Studies On Generalized Synthesis Load Modeling For Intelligent Dispatching

Intelligent dispatching depends on real-time power grid simulation,and the load model is one of the key factors that affect the accuracy of simulation results.Therefore,load modeling has been widely concerned.It is very difficulit to establish a unified general load model due to load's time-varying nature,regionalism as well as diversity and so on.Under the background of intelligent dispatching,real-time power grid simulation has higher requires to load modeling: on the one hand,load modeling should solve the time-varying problem of load to adapt to the dispatching simulation under different operation modes;on the other hand,load modeling should be wide area oriented for modeling all substations involved in power grid simulation.Based on the application scene of intelligent dispatching simulation,this paper studies the comprehensive load modeling of distribution network with generalized load,in order to solve the key model structure problem in the field of load modeling;m aking full use of the rich load characteristic data provided by power grid automation system,the real-time load modeling platform is developed to provide real-time and wide area load model parameters for intelligent dispatching simulation.The main contents of this paper are as following:(1)Considering that the present composite mechanism load mo dels have imperfections in model structures,an improved composite load model structure is proposed.According to the actual situation that load always locates in the middle-and low-voltage area of distribution network,the proposed load model dis tinguishes the middle-and low-voltage network from high-voltage in distribution network,and models them,separately: the middle-and low-voltage network,including load,represented with classical load model(CLM),and the high-voltage netork is modeled using an impedance in series with a Pi type circuit.The Pi type circuit bases on the Pi type equivalent principle.The voltage ratio of Pi type circuit is set with the steady state voltage value of substation high-voltage bus,which can reflect the result of voltage regulation in distribution network.The proposed model has better performance and parameter stability under different voltage levels through comparing the existing composite load models.(2)Aiming at the widespread existent photovoltaic power generation system in the future smart distribution network,a generalizd load model for distribution network with photovoltaic power generation system is put forward.A photovoltaic array simulation is established,and the main links of photovoltaic grid connected simulation system are introduced;based on the photovoltaic grid connected simulation system,dynamic characteristics of photovoltaic power grid connected generation system are analyzed,and then a two-order dynamic model for the photovoltaic power generation system is proposed and some simulation vericicaitons are carried out.A generalized composite load model for distribution network with the photovoltaic power generation system is put forward using the proposed two-order dynamic model.Based on a simple distribution network simulation system with photovoltaic power generation system,the effectiveness of the proposed generalized composite load model is verified.(3)In view of the widely used the battery energy storage system(BESS)in future smart distribution network,a dynamic BESS model suitable for load modeling is put forward.A general energy storage battery model based on equivalent circuit method is established;the dynamic characteristics of grid connected BESS are analyzed through its simulation system,and then,a dynamic model suitable for load modeling,which is not limited to load modeling,is put forward,and its improved model is also presented.Simulation results show that the proposed dynamic model has well description performance and can be used to describe the dynamic behavior of BESS under charging and discharging conditions.The effectiveness of the proposed generalized composite load model is tested through modeling and analysis of three scenarios with different access capacity under the discharging condition,and is further verified under the charging condition.(4)Load characteristic of distribution network with BESS is studied,and it is pointed out that the load modeling of distribution network with BESS should consider the necessity of dynamic characteristics of BESS.A generalized composite load model for distribution network with BESS is put forward using the proposed BESS dynamic model.The effectiveness of the proposed generalized composite load model is tested through modeling and analysis of three scenarios with different access capacity under the discharging condition,and is further verified under the charging condition.(5)In view of the real-time and wide area requirements of intelligent dispatching simulation for load modeling,the intelligent dispatching oriented real-time load modeling platform is developed using the modeling data source from power grid automation system.From the point of view of servicing intelligent dispatching simulation,the key theoretical and technical problems ans design principles involved tin the development of real-time load modeling platform are expounded.On this basis,the overall framework of the platform development is put forward in combination with the requirements of the dispatching simulation for the platform.By connecting the developed real-time modeling platform to the data platform in an Electirc Power Co.,Ltd.,the modeling results show that the developed real-time load modeling platform can meet the requirements of the intelligent dispatching simulation for the load model.