This paper investigates the impact of phase-locked loop (PLL) dynamic on the stability of DC-link voltage control (DVC) in voltage source converter (VSC) attached to weak grid. To start with, a small signal model of VSC attached to weak grid in DVC timescale is presented for stability analysis. On the basis, the dynamic characteristics of VSC are analyzed from the perspective of damping and restoring components which can determine the stability. With considering PLL dynamic, it is found that PLL performs as a phase-lag regulation for DVC and generates additional negative damping component in weak grid, thus weakening the stability of VSC. Furthermore, impacts of PLL’s phase-lag characteristics on additional damping and restoring coefficients are evaluated with variation of grid strengths, operating points and PLL bandwidths to reveal the impact mechanism of PLL dynamic on stability of DVC in VSC. Finally, time-domain simulation and StarSim hardware-in-the-loop (HIL) experimental results are conducted to validate the aforesaid stability analysis.

The large amount of harmonic distortion produced by nonlinearity drives may transmit and couple between grid and multiple drives, which changes the stresses of devices as well as the DC-link filters. This paper investigates the lifetime of DC-link capacitors in multiple drives system. Firstly, by decoupling the interactions among grid-connected drives, a simplified equivalent circuit model and its analytical model to obtain the DC-link continuous current in multiple standard and slim drives is proposed, which releases the designers from configuraing the large simulation for multiple drives. Then, applying the lifetime prediction method, the lifetime of DC-link capacitors in multiple drives are investigated, in terms of types of drives, numbers of drives and grid conditions. The results show that the lifetime of the standard drives extend in the multi-drive systems and lifetime of the slim drives decrease in the multi-drive systems, which break the previous mind. Finally, based on the proposed analytical model and lifetime estimation method, the capacitor sizing from reliability aspect for multiple slim drives are given. The outcomes of the lifetime investigation could be a guideline for the design of capacitive DC-link in multi-drive system

In terms of high-current measurement of capacitors, PCB Rogowski coils have attracted much attention because of their small size and easy installation. However, they are vulnerable to electromagnetic interference. In order to improve the immunity of the coil, this paper studies the influence of the structure and parameter changes of the double-layer PCB coil on the measurement accuracy of mutual inductance. By testing the frequency response of four common coil structures, a differential winding coil structure is proposed. Based on the measurement of large capacitance current, the influence of non-electrical parameters of coils on the measurement accuracy of mutual inductance is experimentally verified.

A parallel active power filter (APF) is generally used to suppress dynamic harmonic current and compensate reactive power in the grid. However, parallel APF may have a negative effect on the load current when compensating the nonlinear load of a voltage source type, which may lead to the amplification effect of the load harmonic current. In this paper, the fundamental causes of harmonic current amplification were analyzed by studying the harmonic current amplification effect when a parallel APF compensates a nonlinear load. According to the results of the theoretical derivation, a feasible method to limit this current amplification effect by changing the system structure and the APF’s own control was proposed, and the corresponding design scheme is given. Finally, the correctness of the theoretical derivation of the harmonic current amplification effect and the feasibility of the proposed solution were proven through simulation and experiment.

Being inches from the rapid development of new energy technology, the capacity of high-power power electronic equipment is increasing rapidly, and the requirements for its safe and reliable operation are also rising. As a result, the demand for online temperature monitoring of such equipment is becoming increasingly urgent. RFID temperature measurement technology can be used for real-time monitoring of the temperature of powered operation equipment. However, the operation of high-power electronic equipment generates strong electromagnetic interference, which can seriously affect the normal operation of RFID temperature measurement systems. For applications involving the internal temperature measurement of high-power power electronic equipment, this paper employs an RFID anti-metal temperature tag antenna with a short-circuit cutoff structure. This structure was tested in an excitation switchgear cabinet. During the low-power operation of the cabinet, the temperature tag functioned normally. By combining an RFID antenna model with an electromagnetic interference simulation model of the main circuit of the excitation switchgear cabinet, this paper establishes an electromagnetic interference simulation model for an RFID temperature tag. It analyzes how the tag’s antenna performance parameters change when subjected to interference. Through simulation, the failure mechanism of the RFID temperature tag during the high-power operation of the excitation switchgear cabinet is clarified. The analysis found that there are both conductive electromagnetic interference and radiated electromagnetic interference in the excitation switchgear cabinet, with the conductive electromagnetic interference having a more significant effect. Conductive electromagnetic interference can seriously impact the performance of RFID temperature tags in the excitation switchgear cabinet, significantly degrading their performance. In contrast, the effect of radiated electromagnetic interference on the tags is relatively small. Therefore, this paper employs anti-metal RFID temperature tags and simulates and analyzes their electromagnetic interference characteristics.

With the increasing capacity of wind turbines, key components including the rotor diameter, tower height, and tower radius expand correspondingly. This heightened inertia extends the response time of pitch actuators during rapid wind speed variations occurring above the rated wind speed. Consequently, wind turbines encounter significant output power oscillations and complex structural loading challenges. To address these issues, this paper proposes a novel pitch control strategy combining an effective wind speed estimation with the inverse system method. The developed control system aims to stabilize the power output and rotational speed despite wind speed fluctuations. Central to this approach is the estimation of the aerodynamic rotor torque using an extended Kalman filter (EKF) applied to the drive train model. The estimated torque is then utilized to compute the effective wind speed at the rotor plane via a differential method. Leveraging this wind speed estimate, the inverse system technique transforms the nonlinear wind turbine dynamics into a linearized, decoupled pseudo-linear system. This linearization facilitates the design of a more agile pitch controller. Simulation outcomes demonstrate that the proposed strategy markedly enhances the pitch response speed, diminishes output power oscillations, and alleviates structural loads, notably at the tower base. These improvements bolster operational safety and stability under the above-rated wind speed conditions.