Analysis of 48-pulse based STATCOM and UPFC performance under balanced and fault conditions

Convertible Static Compensator (CSC) which is a versatile Flexible AC Transmission System (FACTS) technology has been installed on Marcy 345 kV substation and increases power transfer capability, operational functionality, and power flow controllability of the New York Power Authority (NYPA) transmission system. This paper presents a comprehensive description of CSC inverter 48-pulse wave construction along with introduction of control strategy deployed in CSC when it is operating as a STATCOM and UPFC. STATCOM and UPFC steady state and dynamic operation PSCAD simulation results under different testing conditions including unbalanced condition and faults are presented. This paper also provides comprehensive analysis of the STATCOM response to negative sequence and harmonic voltage components on the transmission line during fault conditions. The amounts of DC-link capacitance that lead to maximum and minimum of fundamental negative sequence current on the tie line and 120 Hz oscillation on the DC-link voltage are calculated. Simulation results of STATCOM performance with different DC-link capacitance during fault condition will be shown. At the end of the paper, one exiting problem regarding to UPFC operation of NYPA CSC has been addressed and illustrated with precise simulation results.