Research On High-voltage Reactive Power Compensation Method Based On Magnetic-controlled Switch

With the development of industry and distributed new-energy generation, the voltageprofile and power quality has been increasingly concerned. High voltage TSC is quick indynamic response and harmonic-free. However, its thyristor-valve banks consist of20serialized triacs per phase, which leads to poor reliability and huge cost, so that it is seldomapplied for medium capacity compensation. High voltage SVC (FC+MCR or FC+TCR)works in a ’reverse manner’, which results high power consumption when requiredcompensation capacity is low or zero. High voltage SVG is built up by too many serializedblocks, and its control system is quite complex, so that the reliability cannot be assured.Based on the specialties of reactive power compensation in high-voltage distributionsystem, a novel compensation method founded on Magnetic Controlled Switch (MCS) isproposed. MCS is composed of triacs which are connected in parallel with the secondarywinding of a transformer as switching components. By turning on of turning off the triacs,the transformer is either no-load or short-circuit, so that the compensation branch becomeseither a no-load branch, or a compensation branch. In this way, the no-transient switch ofcompensation branches under high voltage is implemented. The whole compensationsystem consists of several parallel branches which are put in according to the need ofreactive power.The principles of this novel method is discussed and analyzed in details, based onwhich the key parameters of the main circuit are analyzed and calculated. PSCAD/EMTDCis applied to simulate all possible operation conditions, and the simulation results haveverified the advantage of this novel method under medium capacity (10MVar level).According to theoretical analysis and simulation results, a10kV/1200kVar testprototype is built while a35kV/1000kVar test prototype is now under building. The designof main circuit parameters, control system and control program are done in this essay. Theexperiments have verified the correctness of theoretical analysis and the effectiveness ofsimulation. This novel method is quite suitable for reactive power compensation atphotovoltaic plants and wind-farms, etc.