A static var compensator is composed of switching reactors and capacitors controlled by thyristors. Since thyristors respond extremely quickly to control signals, and the number of on-offs can also be unlimited. When the voltage changes, the static var compensator can be adjusted quickly and smoothly to meet the needs of dynamic var compensation, and at the same time it can achieve phase-separated compensation; it has strong adaptability to three-phase unbalanced loads and impact loads ; However, since high-order harmonics will be generated during the switching process of the reactor controlled by the thyristor, a special filter needs to be installed for this purpose.
In recent years, with the continuous increase of high-power nonlinear loads, the reactive power impact and harmonic pollution of the power grid are on the rise. The lack of reactive power adjustment means makes the bus voltage change greatly with the change of operation mode. This leads to an increase in the line loss of the power grid and a decrease in the voltage qualification rate. In addition, with the development of the power grid, the issue of system stability is becoming more and more important. Dynamic reactive power compensation technology is an economical and effective measure to improve voltage stability. In addition, the objective demand for static var compensation technology in wind farms, metallurgy, electrified railways, coal and other industrial fields is also great.
In the current situation, the static var compensator is an effective method to solve the reactive impact generated by various loads. It can significantly improve the grid voltage fluctuation and power factor. It is a new type of energy-saving device with high technical content and significant economic benefits. Thyristor converter and control system can realize this function. Collect the reactive current value and voltage value of the bus, synthesize the reactive value, compare it with the set constant reactive value, and calculate the size of the firing angle.
Static var compensator refers to the use of different static circuit breakers to switch capacitors or reactors, so that it has the ability to absorb and send out reactive current, and is used to improve the power factor of the grid, stabilize the grid voltage, and suppress system oscillation. device. The inductive reactive power equipment in most static var compensation devices can realize stepless continuous adjustment, and the capacitive reactive power equipment can be adjusted in stages to realize static, fast and continuous stepless provision of capacitive or inductive reactive power to the grid, reaching Improve the quality of voltage in an all-round way, meet the purpose of power supply requirements, and also reduce the active power loss of the power grid, improve the stability of system operation, and reduce the power frequency overvoltage.