60MWh DC-Side Energy Storage System Solution

1. Project Overview

This solution is designed for the construction of a 60MWh lithium iron phosphate energy storage system consisting of 12 standard 5MWh liquid-cooled battery containers. The system is connected to the grid at 35kV voltage level, mainly applied for grid-side peak shaving, renewable energy supporting facilities, or large industrial and commercial users. Adopting the DC-side parallel connection scheme, the DC sides of the 12 battery containers are collected and connected to the DC side of PCS (Power Conversion System), which reduces AC circulating current and improves system efficiency.

2. Core Product Parameters

The energy storage container system adopts 314Ah battery cells, with battery PACKs configured in a 2P52S series-parallel connection. Each battery cluster includes 8 PACKs and is matched with 1 high-voltage box. The DC circuits of 6 battery clusters are integrated to the isolating switch of the collection and control cabinet to form 1 DC high-voltage circuit. Each energy storage container is equipped with 1 DC high-voltage circuit, as well as auxiliary equipment such as liquid cooling unit, dehumidifier, BMS (Battery Management System) and fire protection system.

2.1 Main Component Configuration of Energy Storage Container

Table 1 Main Component Configuration

2.2 Key Technical Parameters of Energy Storage Container

Table 2 Key Technical Parameters

3. PCS and Step-up System Parameters (Configured by DC-side Scheme)

Table 3 PCS and Step-up System Parameters

4. Station Topology

4.1 Description of Main Electrical Wiring Topology

Battery Array: 12 units of 5MWh containers, divided into 6 groups (2 units per group).

DC Current Collection: The 2 battery containers in each group are connected in parallel through the DC circuit breaker cabinet and connected to the DC bus (DC 1500V).

Inversion Unit: The DC bus is connected to 1 unit of 5MW PCS.

Step-up and Grid Connection: The AC output of PCS is connected to a 5MVA transformer (0.315/35kV), and connected to the 35kV bus through the high-voltage switch cabinet after step-up.

4.2 Station Topology Diagram

(Attachment: Topology Diagram of 60MWh DC-Side Energy Storage Station)

5. Construction and Installation Scheme

5.1 Civil Foundation Phase (Approx. 30 days)

Site Leveling: Compaction treatment for the estimated 100m x 80m site, with the requirement of ground bearing capacity > 10t/m².

Foundation Pouring:

• Battery container foundation: Adopt strip foundation or independent bearing platform with pre-embedded cable trench sleeves. The foundation surface height must be higher than the local 50-year flood level or water accumulation level.

• Cable trench: Set up longitudinal and transverse cable tunnels for laying DC cables (attention to separation of strong and weak current).

Grounding Grid: Lay hot-dip galvanized flat steel to form an annular grounding grid with grounding resistance < 0.5Ω.

5.2 Equipment Installation Phase (Approx. 20 days)

Container Hoisting:

• Use a 150-ton mobile crane for unloading and positioning.

• Installation sequence: Hoist the remote containers first, then the near ones to avoid path obstruction.

• After the container is positioned, calibrate the level with a laser level, then fix it (welding or clamping of anchor bolts).

High-voltage Equipment Installation:

PCS and transformers are generally integrated in the step-up cabin (or independent platform) for busbar connection and insulation testing.

Cable Laying:

• DC cable: Adopt special DC cable with a voltage resistance of DC 1.8kV (e.g., YJV-1.8/3kV), with attention to the color distinction of positive and negative poles (red/black) and lightning protection grounding.

• Communication cable: Lay Category 6 shielded network cables or optical fibers along the special bridge of the cable trench, with a distance of > 300mm from the power cable.

5.3 Commissioning Phase (Approx. 15 days)

Single Unit Commissioning: Test the BMS communication, battery cell voltage and internal resistance, and fan start/stop of each battery container one by one.

System Commissioning: PCS no-load operation -> PCS on-load operation -> EMS (Energy Management System) logic test (charging and discharging response time < 40ms).

Grid Connection Test: Conduct anti-islanding protection test and power qua

6. Detailed Technical Parameters

6.1 Battery System

• Cell Specification: 3.2V / 314Ah (1C charge/discharge, energy density > 165Wh/kg)

• Assembly Mode: 2P52S (one battery PACK, voltage 166.4V) -> 8 battery PACKs in series (container voltage 1331.2V)

• Energy Efficiency: ≥ 94% (including auxiliary power consumption, 0.5C charge/discharge)

• SOC Accuracy: ≤ 3%

• Auxiliary Power Supply: AC 380V, 50Hz, power consumption of each container is about 8kW (during cooling)

6.2 PCS System

• Topology Structure: Three-level IGBT topology

• Efficiency: ≥ 98.5% (including transformer)

• Response Time: ≤ 30ms

• Cooling Mode: Air cooling / Liquid cooling (customized according to manufacturer)

• Protection Functions: DC overvoltage, AC overcurrent, insulation detection, anti-islanding protection

6.3 Monitoring and Communication

• Communication Protocol: IEC 61850 (power station level), Modbus TCP/IP (internal system)

• Main Equipment: BMS (Battery Management System), PMS (Power Management System), EMS (Energy Management System)

• Data Collection: Single cell voltage and temperature; single battery cluster current; grid connection point frequency and harmonics.

7. Maintenance and Servicing Scheme

7.1 Daily Inspection

Table 4 Daily Inspection Items

7.2 Regular Special Maintenance

Table 5 Regular Special Maintenance Items

7.3 Emergency Response Plan

7.3.1 Thermal Runaway Alarm

1. Immediately disconnect the DC circuit breaker of the faulty cluster.

2. Start the exhaust system (if designed for smoke exhaust).

3. Confirm personnel evacuation and remotely start the perfluorohexanone/heptafluoropropane fire extinguishing device.

4. If the fire spreads, dial 119 and start the water spray system (ensure the electrical system is powered off to prevent electric shock).

7.3.2 Grid Fault

In case of grid flashover or frequency mutation, the PCS shall automatically switch to standby or grid-forming mode to support the grid. After the fault, check whether the PCS IGBT modules are damaged.

8. Project Economic Indicators (Estimated)

Table 6 Project Economic Indicators