Research On Dynamic Equivalent Method Of Power System Based On Wide Area Measurement Data

With the continuous expansion of China’s power grid,the large-scale integration of renewable energy,the development of AC-DC hybrid transmission and regional interconnection operation,higher requirements for simulation analysis and operation control in the power system are required.In order to accurately simulate the post-fault dynamic characteristics and response of the AC-DC system in the safety assessment,and to reduce the simulation scale and calculation,the systen needs to be simplified reasonably.Power system dynamic equivalence is an important means to improve the efficiency of power system dynamic stability analysis and time-domain simulation.In the electricity market,it is difficult to construct the equivalent system based on coherent equivalence method and mode equivalence method of the detailed model in the original system.In view of this,a wide area measurement data-driven dynamic equivalence based on the estimation equivalence method is proposed in this paper,for constructing a large-scale AC-DC hybrid Power system dynamic equivalence model.The main research are as follows:First of all,considering the impact of electrical distance,coherent relationship of generators and geographic location of regional grid on equivalent accuracy,the range of the study area and the external area is determined.Furthermore,based on steady state electrical measurement information of the regional boundary,the static equivalent parameters are identified.Then,the equivalent generator in the external area is supposed to classic model.Taking the minimum square error of the bus voltage at the boundary of the study area before and after equivalence as the objective function,the transient reactance of the equivalent generator is identified by taking the boundary bus voltage and tie line complex power of the study area as input.Further,the internal voltage and rotor angle state of equivalent generators are calculated based on the relationship between the generator electrical parameters.The objective function to minimum the error between the equivalent generator active power and tie-lines of original system active power is employed to identify the inertia 7} and damping D of the equivalent generator by Least-Square method.On the basis of the above,the root mean square error(RMSE)and curve fitting degree are used as indicators to quantitatively analysis the consistency of dynamic simulation results in the study area at the same fault in this paper.The distribution of oscillation mode before and after equivalence based on prony method is analyzed at the same fault.Finally,the proposed method is verified by the modified IEEE 68-bus test system and the four-terminal VSC-based DC grid project in Zhangbei.The simulation comparison between the equivalent system and the original system verifies the effectiveness,accuracy of the proposed method and feasibility of application in actual systems.