This paper presents a new model predictive direct power control (MP-DPC) to overcome the drawbacks of model predictive control (MPC) for single phase three-level rectifiers in the railway traction drive system, including huge online calculation, poor power control precision at the low switching frequency and variable switching frequency. To do so, an exact analytical solution of instantaneous power estimation is adopted to predict active and reactive powers in next duty cycle updating interval for achieving the deadbeat control and reducing the predictive error at the low switching frequency (below 1 kHz). The optimal d -axis and q -axis components of input voltage within next duty cycle updating interval of the adopted rectifier in rotating coordinate system are directly calculated by minimizing the cost function. And the optimal drive pulses are generated by pulse width modulation stage in the proposed MP-DPC, other than evaluating cost function for each voltage vector in traditional MP-DPC. Finally, the influence of inductance mismatch on control system is analyzed, and an inductance estimation method is shown to improve the control precision. An experimental comparison with other five different DPC schemes has verified the effectiveness of the proposed MP-DPC scheme.

Online parameter identification is vital for boosting the accuracy of the battery equivalent circuit model (ECM) under dynamic profiles. However, traditional recursive least squares (RLS) method easily decays with the noise corruption from sensors or insufficient exciting signal in reality, which further limits the performance of ECM in battery modeling and states estimation. This article thus proposes a reliable online parameter identification method for battery ECM, which utilizes a well-designed information appraisal procedure based on the Fisher-information-based Cramer–Rao lower bound (CRLB). Without increasing much computing complexity, a comprehensive appraisal indicator, derived recursively from CRLB, enables a new mechanism for online parameter updating. Simulation and experimental results prove the validity of the proposed method under different driving cycles, temperatures, and aging conditions. The results show that the identification accuracy of the proposed method has been significantly improved comparing with a typical RLS and a multiple adaptive forgetting factors RLS method.

In order to enable the permanent magnet synchronous generator (PMSG)-based wind turbine (WT) to capture more wind energy while providing fast frequency supports effectively during disturbances, this paper proposes a time-sharing frequency coordinated control (TFCC) strategy. Firstly, a rotor virtual inertia control and a DC-link virtual inertia control are presented, and a new adaptive frequency droop control considering frequency deviation is proposed. Secondly, a novel TFCC strategy, which uses the frequency dead-band to coordinate the frequency regulation priority of above three controls, is proposed. With the proposed strategy, the electrostatic energy stored in the DC capacitor is always first utilized for frequency support, while the rotor rotational kinetic energy is only applied when the DC capacitor energy is used up. Finally, the control performance is studied in PSCAD/EMTDC, whose results indicate that the TFCC has better performance in terms of wind energy harvesting and system stability as compared to traditional coordinated control and cascading control, respectively.

High proportion of wind energy in modern power system requires wind turbines (WTs) to provide frequency regulation services. In this context, this paper proposes a comprehensive coordinated control strategy of permanent magnet synchronous generator (PMSG)-based WT for providing inertial response and primary control. Firstly, a DC-link inertia control is proposed for providing virtual inertia by using the electrostatic energy stored in the DC capacitor, and the key parameters that affect the virtual inertia provided by this control are discussed in detail. Moreover, in order to provide more virtual inertia, a virtual capacitor control (VCC) strategy is proposed. With the VCC strategy, the rotor-side converter (RSC) can provide a virtual capacitance much larger than the actual DC capacitance and supply fast and transient extra power support by using the WT’s rotor kinetic energy, in a similar way with the synchronous generator (SG) inertial response. A power-frequency droop control is adopted to allow WT to provide primary control service by using the WT’s rotor kinetic energy. Furthermore, the virtual inertia constant of the proposed strategy is analytically derived. Finally, the simulation results in PSCAD/EMTDC are presented to verify the effectiveness of the proposed control strategy.

SCR-based Solid-state DC circuit breaker (SCR-DCCB) topologies have been widely studied for replacing traditional expensive IGBT-based DCCB. Yet, the existing SCR-DCCB cannot be actively turned-off since SCR is a half-controlled device. In this letter, an active Z-source DCCB (AZ-DCCB) is proposed by the combination of IGBT and SCR. The proposed AZ-DCCB has advantages of simple and compact topology, economical design, low conduction losses, active and bidirectional current breaking capacity. The operation process of the proposed AZ-DCCB is discussed in detail, and the designing principle of circuit parameters is also presented. Experimental results verified the effectiveness of the proposed AZ-DCCB.

Replacing expensive IGBT with thyristor to design dc circuit breaker (dcCB) is attracting attention recently due to its advantages in terms of low investment and low conduction loss. However, due to the half-controlled characteristic of thyristor, the existing thyristor-based dcCBs (T-CBs) cannot be actively turned off. As a result, the opening process is not fully controllable and reliable. In this letter, a simple active T-CB (AT-CB) topology is proposed. The proposed AT-CB can interrupt both fault current and operation current actively, and the current breaking process is fast, reliable, and fully controllable. Moreover, the proposed AT-CB can be improved to be bidirectional without increasing the conduction loss, and the topology remains simple. Parameters design principle and operation process of AT-CB are presented. Scaled-down experiment verified the effectiveness of the proposed solution.