Current-based Capacitor Overvoltage Protection of Static Var Compensator
In static var compensators with series reactors,there is installed no voltage transformer at both ends of capaci-tors,resulting in inadequate accuracy in capacitor overvoltage protection.To address this problem a current-based har-monic overvoltage protection for shunt capacitors is proposed.First the currents of the capacitors are measured to calculate the harmonic currents by Fourier algorithm.Second the relationship between fundamental wave,harmonic current,and voltage of capacitors is derived,and the harmonic voltages of the capacitors are caculated based on derived formulas.Final-ly the derived formulas are verified through simulation software,and the method of realizing capacitor harmonic overvolt-age protection by digital relay is explained.The results show that the theoretical derivation of this method is consistent with the actual simulation results,and it improves the reliability of capacitor overvoltage protection.
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