Grid application cases

[Project] State Grid Yueqing Power Supply Company Hongqiao Town 10 kV line side energy storage project (Yueqing, Zhejiang, put into operation in September 2020)

1 Project background

• Regional pain points: Xixi Industrial Zone in Hongqiao Town has high peak loads in summer, heavy overload of 10 kV lines, and tight resources in traditional expansion channels and substations.

• Construction goals: Utilize fixed-point energy storage on the line side to "cut peaks and fill valleys, and dynamically increase capacity" to reduce the peak current of 10 kV lines, improve power supply reliability, and reduce rigid investment in distribution networks.

2 Project scale and access

• Energy storage capacity: 1 MW / 2.088 MWh (lithium iron phosphate)

• System composition: 4 units of 250 kW / 522 kWh container-type energy storage subdivisions

• Voltage level: AC side 10 kV directly connected to the grid, and merged into the Xixi II return line through the T contact

• Operation strategy: “3 charges and 3 discharges per day” in summer, discharge depth 90%, cycle life ≥ 6000 times

3 Technical parameters of energy storage equipment

Subsystem detailed parameters

Battery type Lithium Iron Phosphate (LFP)

Rated power/capacity 1 MW / 2.088 MWh (0.48 C)

Battery pack 280 Ah cells → 1P16S module → 8 modules/cluster → 14 clusters/pod

522 kWh per cabin, rated 250 kW PCS

PCS three-level topology, efficiency ≥ 96%, four-quadrant operation, supports primary frequency modulation

BMS three-level architecture, SOC accuracy ≤ 2%, active balancing

Cooling method Industrial air conditioning + air cooling, cabin 25 ℃ ± 3 ℃

Fire protection system perfluorohexanone gas fire extinguishing + smoke temperature composite detector

Response time: On-grid to off-grid < 100 ms, one frequency modulation ramp 1 MW/min

Communication interface IEC 61850 + GPRS/4G, dispatching direct procurement

Warranty period Battery ≥ 8 years or 6000 cycles

4 Operation results

• Peak shaving capability: The peak value of a single circuit line is reduced by 600 A, which is equivalent to saving investment in 8 km of 10 kV lines and a 20 MVA distribution transformer.

• Economic benefits: Peak and valley arbitrage + demand electricity cost savings in the first year of operation ≈ 1.2 million yuan.

• Power supply reliability: The number of power outages due to line faults dropped by 42% year-on-year, and the average annual power outage time for users was shortened by 3.2 hours.

5 project highlights

• China’s first 10 kV line-side fixed-point energy storage demonstration, verifying the “source-grid-storage” interactive model;

• Modular container design with a construction period of only 30 days, supporting rapid relocation and capacity expansion.