event trigger and reliability metrics, which are discussed below. The same data type shall be used by multiple data flow topics, providing a common connection between similar data flows.

The arrows in the data flow diagram indicate the flow of the message stream for the messages sent and received. The arrowhead indicates the direction that messages are being sent. The message stream for the data flows is published following specific data flow patterns that are pre-defined in the TMS. Arrows indicate messages that can be sent from both the initiating publisher and the subscriber in response to the publisher. Data flow patterns, including the subscriber response patterns, are discussed in further detail below.

4.9.7. Data Types. Devices shall use the TMS-defined data type that is assigned to each topic.

The type identifies possible values for the messages where each message may have a different value. Platform-independent logical types are defined in Appendix Chapter B, Detailed Data Model Requirements. Platform-specific details such as data APIs and network serialization are defined in Appendix Chapter D, DDS Requirements.

Figure 3 - Data Flow Notation

Timing

Publisher Subscriber

Topic

ExampleTopic Periodic 1 s P* C*

4.9.8. Data Flow Patterns. The data flows identify and describe the system-level behaviors of TMS communication between devices through a set of pre-defined messages. There are three basic patterns of data flows that messages between devices follow: Status, Request/Response, and Custom.

4.9.8.1. Status data flow pattern. The status data flow messages shall provide status of the device that publishes the message. Figure 4 provides an example of a status data flow pattern. These messages do not require a reply or response from any subscribing devices.

The timing of these messages shall occur when an event triggers the message to be sent.

Examples of event triggers include when a device starts up or if an error condition occurs.

4.9.8.2. Request/Response data flow pattern. Request/Response messages shall require interaction between devices in the form of command and acknowledgment. Figure 5 provides an example of a request/response data flow pattern, where MC is the Microgrid Controller, P* is the Power Device role, and. MD is the Microgrid Dashboard.

A command is a request having immediate effect. Other requests may be deferred for later execution. A reply is a data sample update sent in response to a request.

4.9.8.3. Other responses include actions taken to complete a request. A Request is sent from one device to another, which responds to the request. Related status may be sent to a third device. An example of this data flow pattern is a health status request sent to a TMS device from the user interface to which the device responds and also sends additional related status.

Custom data flow pattern. Custom messages shall have a unique interaction pattern that doesn’t match the Status or Request/Response patterns. Each custom data flow pattern shall have

Figure 4 - Sample Status Data Flow Pattern

Status

ExampleTopic Periodic 1 s P* C*

Request Related Status

ExampleRequest As needed

RequestResponse ExampleStatus On change

Response

P* MD MC

Figure 5 - Sample Request/Response Data Flow Pattern message interactions that are unique and specific to that one condition. Typically custom patterns define a TMS system-level behavior.

4.9.9. Instances. Some data flows have a single value that applies to the entire microgrid. Other data flows have different values for each device in the microgrid or even for each power connector in a single device. These different values are called sample instances. Editorial note:

Working on a summary of the various key values and where they are used. This is being revised in the tech refresh.

4.9.10. Timing Effective communication requires a careful balance between sending messages frequently, so important information is not delayed, and limiting the frequency and size of messages, so resources are not overloaded. Each topic shall have timing requirements that define when new messages are sent, how frequently new messages can be sent, and when old messages are re-sent. These timing requirements shall be used to define behaviors and to derive minimum resource allocations for software and hardware in TMS devices. Topic data values change over time. Each new value is called a sample. When a publisher updates a sample, one or more messages will be sent to transmit the new value.

There is not a direct, one-to-one mapping between sample updates and messages. For example, the communications software may bundle multiple samples into a single message, split a single sample across multiple messages, or re-transmit samples when messages are lost. Any such mapping is compliant as long as the overall timing requirements are met. The OMG DDS middleware allows the re-use of timing standards and software implementation.

Timing requirements apply to the business logic in a TMS application, the OMG DDS middleware software library, operating system, and network hardware. There shall be four major timing requirements: data trigger, rate class, burst size, and quality of service (QoS).

The first three requirements shall be defined in terms of sample updates. The QoS defines how these translate into messages. See Appendix Chapter A.8.5.

4.9.10.1. Event trigger. An event trigger is a pre-defined condition that causes sample updates. Fixed rate samples shall be triggered by a periodic timer set to a nominal rate.

Variable rate samples shall be triggered by a given type of event. Details such as the event trigger for each topic type, rate limits, and timing parameters are defined in Appendix Chapter A, Data Model.

4.9.10.2. Rate limit The rate limit shall provide minimum separation time interval between sample updates. Upper bound on the rate of transmission and hence resource utilization. The publisher shall not send messages until after this minimum separation time interval. The network or subscriber may drop messages sent at a higher rate

4.9.10.4. Deadline. Deadline is the maximum separation time interval between sample updates. Lower bound on the rate of transmission and hence resource utilization. The publisher shall send updates before this maximum separation time interval. The subscriber may trigger an error-handling behavior if updates are not received on time.

4.9.10.5. Quality of Service (QoS). Quality of service is the policy defining how data samples are prioritized, buffered, sent, and re-sent as messages. Accounts for constraints in network connectivity. A fully specified policy is called a profile. The QoS profile may include information from the rate limit and deadline.

Figure 7 Example Timing for a Periodic 1s topic

5. DETAILED REQUIREMENTS

5.1.Safety The TMG interfaces required in this standard shall not cause harm to the Warfighter or damage equipment. Equipment developed in accordance with this standard shall comply with Army Regulation 385-10, The Army Safety Program. As a minimum, all interfaces shall meet various safety requirements as specified in MIL-STD-882 System Safety; NFPA-70 National Electric Code and NFPA-70E Standard for Electrical Safety in the Workplace.

5.2.Human Engineering The human interfaces required to implement the requirements specified herein, shall meet the design criteria requirements of MIL-STD-1472 Human Engineering.

5.3.TMG Equipment Roles and Responsibilities Each type of TMG equipment has specific roles and responsibilities when connected to the TMG. The roles and responsibilities define the functions of the item. There are related data flows in DDS which enable the functions to be performed. Detailed Data flows used to enable the equipment to meet their roles and responsibilities are defined in Appendix Chapter B. The roles and responsibilities for each type of TMG equipment are as follows:

5.3.1. Type I – Power Sources The role of the power source is to provide power to the grid.

Power sources are responsible for producing quality electricity for the TM. Power sources shall, accept commands from and provide operational parameters to Type V Control Systems in order to optimize microgrid operation. The power source shall provide power in accordance with its individual specification and shall be capable of accepting and implementing commands from Type V equipment either internal or external to the item.

5.3.1.1. Standard Power Source Functions The following standard power source functions and related commands shall be used to enable the power source role to be met:

Table 5-1: Type I Standard Power Source Functions Function Reporting Data Flows

a. Discovery Publish/Subscribe B.5 Device Announcement B.20 Power Topology B.4 Heartbeats

b. Start Publish/Subscribe B.18 Remote Start/Stop

Table 5-1: Type I Standard Power Source Functions Function Reporting Data Flows c.

Feeder System

Contactor Control

Publish/Subscribe Special signal, see text.

d. Parallel Operation Publish/Subscribe

B.18 Remote Start/Stop B.23 AC Load Sharing B.24 DC Load Sharing B.16 Tuning Parameters e.

Monitor

Operational Parameters

Publish/Subscribe

B.8 Control Hardware Status B.9 Power Hardware Status B.12 Diagnostics Reporting B.20 AC Measurements B.21 DC Measurements

f. Drop Load Publish/Subscribe B.23 AC Load Sharing B.24 DC Load Sharing

g. Shutdown Publish/Subscribe B.18 Remote Start/Stop

a. Discovery. The discovery function enables the device to be recognized as a member of the TMG. This function initiates communication from the device to other members and determines acceptance and identification.

b. Start. The start function enables the TMG controller to direct the power source device to prepare to provide power to the TMG bus. The start function initiates the operation of a power source prior to connection to the TMG. This function varies with the type of power source. For example, with a standard engine driven generator set, this function turns starts the engine and ensures frequency and voltage are produced.

Whereas, with a wind turbine, this function enables the wind turbine to turn and ensures frequency and voltage are produced.

c. Feeder System Contactor Control. This function is a safety mechanism used to prevent power from being fed back to the load terminals of a non-operating power source. It enables the power source to send activation/deactivation direction to Type III Feeder System contactor to connect the power system to the TMG bus. This is a special signal, with a dedicated direct connection between devices, and thus not part of the data model.

d. Parallel Operation. The parallel operation function enables the TMG controller to direct the power source to connect power to the TMG bus. The parallel operation function synchronizes the power source to the TMG, safely connects it to the TMG, and enables proper load sharing between power sources and the TMG.

e. Monitor Operational Parameters. The monitor operational parameters function enables the TMG controller to monitor the operation of the power source.