A Novel Automatic Voltage Control on Large Power System

摘要

Keeping far away from power system instability derived from transient, voltage problem etc. has been thrust into the limelight by the numerous recent blackouts around the world. Coordinated automatic voltage and reactive power control has become a particularly challenging task with the evolution of the electric power industry toward open markets over the last decade which has introduced a number of factors that have increased the possible sources for system disturbances, reduced the robustness of systems, and reduced the predictability of operation. For system operators (ISO or TSO) and many GenGos, it is necessary to build a unified automatic voltage control system (AVC) to balance their different benefits effectively and at the same time achieve significant improvements in power system voltage security, voltage quality, robust and flexibility of system operation. Another motivation is the adaptability that requires the AVC system has the ability to accommodate the development and adjustment particularly in power grid due to the network planning or operation repairment. The advances in relevant technologies present an opportunity to fulfil this vision.This paper presents a novel automatic voltage control on large power system to realize this vision through a new voltage control infrastructure. A three-level hierarchical control structure is used which adopting the successful experiences from several power companies in Europe (such as EDF, RWE etc).However, a new technology of three hierarchical control structure based on online dynamic power network decomposing of secondary control zones is presented. In this new architecture, no fixed secondary voltage controller is needed, and both the secondary and tertiary controllers are implemented by software seamless integrated with EMS in the same control center. With different time constants and control zone division, the voltage control is decoupled, and the multi-objectives about economy, quality and security are coordinated here.Another new technology is the coordination between online optimal power flow (OPF) and online dynamic security assessment (DSA) in Electric Power Alarming and Coordinated Control System (EACCS), a real-time emergency coordinated control system for large-scale power grid, successfully put into operation in Jiangsu Power Grid on June 20th 2007. To prevent from widespread blackout, an OPF schema is consider valid if and only if it can pass through the verification of the DSA. If transient instability or static voltage instability is appeared in advance, an early warning and the appropriated