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The advantages of fast charging speed and high efficiency of DC charging piles make the connection and cutting of electric vehicle (EV) loads relatively frequent. However, as a DC system, DC charging pile has the characteristics of low inertia and weak damping. In order to reduce the impact of EV load connection and cutting on the DC side voltage disturbance, a DC charging pile control method based on improved virtual inertia (VI) control is proposed. This paper firstly introduces VI control by analogy with virtual synchronous machines (VSM) technology. Secondly, the VI control is improved by using command filter backstepping integral sliding mode (CFBISM) control, in which the integral sliding mode (ISM) control is used to optimize the VI control to enhance the robustness of the system, and the command filter backstepping control is used to reconfigure the key parameters to avoid the computational inflation of the controller, while the ISM control is used to improve the current inner loop to further enhance the control effect. The stability of the proposed control strategy is then demonstrated by the Lyapunov stability criterion. Finally, through comparative simulation, it is verified that the DC-side voltage fluctuation can be limited within 2 V, the dynamic response speed is improved by about 0.1 s, and the perturbation of the key parameters in the steady state is limited to about 1 V, thus the superiority of the fast response speed and good robustness of the control proposed in this paper are verified by simulation.

Aiming at the voltage fluctuation problem caused by indirectness and uncertainty in new energy power generation system, the backstepping control strategy is firstly applied in electric spring (ES) system, and an ES backstepping control strategy with command filtering is proposed. According to the mathematical model of ES, the controller is designed by backstepping method and command filter is added to solve the computational inflation problem in ES backstepping control. Meanwhile, the error compensation signal is designed, and the stability of the system is verified by the Lyapunov stability theory. The effect of ES on critical load (CL) voltage stabilization is simulated when the grid-side voltage of the new energy power generation system fluctuates, and the sensitivity analysis of different system parameters to the control strategy is discussed in this paper. Compared with traditional proportional integral (PI) control, the dynamic response speed of CL voltage is improved by 0.07 s, while the CL voltage distortion rate is reduced by 31%. In parameter sensitivity analysis, the maximum deviation rate of CL voltage is 0.318%. Meanwhile, the maximum voltage amplitude fluctuation range that it can withstand is increased by 52.9 V. It is verified that the control strategy proposed in this paper has the advantages of fast response, low harmonic content and strong anti-interference ability.

As a new power electronic equipment, energy routers (ERs) can realize the flexible distribution of electric energy in power systems. It is of great significance to analyze the influence of energy routers on the system and study the power flow calculation methods of AC-DC hybrid distribution networks with ERs as the distribution hub. In this paper, the steady state power flow model of ERs is established based on the improved alternating iteration method, and the droop control strategy is adopted for the DC port of the ERs. Combined with the traditional decoupling method, an AC-DC decoupling iterative power flow calculation method suitable for the power distribution network containing ERs is proposed. An IEEE 14-node and IEEE 69-node system with multiple ERs are used as examples to verify the correctness and convergence of the proposed method. In order to analyze the influence of ERs on the system operation, the simulation calculation of IEEE 69-node test system in different scenarios proves that ERs can support the node voltage in the system and reduce the system operation loss.

Model predictive control is highly dependent on accurate models and the parameters of electric motor drives. Multiphase permanent magnet synchronous motors (PMSMs) contain nonlinear parameters and mutual cross-coupling dynamics, resulting in challenges in modeling and parameter acquisition. To lessen the parameter dependence of current predictions, a model-free predictive current control (MFPCC) strategy based on an ultra-local model and motor outputs is proposed for five-phase PMSM drives. The ultra-local model is constructed according to the differential equation of current. The inherent relation between the parameters in the predictive current model and the ultra-local model is analyzed in detail. The unknowns of the ultra-local model are estimated using the motor current and voltage at different time instants without requiring motor parameters or observers. Moreover, space vector modulation technology is employed to minimize the voltage tracking error. Finally, simulations and experiments are conducted to verify the effectiveness of the MFPCC with space vector modulation. The results confirm that the proposed method can effectively eliminate the impact of motor parameters and improve steady-state performance. Moreover, this control strategy demonstrates good robustness against load variations. [ABSTRACT FROM AUTHOR]