Application of iSVG Device in Solar Power Industry

The 30MWp photovoltaic power generation project of Huancui mountain, Datangtianzhen is located in 2.0 km northwest of Guqianbao town of Tianzhen County. The project uses 240Wp polysilicon solar cell module. Each unit is used as a power generation unit. There are 30 power generation units, totaling 30MWp. After the project is put into operation, it is expected that the average annual electricity consumption will reach 42365MWh. Compared with the corresponding environmental protection measures taken by coal fired power plant, it can save 13.5 million tons standard coal for our nation every year, and reduce the emission of various harmful gases and exhaust gas, it has a great significance for relieving energy crisis and environmental pressure.

The solar power station adopts 10kV / 35kV step-up and parallel grid mode, there are 6 solar branches in the 10KV side, SVG are connected in parallel to 10kV bus circuit, and SVG collects the voltage and current signals in the main transformer's high and low voltage side respectively. And it takes the voltage and reactive power in the main transformer's high and low voltage side as control goal to achieve automatic control function.

According to the parameters provided by project, the project needs to configure ± 7.5MVar reactive power compensation capacity, iSVG device can achieve continuous rapid adjustment from inductive reactive power to capacitive reactive power range of -7.5 ~ 7.5MVar, the final choice of iSVG-7M5-10 -CT can meet the project requirements. Soalr station main circuit primary system diagram is shown in Figure 2.

Figure 2 Soalr station primary system diagram

iSVG is required to access the solar station integrated automation platform to meet the requirements for dispatch center remote control and remote adjustment. Automation platform and iSVG communication standard adopt standard MODBUS communication protocol to achieve the voltage, current, power unit status information detection of iSVG device via the background, realizing remote adjustment device reactive or voltage control objectives, as shown in Figure 3.

Figure 3 The realization of iSVG automation control

ISVG device takes 35kV bus voltage as the control target, and real-time tracks grid voltage changes and reactive power changes, according to changes demands, dynamically adjust the device reactive power output. Huancui mountain solar power station takes controlling voltage command as the control target, requires the total discharge voltage of soalr station to follow the scheduling voltage command changes. After adding the iSVG series high-voltage static reactive power generator, the grid voltage is effectively controlled, from the voltage curve shown in Figure 3, we can see that iSVG real-time tracks the given target voltage to adjust the grid voltage and meet the control requirements.

Figure 4 Solar station voltage adjustment curve