High-Voltage Reactive-Power Compensators Based on Semiconductor Voltage Controllers

Approaches to the construction of reactive-power compensators (RPCs) based on semiconductor ac voltage controllers are considered. Alternating-current voltage controllers are implemented that are based on a transformer with a partitioned secondary winding and a semiconductor switchboard constructed on the basis of on controlled switches. When analyzing processes in an RPC, the ac voltage controller can be represented as a transformer with an adjustable transformation coefficient. Electromagnetic processes in an RPC are considered when its power is adjusted within a wide range via control of the transformation coefficient of the transformer. Analytical relationships defining the currents, voltages, and installed power values that characterize RPC power-circuit elements are presented. The fact that the requirements for the parameters of the power switches of a semiconductor switchboard depend on the network voltage is noted. Circuitry solutions are given for RPC design that make the requirements for the parameters of power switches depending on the voltage of the supply network less stringent. Examples of calculating the parameters of 10- and 35-kV RPCs that provide reactive-power adjustment in the range from 0 to 5 MVAR are presented. The simulation results for operating modes of RPCs made on the basis of the proposed circuitry solutions, as well as the results of studies on an RPC prototype providing the adjustment of reactive power in the range from 0 to 5 MVAR when operating powered by a 10-kV network, are compared. The features and advantages of RPCs designed on the basis of semiconductor voltage controllers are described.