The virtual synchronous generator (VSG) is introduced to address the insufficient inertia and damping in modern power grids. Owing to the stochastic and variable outputs of distributed generation units, power systems are particularly vulnerable to oscillations. In this paper, the nonlinear dependency between inertia and angular velocity is examined, and a radial basis function neural network is adopted within the VSG to emulate this nonlinear behavior. To mitigate system oscillations more effectively, the damping coefficient is dynamically regulated in response to inertia variations, while a constant damping ratio is maintained. Comparisons with alternative control approaches confirm the validity of the proposed technique and demonstrate its favorable control performance.

Aiming at the problems of poor real-time performance and low time-frequency resolution in existing detection algorithms for composite power quality disturbances,a real-time power quality disturbance detection method based on improved adaptive S-transform(IAST)is proposed.A globally adaptive Gaussian window is constructed as the kernel function of the IAST,allowing the effective window length and frequency spectrum to adapt dynamically with the detection frequency.This avoids the need for frequent switching of window parameters to improve time-frequency resolution,thereby reducing algorithm complexity.The window parameters are optimized with the objective of enhancing signal energy concentration,ensuring accurate time-frequency positioning of various types of disturbances.An automatic thresholding method is used to determine the dominant frequency points of the actual disturbance signals,which are then subjected to time-frequency transformation to further improve computational efficiency.Simulation and experimental results show that,compared with existing algorithms for detecting composite power quality disturbances,the proposed method offers superior real-time performance,strong time-frequency resolution,and low computational complexity,making it suitable for accurate real-time detection of complex power quality disturbances.

Aiming at the existing ferromagnetic resonance protection measures have the disadvantage of after-the-fact remediation, this paper analyses the influence factors of ferromagnetic resonance, determines its key influencing factors, and studies its influence law.. Based on ATP-EMTP, a simulation model of electromagnetic voltage transformer(PT) ferromagnetic resonance is constructed, and the influence of system capacitance to ground, PT excitation characteristics and fault point grounding resistance on the ferromagnetic resonance of electromagnetic voltage transformer is studied. Simulation results show that the study analyzes the key influencing factors of ferromagnetic resonance and provides a theoretical basis for the prevention and inhibition of ferromagnetic resonance faults.

The increasing penetration of renewable energy into power systems has intensified transient power quality (PQ) disturbances, demanding efficient detection and classification methods to enable timely operational decisions. This paper introduces a hybrid framework combining an Improved Adaptive S-Transform (IAST) with a Random Forest (RF) classifier to address these challenges. The IAST employs a globally adaptive Gaussian window as its kernel function, which automatically adjusts window length and spectral resolution based on real-time frequency characteristics, thereby enhancing time–frequency localization accuracy while reducing algorithmic complexity. To optimize computational efficiency, window parameters are determined through an energy concentration maximization criterion, enabling rapid extraction of discriminative features from diverse PQ disturbances (e.g., voltage sags and transient interruptions). These features are then fed into an RF classifier, which simultaneously mitigates model variance and bias, achieving robust classification. Experimental results show that the proposed IAST–RF method achieves a classification accuracy of 99.73%, demonstrating its potential for real-time PQ monitoring in modern grids with high renewable energy penetration.

With the access of a high proportion of renewable energy units to the power grid, the equivalent inertia of the power system continues to decrease, and the frequency stability of the system is seriously deteriorated. To this end, this paper proposes a new power system equivalent inertia estimation method based on dynamic time warping (DTW) and convolutional neural network and bi-directional long short-term memory network (CNN-BiLSTM). Firstly, a system equivalent inertia estimation model based on CNN-BiLSTM is established. The model integrates the spatial feature extraction capability of CNN and the temporal feature extraction capability of BiLSTM to improve the accuracy of inertia estimation. In addition, in order to select buses that can characterize the system frequency, a frequency difference index algorithm based on dynamic time warping is proposed. The bus with the minimum frequency difference is taken as the system frequency bus, and the system equivalent inertia is estimated based on the frequency data of the bus. Finally, the effectiveness of the proposed method is verified by building an improved IEEE 39-bus system model. The results show that the proposed method has a high equivalent inertia estimation accuracy.

Coal resources account for 94% of the fossil energy structure in China, while accidents under mines occur frequently throughout the country, seriously threatening the lives of miners. Realizing precise positioning of underground personnel is an important guarantee for safe production of miners and rapid search and rescue work in the event of accidents. This article adopts the bilateral bidirectional ranging (DS-TWR) method to measure the distance between the positioning base station and the positioning label. This method does not require clock synchronization between the positioning base station and the positioning label system, and improves the positioning accuracy by improving the ranging accuracy. Based on the obtained distance measurement information, a position calculation algorithm combining the full centroid algorithm and Taylor algorithm with Kalman filtering is used to estimate the coordinates of the positioning label. The performance of the algorithm is analyzed through static and dynamic experiments, and the positioning accuracy is evaluated through root mean square error.

Accurate fault localization is difficult to achieve by the complex structure of distribution networks, numerous branches and the penetration of a large number of distributed energy sources. In order to solve the problem of accurate single-phase grounding fault localization in distribution networks, a fault localization method is proposed based on EWT-AOE_SD with section optimization equation. The empirical wavelet transform and analytic energy operator of symmetrical differencing (EWT-AOE_SD) are used to calibrate the travelling wave head, and the single-ended ranging equation is used to calculate the fault distance. On the basis of single-ended ranging, the section optimization equation is constructed, solve the equations using the whale swarm optimization algorithm, and the section with the smallest calculated value is the fault section, while the optimal solution of the equation also reflects the fault distance. The method does not require the travelling wave detection device to keep the clock synchronous, eliminating the effect of synchronization error. The simulation results of MATLAB proved that this method has high accuracy.

When a three-phase Vienna rectifier adopts a finite set power predictive control algorithm under voltage imbalance conditions, harmonics will be generated in the AC side current, and the DC output voltage will also fluctuate. Therefore, this article studies the operation law of three-phase Vienna rectifier under three-phase voltage imbalance conditions, and proposes a new power prediction control strategy to eliminate harmonics on the AC side and voltage fluctuations on the DC side. This strategy adopts the second-order generalized integration method to obtain orthogonal voltage signals, and suppresses the second harmonics of the active component and the the reactive component by using different definition methods for instantaneous reactive power. In this situation, the DC bus voltage could be well stabilized, and the current harmonics in AC side could also be seriously reduced Finally, by establishing a simulation model a simulation model on the Matlab/Simulink platform, it was verified that the control strategy can operate stably under three-phase input voltage imbalance.

扩展移相(EPS)控制是双有源桥(DAB)变换器的一种常用控制方式,但现有EPS控制优化存在策略优化目标单一的问题.为此,提出了一种基于EPS控制的回流功率和电流应力综合优化控制策略,优化目标是在保证回流功率最小的前提下优化电流应力,采用有约束极值法求解得出综合最优控制策略,进而设计了EPS综合优化闭环控制器.最后,通过实验对所提控制策略进行了验证.实验结果表明,所提控制策略降低了DAB变换器的回流功率和电流应力,提升了DAB变换器效率.

The AC/DC hybrid power distribution system based on solid-state transformer（SST） is of great significance for large-scale consumption of renewable energy. Reliable control strategy is the key to ensure stable operation of hybrid power distribution system. In this paper, the coordinated operation control strategy of AC/DC hybrid distribution system based on SST is proposed. The control strategy of “source, storage and load” in the subnet can realize the power balance in the subnet independently. The low-voltage level can maintain the low-voltage AC bus voltage and realize the mutual assistance of AC and DC subnets. The isolation level coupling medium-voltage DC bus and l low-voltage DC bus, support the medium-voltage DC bus voltage. Medium-voltage level can construct medium-voltage AC bus voltage, realize mutual support between low-voltage and medium-voltage levels, and adopt voltage-source output form when off-grid and grid-connected, without switching control strategy, and cooperate with pre-synchronization control to realize seamless switching between modes. RTDS simulation results show that the system can adopt a unified control strategy, and achieve power coordination and seamless switching between multiple modes in the AC/DC hybrid distribution system based on SST without communication, which verifies the effectiveness and feasibility of the proposed control strategy.

现有双有源桥(dual active bridge,DAB)变换器的扩展移相(extended phase shift,EPS)控制优化策略存在数学模型不完整、工作模式不全面、优化目标单一、无法在线优化等问题.为此在全面分析EPS的工作模式和各模式传输功率、回流功率及电流应力数学模型的基础上,提出了一种EPS控制的回流功率和电流应力复合优化控制策略,优化目标是在保证回流功率最小的前提下优化电流应力,在分析比较不同工况下各模式性能优劣的基础上,根据优化目标选取部分模式采用有约束极值求解法得出复合最优控制路径,进而设计了EPS复合优化闭环控制器.最后,通过实验对所提控制策略进行了验证.实验结果表明,与已有控制策略相比较所提出控制策略降低了DAB变换器的回流功率和电流应力,提升了DAB变换器效率.

The complex and ever-changing harmonics in grid voltage will cause performance deterioration of the frequency-locked loops (FLLs). Although various measurements had been adopted to attenuate the deterioration, they had to make the tradeoff between the dynamic and steady-state characteristics generally. Consequently, a novel single-phase FLL that can adaptively adjust the dynamic and steady-state performance was proposed in this article. The proposed FLL regards the damping ratio of second-order generalized integrator-FLL (SOGI-FLL) as a time-varying parameter rather than a constant, and adjusts the damping ratio adaptively, so the proposed FLL was named SOGI-FLL with damping ratio adaptation (DASOGI-FLL). The adaptive mechanism is to decrease the damping ratio as frequency estimation error decreases and vice versa. To realize the mechanism, a novel variable was constructed to indirectly correlate the damping ratio with frequency estimation error. An objective function containing the constructed variable for damping ratio adaptation was designed, and the adaptive algorithm was derived by using the gradient ascent method. Then, the convergence analysis, parameter design, and digital implementation of the algorithm were elaborated. Finally, the results of simulation and experiment reveal that, benefits from the damping ratio adaptation, DASOGI-FLL can achieve rapid convergence, strong filtering capability, and high estimation accuracy simultaneously.

滤波器级联型锁频环可以抑制电网电压中非基频分量对频率估计的影响,适用于直流偏置严重和谐波复杂多变的场景,但是难以同时兼顾动态和稳态性能.分析对比了级联二阶广义积分锁频环(cascaded second-order generalized integrator frequency-locked loop,CSOGI-FLL)和四阶广义积分锁频环(fourth-order generalized integrator frequency-locked loop,FOGI-FLL)两种典型的滤波器级联型锁频环,推导并建立了两者传递函数和线性模型,采用振荡指标法整定两者的控制参数,证明了FOGI-FLL的参数设计灵活性优于CSOGI-FLL.针对FOGI-FLL分析了中频宽和幅值穿越频率影响其动态和滤波性能的规律,提出了根据电网电压估计误差自适应调整FOGI-FLL幅值穿越频率的方法,从而实现FOGI-FLL动态和滤波性能的自适应调节,称其为穿越频率自适应的四阶广义积分锁频环(FOGI-FLL with crossover frequency adaptation,CFAFOGI-FLL).最后,实验对比了CFAFOGI-FLL、SOGI-FLL、CSOGI-FLL和FOGI-FLL的各项性能.实验结果表明,CFAFOGI-FLL相较于其他比照技术可以兼顾动态和稳态性能,能够同时满足收敛速度快、估计精度高、滤波能力强的应用要求.

Wireless power transfer (WPT) is becoming increasingly popular in stationary electric vehicle charging. Unfortunately, the adverse health effects due to the stray magnetic field created by the WPT coils have increasingly caused concern. However, the traditional stray magnetic field optimization design method based on finite element simulation is time-consuming and resource intensive. In this paper, a numerical method to reduce the stray magnetic field around the asymmetrical wireless power transfer coils is proposed while maintaining the transmission power constant. The formulas of the stray magnetic field around the WPT coils are derived, and the distribution characteristics of the stray magnetic field are analyzed in detail. The stray magnetic field around the asymmetrical wireless power transfer coils is optimized by the numerical method, and the number of the turns for the WPT coils corresponding to the minimum stray magnetic field intensity is obtained. The effectiveness of the numerical method is verified via the finite element analysis tool JMAG, and it is proved that the numerical method require less computational time than the finite element simulation. The experiments have also been carried out to evaluate the validity of the theoretical analysis.

文章将三相并联型有源电力滤波器(SAPF)作为研究对象,先分析了PI与重复控制(RC)相结合的传统复合电流控制策略,该策略中的重复控制器在对周期性正弦信号实现高精度追踪的同时会放大高频谐波,对补偿效果产生影响.为此,提出了基于离散傅里叶变换(DFT)的改进重复控制器,改进结构不仅能针对特定谐波进行补偿,还具有更快的响应速度,与PI结合后的复合控制器则具有更为优异的稳态性能和动态特性.最后通过Matlab仿真结果验证了所提策略的有效性.

无通信前提下,直流微电网中储能单元常用的控制策略难以实现储能荷电状态(state of charge,SOC)均衡、最大化新能源利用率和母线电压支撑三方面的平衡控制,提出一种基于荷电状态的直流微电网中多储能单元分级运行控制方法.首先,考虑微电网多运行状态下对储能单元的不同需求,将储能单元状态划分为5种工作模式,且各模式的电压区间是根据SOC动态调节的.利用直流母线电压信号作为工作模式判据,各储能单元根据SOC大小投入充放电,实现分级运行.随后,功率调节控制根据储能单元各模式的电压区间自动调整下垂曲线,使投入运行的储能单元间根据SOC合理分配功率.最后,搭建了Matlab/Simulink仿真模型,仿真结果表明所提控制策略在无通信条件下可实现各储能单元SOC均衡,并且能够实现与其他源储单元协调运行,以最大化新能源利用率,避免了工作模式切换过程中母线电压大幅波动,证明了所提控制策略的可行性和有效性.

At the start-up moment, three-phase PWM rectifier generates a large inrush current on the AC side generally, which may cause electromagnetic interference and overcurrent protection, even damage to the switching device. In order to suppress the inrush current at start-up moment, the reference soft-start methods based DC Voltage and AC current are proposed respectively. However, suppression effects of such method are imperfect, and existing methods can hardly suppress the inrush current in the first few switching cycles after the rectifier is started. To solve the problem, the generation mechanism of inrush current is analyzed deeply in this paper from the perspective of switching mode and modulation ratio of the PWM rectifier, and mathematical model of three-phase PWM rectifier on each switching mode is derived. The impact of initial modulation ratio on amplitude of inrush current is obtained. Therefore, in this paper, a start-up inrush current suppression method based dual parameters soft-start, which are modulation ratio and DC voltage reference respectively, is proposed. Finally, the simulation and experimental results show that the proposed method can effectively eliminate the inrush current during the whole start-up procedure of the PWM rectifier.

针对多源储结构的独立直流微电网,提出考虑多储能系统功率分配的独立直流微电网协调控制策略,以实现源储能源利用率最大化与多储能系统间功率合理分配两方面的平衡控制,提升微网持续供电能力。根据直流母线电压信号将微网系统运行划分为5种工作模式,以协调源储运行,保证光伏能源利用率最大化及储能系统出力充足。同时,直流微电网工作模式切换过程中源储控制器保持不变,并根据当前运行状态自动调节自身运行曲线,维持系统功率平衡和母线电压稳定。其中,基于自适应功率控制的光伏系统控制方法根据母线电压自动调节光伏系统运行点追踪或偏离最大功率点,实现最大功率点跟踪（maximum power point tracking,MPPT）模式与降功率模式间的平滑切换。其次,基于荷电状态（state of charge, SOC）的自适应功率下垂控制器根据储能单元自身SOC调节其下垂曲线,实现系统功率在多储能单元间的动态分配,避免过充过放。最后,通过搭建Matlab/Simulink仿真模型,验证了所提方法的有效性。

针对扰动观察法在最大功率点(maximum power point,MPP)附近存在振荡、跟踪步长与跟踪精度无法兼顾等问题,提出一种基于β参数的最大功率点跟踪算法,通过分析β-U曲线,在跟踪过程中分别采用变步长占空比扰动法和模糊控制法,进而提高系统跟踪速度和稳态精度.为了验证该方法的有效性,在Matlab平台对光伏系统最大功率点跟踪的稳态和动态性能进行仿真,并用“可编程直流电源”来近似模拟光伏系统进行实验研究,仿真和实验结果表明所提出的方法具有较高的稳定性能和良好的动态性能,能有效提高系统跟踪速度和控制精度,实现最大功率点跟踪.