Protection Centralization of a Direct Connect Static Var Compensator

American Electric Power (AEP) owns the nation’s largest electricity transmission system,operating a more than 40,000-mile network that includes more 765-kilovolt extra-high voltagetransmission lines than all other U.S. transmission systems combined, more than 223,000 milesof distribution lines, and producing approximately 30,000 megawatts, including more than 5,300megawatts of renewable energy [1]. AEP also operates and maintains approximately 30 FlexibleAlternating Current Transmission System (FACTS) and High Voltage Direct Current (HVDC)sites. This paper focuses on a FACTS site with a Static Var Compensator (SVC). SVCtechnology is well explained elsewhere[2] and will only briefly be discussed here. An SVC willoften be found to be made up of bus-work, coupling transformers, Thyristor Controlled Reactors(TCR), Thyristor Switched Capacitors (TSC), and harmonic filter banks. This equipment can befound alongside ancillary secondary systems that are required to operate this equipment likecooling, valve, control, and protection systems. Though not all this equipment is required forevery SVC manufactured, a subset of these components will be found at any SVC. The SVC ofstudy in this work is made up of 69kV bus-work, a single TCR branch, and three harmonic filterbanks (single tuned at the 5th, 7th, and 15th harmonic). A simplified single line diagram of theSVC can be found in Fig. 1. As can be seen in Fig. 1, the harmonic filter banks offer a capacitive range of the SVC of 50MVar and the TCR, in conjunction with the harmonic filter banks, offersan inductive range of 40MVar.