Study On Dynamic Power Flow And Interval Power Flow Calculation Of Distributed Generation

With the development of distributed generation technology,the permeability of wind power and photovoltaic power generation is increasing,but influenced by climate conditions,the power generation power has intermittent characteristics.In order to make the power grid containing wind power and photovoltaic power stable operation,it is necessary to carry out the stability analysis.The calculation of power flow is the basis of the analysis and control of the steady state operation of the power system.Considering the uncertainty of the distributed generation access to the power grid,this paper mainly studies the dynamic power flow calculation of traditional power system,the dynamic power flow calculation of power system with power generation participating in primary frequency regulation,the interval flow calculation of the intermittent distributed power system and the microgrid interval power flow calculation based on the affine Taylor interval expansion function.The research results have some guiding significance for dispatching optimization,operation stability and control protection of distributed generation network system.The main research work of this paper is as follows:(1)The dynamic power flow calculation of traditional power system is carried out.The static frequency characteristic of generator and load and the principle of primary frequency modulation of power system are analyzed,and the dynamic flow model is established.Traditional Newton-Laphson method and improved Euler method are used to solve them.It is proved by simulation that the dynamic power flow calculation takes into account the primary frequency modulation characteristics of generator and load,which is more consistent with the actual power grid operation.(2)A dynamic load flow calculation method for wind power participating in primary frequency regulation is proposed.For the variable speed wind turbine with the coordinated control of overspeed and propeller,the primary frequency modulation characteristic is established.The method of unbalanced power segmentation is proposed in the frequency calculation,and the first order three step RK method is used to solve the system frequency differential equation.4 new type of node types are proposed in the conventional power flow calculation,and the traditional Newton-Laphson method solution is used.The correctness and effectiveness of the proposed method are proved by examples.The results of dynamic power flow calculation can provide a basis for the analysis of wind power and the design of control system.(3)Interval power flow calculation based on Krawczyk interval operator for intermittent distributed power system is carried out.Based on the basic operation rules of interval numbers and affine numbers,the output model of wind power and photovoltaic power generation and the specific interval power flow calculation method are established.The Krawczyk interval algorithm fully shows its role in interval power flow calculation,and the results of interval power flow can provide reference for system stability control and dispatch.(4)An interval power flow calculation method for microgrid based on affine Taylor interval expansion function is proposed.Aiming at different operation modes of master slave control microgrid,the affine Taylor interval expansion function model is established by combining interval numbers and affine numbers.On the basis of the dynamic dynamic interval of the active power output of the intermittent DG device,the affine interval flow model of the master and slave control microgrid is established,and the interval flow algorithm based on the affine Taylor interval expansion function is proposed to calculate the dynamic interval flow.This method can avoid interval iteration and decouple the operation between the region and the iterative operation,and can reduce the area.The amount of inter operation and the improvement of convergence.Finally,a simulation example is given to illustrate the correctness and effectiveness of the proposed method.