Investigation And Study Of Plant Reactive Power And Voltage Control Mode

With the rapid development of computer technology, automatic control technology and communication technology, the automation of power system has been greatly improved, and the control of reactive power and voltage in power plant has also been developed considerably: from Automatic Voltage Regulator(AVR) which fixating unit’s terminal voltage in excitation system, to reactive power closed- loop control module that setting unit’s reactive power in monitoring system, and then to Automatic Voltage Control(AVC) system which controlling the high bus voltage in plant and multi- level automatic voltage control system of the entire power systems. The level of power plant automation is not the same due to the difference of plant construction period, leading to the presence of a variety of reactive power and voltage control modes. Voltage over- limit event of N iuzhai converter station in August 31, 2013 and voltage abnormal event of Yantan plant in January 21, 2014 both exposed the security risks of individual voltage control modes. Therefore, carding existing plant voltage control modes comprehensively, comparing the characteristics of voltage control mode and its imp act on grid operation, investigation and analysis of actual power grid, have positive meanings for reducing risks of power grid.Seven major plant voltage control modes are teased out, voltage control principle of plants in a variety of modes are introduced. Voltage over- limit event of N iuzhai converter station due to single generator’s reactive closed-loop control mode of Xiluodu power plant and Yantan voltage abnormal event caused by bugs of AVC are analyzed in details. The impact of the grid operation in three most common local control modes are simulated and analyzed from the voltage control and voltage stability. According to the simulation results which further confirms the security risks of the single generator’s reactive closed-loop control mode, an improved single generator’s reactive closed- loop control mode is proposed. This mode neither increased labor costs caused by exiting reactive closed- loop control mode completely, but also to ensure running in security.For risks the single generator’s reac tive closed- loop control mode may cause, an investigation about plant reactive power and voltage control mode is conducted in CSG. Survey results show that: there are 33 220 k V and above plants use the reactive closed- loop control mode in CSG as of the end of October 2013. Meanwhile, The results of the survey about plant voltage control mode within CSG is analyzed, and some improvements are given.Finally, a comprehensive evaluation of power plant AVC demand method based on AHP is proposed, and the method is applied to evaluation of immediate dispatch plants’ AVC demand in CSG including the power dispatching control centre of headquarters and each province. the evaluation can provide a scientific basis for CSG to make decisions about construction of plant AVC system and priority of accessing AVC master.