Coordinated Control Strategy for Transient Performance Improvement of LCC Based HVDC Transmission System with STATCOM Under Weak AC Grid

Abstract

LCC based HVDC transmission system linked to the weak AC grid suffers from severe operational problems like continuous occurrence of commutation failure and longer fault recovery time during various fault conditions. In order to cope with these operational problems different FACTS devices are used. However, to get better results there is a need of proper coordinated control strategy (CCS) between FACTS devices and HVDC system. This paper presents a novel CCS between LCC based HVDC transmission system and STATCOM. The configured CCS is based on employing extinction angle of the LCC-HVDC system, implementation of drop rate limiter and reactive power control mode of STATCOM. The CCS is developed in PSCAD/EMTDC and various transient simulations are performed in order to validate its effectiveness on transient performance of the study system. The analysis shows that CCS can improve the transient performance of HVDC system by enhancing the commutation failure immunity index (CFII), reducing the risk of occurrence of commutation failure in inverter station and significantly improve the fault recovery performance during single and three phase AC faults.