Research On Voltage Hierarchical Control Method Of Active Distribution Network

The rapid development of national economy and power industry,especially the rapid development of active distribution network technology,makes the voltage control work face many challenges at present.The difficulty lies in the uncertainties of the output of several distributed generators and the deviation between the actual load and the predicted value in the distribution system.On the basis of summarizing the existing research results of active distribution network voltage control,this paper establishes a hierarchical voltage control model,which is divided into two parts.The game tree method is used to solve the game optimization model for system-level voltage control,and the device level voltage control is divided into two stages.The multi-objective optimization model and the adjustable droop curve control model are established respectively,and the Latin hypercube optimization algorithm is used to solve the problem of many variables in the optimization process.The main research contents are as follows:(1)Based on the theory of hierarchical model of enterprise system integration,this paper proposes a hierarchical voltage optimization system for active distribution network,which realizes the optimal control and management of active distribution network voltage by optimizing the system level before it is finished,and optimizing the equipment level after it is finished in a day.(2)System level voltage adjustment for 24 hours prior to the optimization of the size,the completion of on-load voltage transformer and reactive switchover equipment program.Based on the analysis of the influence of on-load voltage regulating transformer,reactive power switching device,distributed power output and load fluctuation on the voltage control process,a game method is proposed to solve the system level optimization problem of distribution network considering uncertainty.In this method,uncertainty is transformed into a game of "nature" control by virtual participants,and the two sides of the game are composed of the traditional dispatcher and the dispatcher.Through the simulation analysis of IEEE33 bus,the voltage control scheme before the system level is completed to verify the effectiveness of the proposed method.The robustness of the proposed method is analyzed by comparing the scheme without considering the uncertainty and the scheme with different prediction precision.(3)Adjustment of Equipment Level Voltage Optimizes the active and reactive power of distributed power within a day.At the same time,the actual power output and actual load of the distributed power generation are known when the system level is in the process of optimizing.On this basis,the process of equipment level voltage control can be divided into active power and reactive power optimization stage because of the low speed and high cost of active power regulation.Firstly,a multi-objective optimization model with the reference values of active power output and reactive power output as variables and the minimum network loss and voltage deviation is established at the minute scale.Aiming at reactive power of distributed generation,an improved droop curve control optimization method is adopted.The control model of 1 order adjustable droop curve is established with the minimum voltage deviation and the variable of voltage operation parameter.The reactive power output is realized by adjusting the reference value of reactive power output and the parameter of operation voltage in different periods of the distributed power supply.The optimization algorithm based on symmetrical Latin hypercube principle is used to solve the problem of multidimensional variables in the process of voltage control.Through inheriting the system level example setting and voltage regulation scheme,the IEEE33 bus system equipment level voltage regulation strategy is made,and the effectiveness of the proposed method is verified.