1.1 project overview

Huaneng Shanxi Dongmafang wind farm phase III project is connected to 110kV busbar through 35kV/110kV main transformer for grid connection, and the fan inverter is connected to 35kV bus through box-type transformer. Due to the instability of wind power generation, relevant national regulations require that the grid connection point voltage at the high voltage side of the station should be controllable, and the station should be equipped with dynamic reactive power compensation equipment to control the system voltage. The actual SVG device of the project is shown in Figure 1.1, and the project was put into operation in 2016.

Figure 1.1 photos of SVG equipment of Huaneng Dongmafang project

1.2 Technical scheme

This project adopts the centralized management mode of system voltage, and is equipped with SVG equipment under 35kV busbar. SVG equipment can dynamically control the system voltage in real time according to the  voltage command set, and the voltage command is sent to SVG controller remotely by AVC control system.

The SVG equipment detects the busbar voltage of 110kV side in real time, and the received AVC command is taken as the voltage control target for closed-loop control.

1.2.1 SVG equipment information

SVG rated voltage: 36.75 kV (designed according to actual busbar rated voltage)

SVG rated capacity: ± 16 Mvar (according to 20% - 40% of the wind farm installed capacity)

SVG connection mode: wye-connection

1.2.2 SVG main circuit topology

The topology of the main circuit is shown in Figure 1.2. After cascading, the SVG modules are directly connected to the 35kV busbar through the connecting reactor.

1.3 Application effect

Figure 1.2 shows the set value of voltage command (the command is given by AVC system), the actual voltage of the system and the reactive power output by SVG.

Figure 1.2 system voltage control curve