| Under the guidance of the restructuring of energy consumption and the strategic policy of achieving "carbon peaking and carbon neutrality",the construction of new power system with new energy as the main body is implemented deeply.There is a building large-scale crossregional interconnected power grid in China,which is composed of wind power and photovoltaic resource sending-end power grids in the western and northwestern regions and power grids in the eastern load-intensive areas through long-distance UHV AC and UHV DC transmission line.With the rapid growth of installed capacity of new energy power generation,large-scale photovoltaic and wind power integration,its output uncertainty is high and the controllability of energy output under multi-dimensional time scale is weak,which has an increasingly complex impact on the transient energy balance characteristics and transient stability of new energy high proportion sending system.At present,the development of new energy is facing the following three problems.First,the total installed capacity of new energy is far beyond the load,and is limited by the characteristics of conventional power sources and grid structure,and the problem of new energy consumption is prominent.Second,the connection of large-scale new energy power stations leads to the reduction of conventional power sources in the system,the reduction of system inertia,frequency response characteristics and voltage response characteristics,and the security risk of power grid operation increases significantly.Third,the new energy power station has no energy storage link,which is a source of disturbance to the power grid and has no ability to adjust.Therefore,the safe and stable operation of large-scale new energy connected to the power grid urgently needs to seek new means to assist traditional units to improve the overall regulation capacity of the power grid.This paper firstly studies the modeling and operation optimization method of battery energy storage system and new energy system,so as to realize the coordinated optimization among multiple objectives such as the proportion of new energy energy supply in the interconnected system,the safety and stability of the sending end system,and the operation economy.The transient stability mechanism and discriminant model of the new energy sending-end system can accurately characterize the transient energy characteristics of the sending-end system at the transient fault port and the propagation mechanism of this energy in the sending-end network.The transient stability control method of the new energy sending-end system is established,and the transient energy control and voltage and frequency fast recovery control methods of the sending-end system with battery energy storage are established;finally,based on the transient energy control requirements of the sending-end system,the new energy sending-end system is studied and considered The energy storage optimization configuration method for transient stability improvement realizes the improvement of the transient stability level of the sendingend system in the interconnected large-scale system based on energy storage coordination.The main research contents are as follows:Study on modeling and operation optimization of battery energy storage system and new energy system.With wind power and photovoltaic power as the main new energy sources,the dynamic energy input and output models of new energy sources,traditional synchronous power sources,load and battery energy storage system in the weak sending-end power grid with new energy sources as the main body are studied.On this basis,the dynamic power balance model of interconnected system composed of new energy sending-end power grid,UHV transmission channel and receiving system is studied.The dynamic optimization model and solution algorithm of dynamic power flow optimization for new energy sending end system are studied.The dynamic optimal unit combination of the sending end system under the premise of maximizing the delivery of new energy is calculated,and the coordinated optimization between multi-objectives such as the proportion of new energy supply in the interconnected system,the safety and stability of the sending end system and the operation economy is realized.Study on transient stability mechanism and discriminant model of new energy sending-end system.The high proportion of new energy transmission-end power system is the research object of this paper.Based on the energy balance dynamic model of the new energy transmission-end system and the operation mode optimization model under the target of maximum energy transmission,the dynamic model of the transient energy characteristics of the traditional synchronous power supply,the virtual synchronous power supply and the DC side of the battery energy storage are studied,as well as the energy dynamic characteristics model of the load in the transient process.And the Lyapunov discriminant model for the transient stability of the new energy sending-end system based on the energy dynamic characteristic characterization equation of each component is established.On this basis,under the study of the port energy accumulation and the propagation mechanism model of port energy in the sending-end system when a transient fault occurs in the interconnected system,the grid dynamic division model of the sending-end system is established.Then,based on the energy propagation characteristics in the sending-end network,the fast identification method for weak regions of energy balance in sending-end network is studied with dynamic grid model.Study on transient stability control method of new energy sending end system based on energy storage coordination.Based on the transient stability discrimination model of the new energy sending-end system and the identification model of the weak area of the sending-end network energy balance in the process of transient energy propagation,considering the relationship between battery energy storage and the energy characteristics of various power sources such as thermal power units,PV and wind power generation systems,the multi-objective dynamic coordination control strategy for the rapid suppression of imbalance between the total energy input and energy consumption of the sending-end system is established.The nonlinear multi-objective control method of the voltage and system frequency oscillation process in each local area of the sending-end system under the transient port energy shock is further studied.The method can realize the control of energy balance and voltage and frequency characteristics of the sending-end system during the transient fault process.Study on optimization of battery storage system for improving of transient stability of new energy sending end system.The dynamic robust optimal control model and method for the transient energy and voltage and frequency of the sending-end system coordinated by battery energy storage are studied in this paper.Under the requirements of battery energy storage’s participation in the transient control strategy of the sending-end system and the corresponding system transient stable state conditions of the system,the paper studies the energy characteristics and operating state parameter uncertainty set models of wind power and photovoltaic power fluctuation uncertainty in the system steady-state operation and transient process of the new energy sending-end system.And considering multi-dimensional uncertainty and transient stability constraints,the dynamic optimization model and method of battery energy storage system planning are established. |
PDF Full Text Request