10 kV equipment energy storage

Energy storage technology has become critical for supporting China's large-scale access to renewable energy. As the interface between the battery energy storage system (BESS) and power grid, the stability of the PCS (power conversion system) plays an essential role.

Table 1. Simulation parameters. Among them, the rated voltage of the power grid is 10 kV and the frequency is 50 Hz. The HVAC part of the energy storage PCS system contains 15 modules in each phase, with a three-phase Y-connection.

Large-scale energy storage is favorable currently. The capacity expansion needs to be realized by the parallel connection of multiple low-voltage small-capacity PCSs and connected to a medium- or high-voltage power grid through the transformer. The connection would lead to the problems of low efficiency, high cost and unnecessary land occupation.

The source drain voltage of the device is V ds = 1.2 kV, and 15 modules are used for each phase in series for 18 kV, meeting the insulation requirements of the 10 kV voltage level. The rated capacity of each module is 23.8 kW, and the rated through current is about 34 A, with a sufficient through current margin. Figure 15. PCS prototype.

Energy storage can solve the power grid's requirements of transient stability and short-term power balance and can be used for long-term power regulation. It can effectively deal with the systemic peak valley regulation and blocking of transmission and distribution lines [ 1, 2 ].

The peak value of transient overvoltage at the LVDC side is about 720 V and overshoot is about 0.02%, and the peak value of transient overcurrent at the LVDC side is about 480 A and overshoot is about 68.4%, which is within the allowable range. Under the condition of 20% rated power, the output current THDi is 3.31%, as shown in Figure 8. Figure 7.