The Objectives
- NERC PRC-005 Compliance
- Data-Driven Cost-saving Optimal Battery Maintenance
There are multiple factors driving utility operators to seek a reliable, validated, and advanced Battery Monitoring System (BMS) for their power plants and substations. The ideal BMS will perform battery tests more accurately and efficiently than human technicians, while being ultra reliable over 20+ year service life for typical vented lead-acid batteries.
1) Demand for Increased Reliability and Performance of Battery Systems
Lead-acid batteries remain the most reliable energy storage option for power plants and substations, and effective battery monitoring can guide proactive maintenance, testing, and replacement to achieve optimal battery service life and reliable operation.
2) Reducing the Cost of NERC Compliance and Maintenance
NERC regulations mandate scheduled inspections and proper maintenance.
Implementing effective monitoring will mitigate the risk of regulatory fines
and reduce costs through efficient performance-based maintenance.
The maximum Penalty amount that NERC or a Regional Entity will assess for a violation of a Reliability Standard Requirement is $1,000,000 per day per violation.
3) Substation Automation for Increased Accuracy and Improved Efficiency
On-site battery measurement and data interpretation requires trained/experienced personnel, which can lead to significant travel and time expenses when dealing with numerous batteries in hundreds of locations. With real-time and accurate data, a battery subject matter expert can remotely supervise effective maintenance activities for hundreds of battery installations.
4) Lessons from Poorly Maintained Batteries
When well-built batteries with 20-year designed life are not properly maintained, they may only last less than half that time. The shortage of experienced technicians can result in delayed identification of battery problems, which can cause operational failures and costly battery replacement.
5) Upgrade Poorly Designed Legacy BMS
Many operators have been disappointed with their installed BMS:
a) Data is not accurate, or not relevant to battery deterioration. Data and alarms were not utilized to guide the proactive maintenance.
b) Older BMS are unreliable, and could not withstand harsh environments found in battery rooms, and therefore BMS maintenance cost of legacy systems has been too high. Many of those BMS systems were discarded or abandoned after a few years.
c) Centralized battery data management from legacy BMS was difficult to implement and not user friendly.
RFP / RFQ Preparation
While many RFP/RFQ documents for BMS are highly detailed, the major purposes of BMS may not be addressed properly. Or they contain requirements that are not helpful or negatively impact the selection process.
The essential aspects to be considered while preparing an RFP/RFQ include:
1) Real-time detection of abnormal battery working condition
Float charging voltage and room temperature are the two most important factors for battery service life.
BMS shall monitor string voltage, cell voltage, charging current, ambient and battery pilot temperature. Abnormal voltage and temperature/ventilation alarms should be handled promptly.
BMS is not designed to interact with the charger for temperature compensation.
2) Reliable detection of heterogeneous battery deterioration
Battery production is a complex and lengthy process, starting from raw material to final product. Shipping, storage, installation, and initial charging can significantly impact battery performance as well.
Even batteries produced in the same batch can have subtle variations in their characteristics. Premature failure is not uncommon for any battery brand, and some cells may deteriorate at a faster rate than others.
To identify abnormal cell(s) in a string, bar graphs for cell voltage and IR (Internal Resistance) are crucial. There are different methods to test IR, but not all of them are suitable for large vented/VRLA batteries used in power plants and substations.
3) Reliable monitoring of battery string continuity
A single bad cell or bad connection can cause battery continuity problems.
BMS must be able to deliver a test current passing through the full string and detect any potential issues. A modular design may not be sufficient for this task, as it may not achieve the required micro-ohm resolution.
A BMS that provides precise and reliable resistance reading for cell-to-cell and inter-tier connections can help to identify torque or corrosion problems in the early stages, allowing for prompt corrective action.
4) Data and trending to evaluate end of battery service life
Evaluating the end of battery service life, replacing cell(s) or an entire string can be a costly decision, and accurate data and trending are essential for making informed choices.
A BMS provider should make this process easier for users by providing necessary data, methodology, and training.
5) Procedure for maintaining the optimal Electrolyte Level
Vented batteries should be inspected routinely (required 4-month interval by NERC, quarterly recommended by IEEE) for maintaining optimal electrolyte level. As of now, there is no device available to water the batteries automatically and precisely. Therefore, investing in ELM (Electrolyte Level Monitoring) has limited value. Waiting for an alarm from ELM may compromise the optimal level requirements.
6) Long-term Reliability
Sentry-6002NEMA is an airtight industrial-grade system allowing for installation in battery room, with a 20+ year designed service life to companion with the best batteries.
A modular system with ventilation in the module and phone jack type connection between modules may be prone to corrosion on the circuit board and connectors in the coming years.
7) Networking and IT Security
BatteryDAQ’s web-based software can be used for both standalone and networked configurations. It has successfully passed IT security scans for deployment in multiple utility networks.
8) Centralized Dashboard
Though all BMS can be connected to SCADA systems, SCADA software is not ideal for battery data access and visualization. Drilling down to a battery bank/cell takes too many steps on SCADA. Data among multiple batteries are not on the same page for comparison. Centralized data and data management tools are critical for successful implementation of BMS.
9) NERC Compliance Reporting
As NERC requires, the report must be submitted/archived every 4 months (or quarterly) with battery data (obtained manually or automatically from BMS).
This process has been simplified and optimized by BatteryDAQ’s 1-click Excel Workbook.
10) Installation and Commissioning
The detailed online MOPs (Method of Procedures) can guide trained technicians for efficient & successful installation, troubleshooting and commissioning.
