Research On Optimal Control Of Reactive Power And Voltage In Active Distribution Network

The exhaustion of traditional fossil fuels and their pollution to the environment have promoted the development of clean energy.Clean energy,represented by wind and solar,has been connected to the distribution network in the form of distributed generation.The grid structure has undergone great changes and the operational control of the grid has had a huge impact.In the active distribution network,the access of distributed generation changes the flow from unidirectional to bidirectional,and the uncertainty of output power generated by wind power generation,photovoltaic power generation and the like cause voltage fluctuations,which brings difficulties to the optimization and control of voltage.The optimal control of reactive power and voltage is an important means to ensure the safety,stability and economical operation of the power system.It is an important part of the active distribution management system.Therefore,it is of great significance to study the optimal control of reactive power and voltage in the active distribution network.To control the distribution network,first,we must have a control method.This paper describes in detail the methods of controlling the reactive power and voltage in the active distribution network and the control mechanisms of various methods.On the distributed generation side,the grid-connected structures of wind power generation,photovoltaic power generation,and micro-turbines are introduced,and how they achieve voltage regulation through power exchange with the power grid is analyzed;On the grid side,on-load tap-changers and reactive power compensation devices such as traditional shunt capacitors and static var compensators were introduced;On the users side,the two types of demand response methods based on incentive-based demand response and price-based demand response are described,illustrating how the users side actively participates in voltage regulation through demand response.In order to reduce the influence of the uncertainty in the active distribution network on the voltage,aware the voltage situation of the voltage timely and accurately,and achieve the active control,this paper introduces the situation awareness into the voltage control of the active distribution network and proposes a voltage situational awareness methods based on the grey Incidence analysis.The wind speed,light intensity,and load that are closely related to the voltage are collected as factor sets,and the relationship between each situation is mined with the idea of gray Incidence to sense the voltage situation and its future trends.In order to improve the perception effect,the degree of grey incidence is improved under the premise of satisfying the degree of gray incidence,then the algorithm is optimized.The simulation results of the IEEE 33-node and PG&E 69-node power distribution system show that the proposed method can aware the voltage situation and its future trend,evaluating the voltage situation through the voltage qualification rate,then guide the voltage control.When voltage limit violation happens,the signal is sent out,and then the system needs to control voltage and reactive power.In an active distribution network,distributed generation need to actively participate in rather than passively accessing in grid as in traditional distribution networks.Users-side resources also should participate in grid operation control through demand response.Therefore,in order to make full use of the resources in the power grid and make the control of reactive power and voltage more flexible and more reliable,this paper proposes a reactive power and voltage optimization control method based on the source-grid-load interaction in active distribution networks.Three parties cooperate with each other and participate in the optimal control of reactive power and voltage actively.Considering safety and economy,power loss and system voltage offset are taken as objective functions,and state variables and control variables are used as constraints to construct a multi-objective optimization control model.The model is solved using improved multi-objective particle swarm optimization.The simulation results of the IEEE 33-node and PG&E 69-node power distribution system show that the proposed method can achieve a very good control effect.