Wang Kai

Bio: Wang Kai is an academic researcher from Huazhong University of Science and Technology. The author has contributed to research in topics: System equivalence & Hybrid power. The author has an hindex of 1, co-authored 1 publications receiving 13 citations.

Study of Coherency-based Dynamic Equivalent Method for Power System with HVDC

Abstract: In order to reduce the calculation amount of numerical simulation in transient analysis for large-scale power system, the network can be simplified by dynamic equivalence. This paper presents the coherency-based equivalent technique for power system with HVDC. Both frequency-domain method and weighting method are comprehensively used in parameter aggregation section in this paper. The adaptability of ac system equivalence to dc system is concerned, and the accuracy of dynamic equivalence of ac system is estimated using dc system disturbance. In numerical simulator PSASP, a dynamic equivalence of EPRI 8-machine 36-bus ac/dc hybrid power system can be derived, in which the specific model of HVDC system is considered. The comparisons of steady-state and dynamic response of original and equivalent system show that the dynamic equivalent model is feasible and available.

Precise equivalent model of small hydro generator cluster and its parameter identification using improved Grey Wolf optimiser

Abstract: With the total installed capacity of small hydro generator cluster (SHGC) continues to grow rapidly, the effect of SHGC will have affected to the security and stability of the main network in China, especially to power oscillations of passageway of ultra-high-voltage AC and DC. Thus, a precise equivalent model of SHGC is proposed in this study. In the proposed model, the fifth-order model of generator is adopted as the equivalent generator model, the excitation system is simplified into proportional feedback control model and exponential load model is used as equivalent load model. In addition, Grey Wolf optimiser with chaotic local search is designed to identify the parameters of the equivalent model. Finally, the proposed equivalent technique is applied in one simulation experiment and one practical experiment. The experimental results demonstrate that the validity and accuracy of the proposed equivalent model and identification method in solving dynamic equivalent of SHGC in engineering practice.

Dynamic Equivalents by Modal Decomposition of Tie-Line Active Power Flows

Abstract: This paper addresses the power system model order reduction proposing an optimal formulation for identifying electromechanical modes present in active power flows. The reduced power system preserves the dynamic and physical characteristics of the studied system. The modal identification is achieved by the digital Taylor–Fourier transform, which decomposes an oscillating signal into monocomponents. Then, these ones are embedded into an objective function with the purpose of estimating the equivalent generators’ parameters. Results demonstrate a reduction in the computational burden and the computing time associated with transient stability studies for the preserved system, retaining its steady-state and dynamic conditions.

Residualisation-based model order reduction in power networks with penetration of photovoltaic resources

Abstract: With the accelerating advances in renewable energy technologies and growing penetration of these sources as distributed generation units in the power systems and utility networks, designing controllers has become more complicated. Model order reduction is a proper way to ease this process. In this study, an order reduction procedure based on the residualisation method is designed to reduce the order of the system. The major advantage of the residualisation method is its capability in preserving steady-state gain of the system. This characteristic increases the accuracy of the approximated system, which is demanded in designing the controller. The model of a slightly modified IEEE 14 bus test system with penetration of photovoltaic resources is implemented and reduced through the proposed procedure. Simulation results show the better performance of the residualisation-based method in the steady state compared with three other widely used methods.