Advanced control methods and strategies for the Oncor Electric Delivery Renner SVC

Abstract

The Oncor Electric Delivery Renner Substation Static Var Compensator (SVC) project was completed in June, 2010 and consists of two parallel connected SVCs each with an installed capacity of -265 MVAr to +300 MVAr at 138 kV. The total rated capacity at the Renner 138 kV bus is -530 MVAr to +600 MVAr, making it one of the world's largest SVCs - the other is at the Oncor Parkdale Substation and is of identical rating. Based on operating experiences with the Parkdale SVC, advancements to the control methodologies and control strategies have been implemented in the Renner SVC. These consist of advances in the control functions for reactive power control, overload capability, and protective control functions. The SVC control system platform is a microprocessor based control system using the ABB MACH2 concept. Dedicated voltage and current transformers installed at the Renner 138 kV substation bus provide the control system with the power network variables utilized in the SVC control. The control system provides facilities for SVC operation from the Operator Work Station (OWS) located in the SVC control room, or remotely via a GWS to a conventional RTU/SCADA system. The SVC control system is structured around two main modes of operation: (1) Automatic Voltage Control and (2) Manual Control. In particular, the main advancements employed in the control system methodology for the Renner SVC consist of a TSC blocking function for both symmetrical and unsymmetrical conditions, and a gain optimization feature in conjunction with the gain supervision. In addition, the SVC control provides coordinated control of external capacitor banks, ability for reduced modes of operation in the case of branch failures, loss minimization functionality, and parallel operation of the SVC through a `master/follower' feature, as well as various protective control functions. The strategy and operation of the advanced features for TSC blocking and gain optimization are discussed further in this paper, along with the other control system functions and overall operational strategy for the Renner SVC.