Development and applications of system-wide automatic voltage control system in China

Traditionally voltage control is done in a decentralized way at the power plant or substation level in China. Such a traditional mode, lacking of automatic coordination in a system level, is no longer fit for the higher requirements of security and economy of modern large power system operation. In recent years, development and field site applications of close-looped system-wide automatic voltage control (AVC) technique were actively done in China. In the paper, a novel control architecture based on online adaptive network zone division is proposed. Logically such a system is in a three level hierarchical structure, however, both secondary voltage control and tertiary voltage control here are implemented with software in a control center, and the control zones are no longer fixed according to variation in power systems, which is more suitable for the fast developing Chinese power grids. Some key techniques implemented in the AVC system are introduced, such as adaptive zone division, strategies of Tertiary Voltage Control (TVC), strategies of secondary voltage control (SVC), etc. Finally some field experiences, especially some results not from simulation tool but from field site applications, are reported. The excellent performance of the AVC system and significant improvements on power system security and economy are validated. The developed AVC system has been applied to more than a dozen control centers in China, such as the North China Power Grid with generating capacity of 119GW. Evaluation of the potential profits of the proposed AVC system on PJM system in USA is ongoing.