SDC-5617 DC Battery Monitoring System R0 dls.pdf

DC Battery Monitoring System

ISSUING DIVISION: Operations & Maintenance Engineering Signed by ____________________ SVP SPONSOR: Hark Choong, Sr. Utility Engineer-Substation Date Signed ____________________

Revision 0 Sheet 1 of 11

SECTION: Substation – DC Systems SDC 5617

Scope of Standard Purpose of Revision References Rescissions Definition of Terms Background Objective Battery Monitoring System: SVP Requirements Battery Monitoring System Installation Guidelines and SVP Setpoints NERC PRC-005-6 Compliance Requirements NERC TPL-001-5 Compliance Requirements Site Acceptance Testing SVP Approved Battery Monitoring Systems

Table 1: SVP Alarm Setpoints for BMS Table 2: NERC PRC-005-6 Table 1-4(f)

Figure 1: Battery Terminal Connection Resistance Figure 2: Battery terminal voltage during discharge cycle Figure 3: Typical Sense Lead Tab Washer Installation example Figure 4: Typical Hardware Stacking example Figure 5: Typical clamp sense lead connection example

01/24/2025

By: Hark Choong DC Battery Monitoring System

Silicon Valley Power

Drawn By: HSC Approved: 01/24/2025 SHEET 2 of 11 Sanjeev Gupta

SD-5617

Rev.

Scope of Standard

This Document is a guide for design, installation, programming, testing and compliance reporting of Battery Monitoring System on DC Battery Banks in SVP facilities. It is a part of a set of substation DC Systems design and construction documents for Electric Utility Engineers, Design Consultants, Equipment Manufacturers, Construction Contractors, and Field Construction and Maintenance personnel.

Purpose of Revision

This is a new document in the Substation DC Systems section of the Substation Design and Construction Manual. There is no revision at this time.

References o IEEE P1491 – Recommended Practice for Battery Monitoring in Stationary Applications o IEEE 450 – IEEE Recommended Practice for Maintenance, Testing and Replacement of Vented

Lead-Acid Batteries for Stationary Applications o IEEE 1106 – IEEE Recommended Practice for Installation, Maintenance, Testing, and

Replacement of Vented Nickel-Cadmium Batteries for Stationary Applications o IEEE 1188 - IEEE Recommended Practice for Maintenance, Testing, and Replacement of Valve-

Regulated Lead-Acid (VRLA) Batteries for Stationary Applications o NERC Standard PRC-005-6 – Protection System, Automatic Reclosing, and Sudden Pressure

Relaying Maintenance o NERC Standard TPL-001-5 – Transmission System Planning Performance Requirements

Rescissions

This is an original document that has not been previously issued by the SVP Electric Engineering Division. No documents are superseded by this document.

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Definition of Terms o City: City of Santa Clara or the City Council of the City of Santa Clara.

o BMS: Battery Monitoring System, which is a permanently installed system for measuring, storing, and reporting battery operating parameters.

o BES: Bulk Electric System.

o High Voltage: SVP Electric facilities operating at 60,000 Volts or above.

o Float Voltage: It is the voltage at which a battery is maintained after being fully charged to maintain that capacity by compensating for self-discharge of the battery.

o Internal Ohmic Measurement: Measurement of electronic and ionic conduction path within a cell or unit, using commonly used units of measurement such as impedance, conductance or resistance.

o Contractor: The person or persons, firm, partnership, corporation or combination thereof, who has entered into a contract with the City of Santa Clara, as a party or parties of the second part of his or their legal representative.

o Program Engineer: Subject Matter Expert (Sr. Engineer) for Silicon Valley Power.

o Silicon Valley Power (SVP): Municipal Electric Department of the City of Santa Clara.

o NERC: North American Electric Reliability Corporation is international regulatory authority for

North America, subject to oversight by the Federal Energy Regulatory Commission (FERC) and governmental authorities in Canada.

Background

DC Battery Bank is an integral part of a Substation or a Generation Facility, with all protection relays and schemes depending on it for proper functioning. It supplies the ‘energy’ required to operate the protective relays and high voltage interrupting devices to safely isolate the electrical faults on our Electric System.

During normal operation, DC Battery Charger (or chargers) maintains a float voltage on the DC system (including DC Batteries) and provides continuous load current to all the connected loads. During an outage when AC service to the DC Battery Charger is interrupted, DC batteries act as backup source and provide load current to all connected DC loads. A normal DC Battery bank is sized to continuously supply the connected load for 8 hours.

To ensure that this DC power system in a Substation or Generation Facility can perform as expected, it is important to continuously monitor and record the health of Battery System components. This continuous monitoring system can help with a comprehensive understanding of the Battery component’s operating condition and provide mechanism for intelligent analysis of overall Battery System health and performance.

This ensures continuous reliability and supplement SVP’s monthly battery inspections.

Benefits of a Battery Monitoring System include:

1) Automation of various Battery measurements and readings, that would otherwise have to be performed manually.

2) Greater frequency and consistent accuracy for on-line measurements on battery system.

3) Alarm notifications in real time for out-of-tolerance readings.

4) Continuously monitor various parameters of a Battery System, even during a discharge event.

Thereafter, store and analyze the same data to generate operational or compliance reports.

Limitations of a Battery Monitoring System are:

1) A monitoring system cannot perform a visual inspection of the batteries for sulphation, mossing or seal leaks.

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2) Visual inspection of the rack.

3) Inspection of eye wash station.

4) Battery System regular maintenance tasks, such as topping off Electrolyte.

5) Battery Monitoring System Alarms need to be tested every 12 years for PRC-005-6 Table 2 compliance

Objective

Three primary objectives of installing a Battery Monitoring System are:

1) NERC PRC-005-6 Compliance for station DC supply (battery system) per table 1-4(a) – (e) by having monitoring attributes as outlined in table 1-4(f) of the standard.

2) Comply with NERC TPL-001-5 Table 1 footnote 13 that requires either redundant battery systems or continuously monitored single battery system that is reporting alarm to SVP Control Center for low voltage and open circuit.

3) Reduced station maintenance costs and SVP resource demands.

Battery Monitoring System will need to be installed at:

1) New substation and rebuild projects by SVP CIP team

2) All planned or emergency battery replacements by SVP Operations

Despite the continuous monitoring of the DC battery systems, some inspection tasks will still need to be completed by SVP Substation Techs or Generation Techs. These are outlined below:

1) Overall cell condition for all individual cells in a battery system

2) Electrolyte level check, and refill if necessary

3) Visual inspection of the battery rack and eye wash station

4) Battery Monitoring System Alarm verification every 12 years for PRC-005-6 Table 2 compliance

5) Battery Monitoring System alarms to SCADA must initiate a response and investigation within 24 hours

6) Substation Maintenance Procedure must include regular preventative maintenance on BMS, as specified by the manufacturer

NOTE for SVP Operations: All Battery Monitoring System alarms will need to be addressed similar to other Substation or Generating Facility critical alarms, i.e. within 24 hours.

Battery Monitoring System: SVP Requirements

SVP design requirements are driven by IEEE standards, NERC PRC-005-6 standard and NERC TPL-001- 5 standard.

The following parameters shall be monitored and measured, either continuously or at set intervals (not to exceed 24-hour max interval between measurements) by the Battery Monitoring System:

1) Voltage: Individual cell voltage, battery terminal voltage. Optional: partial string voltage, battery mid-point voltage, positive-to-ground voltage (if DC ground detection alarm available separately) and negative-to-ground voltage (if DC ground detection alarm available separately).

2) Current: Float, recharge and discharge current by mounting a current sensor on positive cable on

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Cell-1 or negative cable on Cell-60. Current sensor must have DC String Float Current measurement accuracy of 5%.

3) Temperature: Individual cell temperature and ambient temperature recorded in degrees Celsius or Fahrenheit.

4) Intercell connection resistance: All intercell strap connections are measured and recorded in micro-ohms.

5) Battery terminal connection resistance checks: Resistance measure for two external cable terminations, for cables coming from the DC battery charger to the DC batteries.

a. DC cable Lug to Cell-1 positive terminal

b. DC cable Lug to Cell-60 negative terminal

Figure 1: Battery Terminal Connection Resistance

6) Internal Ohmic Measurement checks: Each cell /battery is measured for internal impedance or ohmic values, which can be compared to a baseline. Baseline values must be taken from the BMS after it is fully installed. Previous baseline values from battery commissioning tests cannot be used for baseline on a Battery Monitoring System. Confirm with BMS manufacturer if battery vendor specified internal cell impedance/ohmic values can be used or not.

7) Optional: Electrolyte level in each cell.

The following analysis and reporting capabilities are required by the Battery Monitoring System:

1) User settable time setting for BMS to measure and record parameters noted in the section above. If user cannot define measurement intervals, then at least once-a-day measurement of parameters noted in the section above.

2) Optional: Discharge run-time recording of battery parameters, along with run-time prediction during discharge. Run-time prediction during discharge and battery charge/discharge cycle count are preferred, but not necessary.

3) Alarms: Battery Monitoring System must be able to record and analyze data to generate the following alarms, which can be mapped to its dry output contacts for SCADA alarming.

a. High voltage and low voltage alarms for string voltage at battery terminals.

b. Optional: Alarming for low electrolyte and low specific gravity for each individual cell in battery string.

c. Ground Fault detection and alarm: Monitor continuously for any unintentional grounds on

DC system and provide alarm if present.

d. Float voltage monitoring and alarming to ensure correct voltage is applied to the string, by measuring voltage at battery terminals where charger cables terminate.

e. Battery string continuity: BMS must monitor DC string float current at the positive and negative cable terminations, and provide alarm if the battery has a continuity fault.

Alternatively, BMS can measure potential difference across the cell interconnections as well to detect open string or continuity fault.

f. Optional: DC Battery Charger to Battery Terminals continuity and resistance

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g. Intercell and Terminal Connection Resistance: Monitor and alarm for each individual cell-to-cell resistance and lug-to-post terminal connection resistance (on positive & negative cable terminations).

h. Internal Ohmic value: Monitor and alarm for each cell’s internal impedance or ohmic value against an established baseline.

i. Individual Cell Voltage monitoring, with alarm asserted at ±15% deviation from baseline cell voltage.

4) Measure and record Battery terminal voltage continuously, to trend and analyze initial voltage dip and recovery during the start of a discharge cycle of fully charge battery bank. Refer to Figure 2 below.

5) Data Recording, Analysis and Reporting: Generate reports for NERC PRC-005-6 compliance, on quarterly, bi-annual or annual basis. Data recording and availability of trending to help SVP Engineers with battery state of health analysis for condition-based maintenance and replacement before failure.

Figure 2: Battery terminal voltage during discharge cycle

Other features of Battery Monitoring System:

1) Battery monitoring system must be rated for VLA and VRLA batteries (SVP utilizes both types throughout the system).

2) Communication Interfaces for connection to SVP RTU, via DNP3 (SVP preferred) or MODBUS protocols. Manufacturer to provide DNP3 and MODBUS point mapping spreadsheet to SVP.

Battery monitoring system must have at least one Ethernet port for this connection to RTU.

3) Indoor application, for temperatures ranging from 0 degrees Celsius to 50 degrees Celsius.

4) Single Power Supply for the processing module, 120VAC or 125VDC (120VAC or 48VDC for

48VDC Battery Banks).

5) Conformally coated and rated to be installed in a battery room environment.

6) Equipment grounding in accordance with NFPA 70, NEC or other applicable codes.

7) All BMS components that connect directly or indirectly to the battery must be rated for full battery voltage (600V maximum).

8) All BMS sense leads to be equipped with in-line current limiting device that is rated up to the maximum overall string voltage and can clear short-circuit up to the maximum available short-circuit amperage rating of the battery.

9) For Vented Lead Acid batteries, sense leads installed on the terminal connector must be acid-resistant.

10) Date and time stamp each measurement or event.

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11) User modifiable settings, that include but are not limited to, measurement/recording intervals, user-defined preset thresholds for alarms and automatic action (dry output contact closing) to notify SVP

SCADA.

12) SVP prefers Battery Monitoring System alarm output contacts to be rated for 125VDC. SVP will accept BMS with alarm output contacts rated below 125VDC as well, with prior notice from the manufacturer and approval by SVP SME.

13) SVP requires at least one Alarm Output contact (Normally Closed) from BMS, where all parameters can be combined to send one general alarm to SCADA. Preference is for two Alarm Output contacts for Major and Minor alarm.

Battery Monitoring System Installation Guidelines and SVP Setpoints

Battery Monitoring System (BMS) shall be installed inside the Battery Room in Control Enclosure of SVP Substation or Generation Facility.

1) Follow all OSHA and IEEE safety guidelines while working with or near a DC battery bank.

2) Install BMS in a NEMA-1 enclosure, mounted on the wall beside the Battery Bank, with easy access for SVP technicians.

a. Installation of BMS and NEMA box above the battery bank is not permitted, as that may require technicians reaching over the batteries with their tools to troubleshoot BMS system.

3) Only qualified electricians are permitted to install a battery monitoring system, under the guidance of a qualified BMS manufacturer representative. Qualified electrician must review all vendor provided documentation on BMS installation, prior to beginning their work.

4) Connection hardware used for BMS installation must be stainless steel or lead-plated copper for lead-acid batteries and nickel-plated for nickel-cadmium batteries.

5) Properly torque all battery terminals after installation of sense lead tab washers per manufacturer specifications. Use of ‘double nut’ installation method is prohibited since it impedes the ability to properly torque the system during future inspections. Refer to Figures 3, 4 and 5 for more information on sense lead tab washers and quick connect sense leads, referenced from IEEE P1491 standard.

6) Install a Panduit along the wall behind the battery rack to run all cables required by Battery Monitoring System. All wires must be installed in an organized manner consistent with best workmanship practices and must not interfere with future inspections and preventative maintenance, including replacement of individual battery cells. All sense leads/wires for BMS must be carefully routed to avoid contact with battery terminals and grounded equipment to minimize the risk of short circuit or ground leakage.

7) Individual cells of multiple-cells mono-block batteries should be individually monitored whenever possible.

8) Baseline values must be taken from the Battery Monitoring System after it is fully installed.

Previous baseline values from battery commissioning tests generally cannot be used for baseline on a new Battery Monitoring System installation.

9) Route a CAT6 cable from BMS to SVP RTU for communications. Consult with SVP Engineer for site specific instructions.

10) Route a 4-conductor copper cable from BMS to station annunciator SEL relay. Consult with SVP Engineer for site specific instructions.

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Figure 3: Typical Sense Lead Tab Washer Installation example

Figure 4: Typical Hardware Stacking example

Figure 5: Typical clamp sense lead connection example

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SVP alarm setpoints for measured values by Battery Monitoring System are shown in Table 1 below.

Table 1: SVP Alarm Setpoints for BMS

Measured parameter by BMS Alarm set points Battery Terminal Voltage (or overall voltage)

High alarm= (Float voltage per battery manufacturer) + 1V Example: for 125VDC VLA battery bank of 60 cells and 2.23V per cell float voltage recommendation by battery manufacturer, setpoint for high voltage alarm should be 135VDC.

Low alarm= for 125VDC bank, setpoint= 125VDC; for 48VDC, setpoint= 48VDC; for 24VDC bank, setpoint= 24VDC.

Individual Cell Voltage High alarm= 2.6V per cell (or +15% of baseline cell voltage) Low alarm= 1.9V per cell (or -15% of baseline cell voltage) Note: setpoints may vary based on type of battery. Refer to battery manufacturer specifications or consult SVP Engineering

Battery Ground Fault For any ground fault currents above 0 Amps, or positive/negative terminal-to-ground voltage deviation of ±20% or more than normal voltage.

Ambient temperature (25 degrees Celsius ideal)

Below 10 degrees Celsius or above 28 degrees Celsius.

DC Battery String Float Current High alarm= 5 A DC Low alarm= 0.1 A DC or below

DC Charger to Battery Terminal Cable Resistance

Alarm on Open detection, or ±20% or +20 μ-ohms (whichever is greater) from Baseline Reading

Individual Cell Ohmic or Impedance value

±40% to the baseline value or manufacturer specified value

Intercell connection resistance ±20% or +20 μ-ohms (whichever is greater) from Baseline Reading

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NERC PRC-005-6 Compliance Requirements

NERC PRC-005-6 Standard for Protection System, Automatic Reclosing and Sudden Pressure Relaying Maintenance provides a framework for bypassing 4-month, 18-month and 6-year maintenance activities as outlined in Table 1-4(a) to 1-4(e). SVP requirements for Battery Monitoring System align with NERC PRC- 005-6 table 1-4(f).

Table 2: NERC PRC-005-6 Table 1-4(f)

NERC TPL-001-5 Compliance Requirements

Footnote 13(c) of TPL-001-5 – Transmission System Planning Performance Requirements states that:

“A single station dc supply associated with protective functions required for Normal Clearing (an exception is a single station dc supply that is both monitored and reported at a Control Center for both low voltage and open circuit)” With Battery Monitoring System installed per this SVP standard, it’ll no longer be required to have two DC battery banks at SVP facilities to meet TPL-001-5 redundancy requirements.

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Site Acceptance Testing

Battery Monitoring System shall be tested and commissioned per manufacturer’s guidelines.

The following are SVP requirements for Site Acceptance Testing:

1) Preferred: Final Site Acceptance testing be performed under BMS manufacturer representative’s supervision.

2) SVP Engineer and/or Technician must be present to witness Site Acceptance Testing.

3) BMS final as-left settings PDF printed and signed off, certifying all parameters are set per SVP standard and all alarm points were tested up to SVP SCADA.

4) Preferred: BMS Manufacturer’s commissioning checklist/certificate completed after Site

Acceptance testing.

5) Baseline values properly set-up in BMS, PDF printed and signed off.

6) Redline Control Enclosure drawings for final installation of BMS and any BMS manufacturer provided drawings to be submitted to SVP

SVP Approved Battery Monitoring Systems

Following are SVP approved Battery Monitoring Systems:

• Eagle Eye Power Solutions VIGILANT battery monitoring system (Under Pilot Program)

• EMSYS Battery Monitoring System CellSPY (Under Pilot Program)

SVP will standardize on a single vendor battery monitoring system after successful completion of Pilot Program.

Pilot Program outline:

1) Install EMSYS CellSPY Battery Monitoring System at NRS, KRS and SRS substations as a part of the rebuild project. Concurrently, install Eagle Eye VIGILANT battery monitoring system at Juliette Substation and Space Park Junction for 60KV system.

2) Evaluate Eagle Eye VIGILANT and EMSYS CellSPY systems after 6-12 months in operation and compare to PBT-SC4 battery monitoring system installed at SSS substation.

3) SVP Operations Engineering to create an evaluation matrix to compare these different products, to standardize on one single system for SVP.

4) SVP Operations Engineering to kickstart another Pilot Program in future if new technologies and new manufacturers start offering Battery Monitoring Systems.