Project Partners
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Project Overview
TATA Power in India encounters challenges with energy backups during both planned and unplanned transformer maintenance. This often necessitates temporary electricity outages, disrupting the operation of the electrical network. To mitigate this issue, a mobile substation battery energy storage system (BESS) has been designed and developed by StorTera in accordance with TATA Power’s technical specifications. This system enhances grid resilience by providing flexible, mobile support to various substations within the region, thereby ensuring a continuous power supply and minimising service interruptions.
Project Aims
The project aims to develop a robust, mobile BESS tailored to TATA Power’s needs. The initiative began by defining comprehensive design requirements through iterative collaboration with TATA Power to establish system constraints and functional specifications. A trailer-based design was ultimately selected over a truck-mounted alternative. StorTera leads the system design, integrating the battery, power conversion system, and container. The system’s performance is tested at PNDC to assess its ability to support distribution transformers during planned maintenance and outages, while also providing ancillary grid services when stored at the depot. Subsequently, the system is shipped to the Indian Institute of Technology Roorkee (IIT) Roorkee in India, where StorTera’s power conversion system is replaced with a newly prototyped version developed by IIT Roorkee and scaled by an Indian industrial partner. Finally, a field trial will be conducted in India, connecting the mobile BESS directly to a TATA Power transformer to validate its performance under real-world conditions.
PNDC’s Role
PNDC conducted testing of a 100 kW BESS to assess its capability to support transformers during maintenance and outages, thereby enhancing grid resilience. Leveraging expertise in performance benchmarking and risk assessment, PNDC ensured the BESS met technical and safety standards by evaluating key functionalities such as efficiency, Total Harmonic Distortion (THD), overcurrent protection, blackout recovery, dynamic load support, grid connectivity, and response to over/under-voltage and frequency fluctuations. PNDC’s in-depth knowledge of Control of Substances Hazardous to Health (COSHH) regulations ensured the safe handling of battery materials, mitigating potential chemical hazards. Furthermore, PNDC’s efforts contribute to developing industry best practices for integrating BESS technology into grid infrastructure, promoting safer, more reliable, and scalable energy networks.
The PNDC team undertook the following tasks:
Developed a comprehensive test plan aligned with the client’s requirements.
Performed BESS testing at the PNDC facility in accordance with project timelines.
The BESS achieved a 90.73% AC round-trip efficiency, slightly exceeding the planned 90%, possibly due to early-cycle testing.
Voltage tests deviated from G99 standards due to the mobile substation system’s configuration, and frequency tests confirmed BESS operation within India’s typical ±1% frequency range.
Overcurrent tests demonstrated that the BESS could handle 144 A continuously and sustain 154 A for 29 seconds before tripping, consistent with its design specifications.
The PNDC assets utilised during the project included:
Substation A, LV feeder pillar No.3, Load banks, Fluke Power Analysers, Motor Generator, current clamps
Project Outcomes
The test results are categorised into BESS capabilities and basic function performance.
In on-grid mode, the BESS successfully supported the grid at 97 kW for 1 hour and 15 minutes, aligning with the test plan, though performance under winter conditions was 16 minutes shorter due to elevated cell temperatures.
Dynamic load testing confirmed reliable scheduled power delivery, while off-grid tests demonstrated 3-hour support at unity power factor, with voltage and current THD values remaining within IEEE and IEC standards.
Basic function tests showed voltage and current THD remained within international limits across various load scenarios, although non-linear load effects, likely originating from the PCS, resulted in higher THD levels when the battery was idle.
The BESS achieved a 90.73% AC round-trip efficiency, slightly exceeding the planned 90%, possibly due to early-cycle testing.
Voltage tests deviated from G99 standards due to the mobile substation system’s configuration, and frequency tests confirmed BESS operation within India’s typical ±1% frequency range.
Overcurrent tests demonstrated that the BESS could handle 144 A continuously and sustain 154 A for 29 seconds before tripping, consistent with its design specifications.
Impact
PNDC’s contributions to the project were as follows:
Provided a controlled and realistic testing environment to evaluate the BESS under various scenarios, including on-grid, off-grid, and dynamic load conditions.
Ensured BESS performance aligned with international standards such as IEEE 519-2022, IEEE 1547, and IEC 61727.
Identified key performance factors, including:
The impact of high cell temperatures on discharge rates.
The BESS’s capability to manage frequency and voltage fluctuations within grid limits.
Detection of non-linear load effects from the PCS causing increased harmonic distortion during idle battery states.
The impact of high cell temperatures on discharge rates.
The BESS’s capability to manage frequency and voltage fluctuations within grid limits.
Detection of non-linear load effects from the PCS causing increased harmonic distortion during idle battery states.
Offered valuable insights that facilitated system improvements, enhancing reliability and efficiency.
Ensured precise and transparent testing processes, reinforcing the credibility of results presented to the client.
Aided in validating the BESS’s performance, thereby accelerating its readiness for deployment, particularly in the Indian market.
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