Study Of Dynamic Reactive Compensation System In Distribution System

With the rapid development of power electronic technology, more andmore power electronic devices are applied to various fields, most of which arenon-linear loads, and bring more and more serious pollution to the power grid,so real-time reactive power compensation and harmonic suppression isbecoming increasingly important. STATCOM was brought out during1970sas a new type of dynamic reactive power compensation device, and it hassome advantages: fast response, good compensation effect and dynamiccompensation, when compared with the traditional reactive powercompensation devices.This article compares STATCOM with traditional reactive powercompensation devices simply, and describes the development、application、classification and principle of STATCOM. The reactive and harmonic currentdetection algorithms: p-q algorithm and the ip-iqalgorithm, which are basedon instantaneous reactive power theory, are analysed. The indirect control anddirect control strategies of current are introduced and compared, and theircharacteristics are compared through theoretical analysis. And the hysteresiscontrol based on space vector, which is rapidly developed recently is analyzedimportantly.DSP-based Digital dynamic reactive power compensation device isdesigned on the theoretical analysis, whose hardware is introduced in detail,including the controller selection, the sampling circuit, the interlock logicdelay circuit, the optocoupler driver circuit and the main circuit. The systemsoftware is completed, including the instantaneous current sample, theinstructions current calculation and the control algorithm, which are alldesigned through the interrupt programs of DSP. In order to improve thesystem’s real-time, the C and assembly languages are mixed during theprogramming. The development of the experimental prototype was completed, and a preliminary experimental study on the STATCOM device was finished.