High voltage chain SVG static var generator FREL-SVG-(20Mvar/10)-F
1. Topological structure of high voltage chain SVG
Topological structure: cascaded H-bridge circuit increases output voltage, avoids series connection of low switching frequency to achieve low harmonic output 60 ~ 1000kHz, reduces dv/dt and reduces EMI
The main circuit is composed of high-power power electronic devices (such as IGBT, GTO, etc.) that can be turned off; grid-connected filter to reduce output current ripple; grid-connected transformer to match the voltage level between the output and the grid.
Secondary circuit: including sampling, control, driving, etc.
3. Composition of high-voltage chain SVG: reactor cabinet (charging cabinet), power cabinet and control cabinet.
(1) Control cabinet;
(2) Reactor cabinet (charging cabinet);
4. The SVG control cabinet of our company has the following characteristics:
Two independent power supplies are used in the control cabinet to supply power to the control system (redundant design) to ensure the reliability of the system's power supply;
The main controller adopts large-scale integrated circuit and surface welding technology, and uses automatic welding equipment for welding and needle bed testing for inspection, which greatly eliminates the influence of instability caused by manual participation, and the system has extremely high reliability;
The control core of the main controller is realized by a high-speed 32-bit digital signal processor DSP and a large-scale programmable device FPGA cooperative operation to ensure that the high-voltage SVG reaches the optimal operating performance;
The I/O port of our company's high-voltage SVG is directly integrated into the control system as a part of the entire control system, and each part of the function is independently developed by Fei Lai, the response speed is in the microsecond level, usually less than 100 microseconds; domestic part The company's control system uses PLC because their own control system I/O ports are not enough, and the control system is lacking. Due to the limited response speed of the PLC, it is generally in the millisecond level, which greatly reduces the response time of the complete device.
5. The advantages of our company's high-pressure chain SVG
The I/O port of Fei Lai's high-voltage SVG is directly integrated into the control system as a part of the entire control system, and each part of the control function is independently developed by Fei Lai. The response speed is in the microsecond level, usually less than 100 microseconds; The branch company’s control system uses PLC because their own control system I/O ports are not enough and lack the control system. Due to the limited response speed of the PLC, it is generally in the millisecond level, which greatly reduces the response time of the complete device;
Adopt comprehensive protection strategies: device-level protection, device-level protection and system-level protection:
Device-level protection: the protection action time limit does not exceed 10us, and the protection can be implemented quickly when the device is found to be over-current, over-voltage or abnormal in the drive signal;
Device-level protection: the action time limit is 500-1000us, and the protection can be implemented quickly when the device is found to have abnormal conditions such as overload and high DC voltage;
System-level protection: The action time limit is 5ms. When the system loses voltage, the system voltage is too high, or the cooling system malfunctions, the protection is implemented quickly.
The compensation current resolution is 0.1A;
The minimum starting current is 3A;
THD around 2%;
The DC side voltage fluctuates about 50V;
Small device loss: ≤0.8%;