The Development Of A New Voltage-Reactive Power Integrative Control Equipment

The voltage & reactive power control (VQC) device, which regulates transformer's on-load tap changer and shunts capacitors in power substation, is one of the most important means used for voltage & reactive power optimization and control. It is of great significance for improving electric energy quality, guaranteeing power system security and economical operation.Most of recent VQC devices in operation are based in the traditional 'nine-zone diagram' control strategy, which occurs some problems, such as too many times of adjusting on-load tap changer and capacitors and causing oscillation, etc. Aiming at the shortages of the 'nine-zone diagram' control strategy, this paper puts forward a new method that combines traditional 'nine-zone diagram' control principle with ultra-short term load forecasting and fuzzy control strategy. In the new method, ultra-short term load forecasting is introduced to get the trend line of voltage and reactive power at the substation, and then to minimize the times of regulating transformers and capacitors with eligible voltage and power factor (or reactive power). However, in the case of lacking of historical load data on which the forecasting is depended, or when the forecasting result is not precise enough to get satisfactory control effect, the ultra-short term load forecasting method should be substituted by real-time control on the basis of 'nine-zone diagram' fuzzy strategy to guarantee satisfaction of the control result under all situation.On the basis of the new control method mentioned above, and according to the technology demand and control function of VQC, a new VQC device based on IPC hardware platform and Windows operating system has been developed, and the design of its hard- and software is detailed. The results of both testing and operating of the sample device indicate that the regulating method and control strategy is reasonable, accurate and reliable. It can solve the problems such as low control efficiency, 昬xcessively frequent regulating and unfriendly interface that result from the limitation of control strategy and hardware in the previous VQC devices. The performance of the device meets the operating need of substations and has reached the request of practical operation.