Research On Optimal Operation Of Active Distribution Network Considering Network Loss And Power Balance

The increasing demand for electricity is an important manifestation of the improvement of residents' living standards and the development of the regional economy,and the development of DG is an effective way to solve power shortages in the current distribution network.As the main component of the active distribution network,DG has the characteristics of randomness and anti-peak regulation.Therefore,large-scale DG access will bring challenges to the voltage stability and power balance of the power system.In order to improve the economy and reliability of distribution network operation,DG grid-connected technology has attracted the attention of scholars at home and abroad.However,most studies are based on energy storage technology to achieve voltage fluctuations and power balance,resulting in a decline in economy.Therefore,in order to solve the above problems,this paper establishes a DG location and capacity model to realize the optimal network loss access of DG,and based on the active and reactive power control technology of electric spring(ES),the power balance and reliable operation of the active distribution network are realized.The main contents are as follows:First of all,research on the location and capacity method of DG.Considering the timing of DG output and load power,a mathematical model for DG site selection and capacity determination is established.Taking the minimum network loss as the objective function,the particle swarm algorithm is used to solve the problem under constraint conditions.The simulation results of the numerical example verify that the consideration of timing can further improve the method of DG site selection and capacity determination.Secondly,based on the realization of DG optimal network loss access,the active power and reactive power models of a single electric spring are studied.Study ES active/reactive power control method based on ES power control model,establish active power control unit(AP-CU)and reactive power control unit(RP-CU)respectively,and then validity of power control is verified in the established simulation system.Then,the active power dispatching strategy of active distribution network is researched.According to the principle of AP-CU,a virtual power dispatching unit(VPDU)based on ES and fixed-frequency air conditioners is built,and a hierarchical power dispatch strategy is proposed.The dispatching layer formulates a day-ahead dispatch plan based on the objective function and constraint conditions;the load aggregator layer integrates information to conduct day-ahead bidding and allocates power adjustment instructions;the air-conditioning layer responds to power allocation.The simulation results of a calculation example verify the effectiveness of the active power scheduling strategy.Finally,the reactive power compensation strategy of active distribution network is studied.A hierarchical reactive power coordinated control strategy based on RP-CU and distributed static synchronous compensator(DSTATCOM),combined with centralized and distributed reactive power compensation,is proposed to stabilize the voltage of entire line.The upper module takes multi-objective comprehensive optimization as the goal,and uses dynamic adaptive particle swarm algorithm to study the optimal scheme of voltage adjustment;the lower compensation device responds to reactive power commands.The simulation results verify the effectiveness of the cooperative control strategy.