A SYSTEMATIC APRROACH FOR FAULT DETECTION AND LOCATION IN HVDC TRANSMISSION LINE USING WAVELET TRANSFORM

Transmission of electrical power through High Voltage Direct Current (HVDC) system has no doubt first choice for the long transmission of electricity all over the world .The HVDC transmission system having important parameters like controllability of power flow, economy while transmitting bulk power over very long distances, lower transmission losses and absence of stability issues. Thus the HVDC transmission system is preferred in almost all cases where bulk power needs to be transmitted over 500 km and above. The major faults associated with HVDC transmission system are dc line to ground fault, faults on the ac side of the inverter, commutation failure at the inverter. The protection principle based on travelling wave theory provides the fastest protection. Long HVDC lines can be modeled using distributed elements. According to Travelling Wave Theory, when the fault occurs on the transmission line the voltage and current travelling waves appear on the line. The travelling waves generated will carry information related to the condition of the transmission system. In this paper, the behaviors of different faults in HVDC power systems will be analyzed through wavelet transform and the protection criterions based on wavelet technique will be Proposed. The protection can detect the HVDC line fault well and identify the HVDC line fault clearly