Research On Robust Operational Optimization Technologuy Of Active Distribution Network

With the development of the energy and environmental crisis,grid-connected renewable energy sources such as wind power and photovoltaics have gradually become the focus of current research.The distribution system with high permeability of renewable energy is faced with the features like high operational uncertainty and complex and variable operating conditions.In order to meet the challenges brought about by large-scale renewable energy grid integration,active distribution network technology has emerged.That is,under the overall planning of intelligent communication and measurement equipment,the active management and coordinated control of distributed generation,battery energy storage system,demand response,and reactive power regulation equipment in the distribution network are realized.The optimization of system operation as the core part of the active power distribution network to implement overall situation energy active control is a key technical method for active distribution network research.Therefore,how to optimize the operation of the system considering the randomness of renewable energy output is particularly important.From the perspective of robust optimization of the system,under the active distribution network technology framework,the two-stage adaptive robust optimization algorithm of active distribution network,the adaptive robust optimization algorithm improvement based on approximated value function and the robust optimization method of active distribution network participating in the market are studied.The main tasks include:(1)The research background and current situation of engineering application of active distribution network are introduced.The key technologies of active distribution network research are summarized at the present stage.The research status of active distribution network in the field of system optimal operation are analyzed and compared.(2)Aiming at the the different operating characteristics for discrete and continuous variables in active distribution networks,a two-stage adaptive robust optimization method for active distribution networks is proposed.With the goal of minimizing network losses,an active-reactive joint optimization model was established that comprehensively considered continuous and discrete controllable devices such as photovoltaic inverters,battery energy storage systems,static reactive power compensation devices,switchable capacitor banks,and on-load tap-changers.In order to make full use of the real-time energy balance capability of battery energy storage system in high-permeability and strong-random environment of renewable energy,it is used as a real-time adjustable device to make the second-stage decision-making correction.In order to ensure the feasibility of the adaptive robust optimization method,the second-order cone relaxation method is adopted in the distribution network power flow model,and the corresponding algorithm is improved.(3)Aiming at the problem of low efficiency of model solving caused by the constraint of many discrete variables and time coupling constraints in the active distribution network with strong randomness,on the basis of an adaptive robust optimization model for active distribution networks,the optimization objectives and modelling of controllable devices continue to be refined.And an adaptive robust optimization model for the time decoupling active distribution network is constructed by using the idea of approximate function in approximate dynamic programming.Approximate value function is obtained by successive projection approximation algorithm.Robust recursive solution of the model is implemented by using the column and constraint generation algorithm.(4)Explored the problem of robust optimal operation of the active distribution network as an electricity supplier in the electricity market environment,and proposed a day-ahead energy and reserve joint robust optimization model considering the reactive voltage adjustment capability of the distribution network and the load demand response.Firstly,the linear flow control of the original problem is linearized by the linearized branch power flow method.Then the affine adaptive robust optimization is used to construct the affine relationship between the fluctuating variables and the controllable variables,so as to improve the robustness of the system operation,reduce the operating cost the operational risk.Finally,the influence of demand-side response and reactive voltage regulators on the optimization results is analyzed.