Research Of The Valt/Var Control Method On Plant-grid Coordination Based On Improved Area Reactive Power Sharing Method

Automation Voltage Control(AVC)sysytem is an indispensable means to keep the grid operation under security,reliability and economy.With the continuous expansion of the operational scale of power grid,the increasing complexity puts forward higher requirements on the AVC system.Based on the analysis of the application status of AVC control methods in substations and power plants,this paper points out the deficiencies on their optimizations and coordinations.According to this,this paper put forward a Volt/Var control strategy under plant-grid coordination based on an Impoved Area Reactive Power Sharing Method(IARPSM)to realize the differential and optimizing control on plants and substaions ' reactive power and voltage.This paper firstly builds a Volt/Var coordination model of 220 k V plant-grid,and on this basis,this paper makes thorough theoretical analysis of the influence on plants and substations' Volt/Var control to the grid.In addition,this paper selects the plant-grid voltage difference and substations' gateway reactive power as the indices of plant-grid coordination optimizing control,and proposes a multi-target optimization analysis method under two-dimensional control variable in order to provide theoretical support for plant-grid coordination Volt/Var control.On the aspect of reactive power control,based on the principle of reactive power hierarchical balance,an Area Reactive Power Sharing Method(ARPSM)is proposed for a differential setting on gateway reactive power control range of substations in loop networks without power plants.By iteratively sharing reactive power surplus produced by transmission lines in different load levels,this method firstly achieves the gateway reactive power control critical value under condition of optimizing control.Based on the premise that voltage is qualified in entire network,ARPSM secondly revises the gateway reactive power range's boundary,and finally works out the gateway reactive power differential control range adapting to different load levels.This method provides a technical support for the optimizing distribution of reactive power flow by substations in loop networks.On the aspect of plant-grid coordination,this paper combines the coordination optimizing indices and ARPSM,and come up with an IARPSM to achieve the double optimizing loss reduction in the whole network.Considering of plants' reactive power regulation ability,this method firstly formulates the substations' gateway reactive power control interval.Combining with the plant-grid optimal voltage difference under different active power output of plants,this method secondly improves the plants' reactive power output by adjust the voltage of high voltage bus in plants.Finally,this method works out the differential control ranges of voltage of high voltage bus in plants and gateway reactive power in substations,which can adapt to different operation modes.The simulation results show that this method can effectively keep the operation states close to the optimal states,and it has a significant effect on reducing power loss in different load levels and different plants' active power outputs.Meanwhile,this method effenciently ensures the voltage stability of power plants and substations.The proposed method doesn't involve real-time calculation process of reactive power optimization by AVC control master sations,but also can adapt to different operation conditions in power grids,so it has important application value on reactive power control and planning of power grids.