新型高压大容量混合有源电力滤波装置的研究

提出一种新颖的高压大容量混合型有源电力滤波电路(HAPF).无源支路在补偿无功功率的同时还可以滤除因非线性负载产生的特征谐波电流.有源部分通过耦合变压器与基波串联谐振电路并联构成串联谐振注入式混合有源滤波器.详细介绍该新型结构的基本工作原理,分析其谐波补偿特性及谐振抑制特,并对其有源部分的参数设计进行研究.依此方法为某矿厂研制了高压大容量混合型有源电力滤波装置,运行结果表明该装置能很好的满足工程需要.     

基于粒子群算法的无源滤波器多目标优化设计

摘要：针对无源滤波器参数优化问题,将无源滤波器的最小费用、谐波电压畸变率、谐波电流残留率、以及无功功率补偿容量作为设计的优化目标,改进了传统的粒子群算法,引用惩罚函数将问题转化为无约束优化问题。本设计算法是采用改进多目标粒子群优化算法与惩罚函数相结合的算法为无源滤波器参数优化设计提供了一种新的优化方法。     

Load compensation based on frame considering low-order dominant harmonics and distorted power system

In this paper, by considering voltage distortion and frequency variation, the control strategy of synchronous reference frame (SRF) for three-phase shunt active power filter has been improved. In the SRF compensation method a conventional low pass filter (CLPF) is used to extract the dc component of the d-axis current (I_d). Unfortunately in the presence of low-order harmonics of the load current (second and third ones), the transient response time is increased. If the amplitude of these harmonics are high, the distortions in CLPF output signal are increased, and as a result, the desired compensation cannot be achieved. In this paper to overcome this problem, a novel numerical LPF is designed and implemented based on variable forgetting factor-recursive least squares (VFF-RLS). The advantages of the proposed filter over CLPFs include independence of the load current harmonic components, fast dynamic and high accuracy of the response. Moreover, due to the malfunction of the conventional phase locked loop (PLL) in polluted and variable frequency environment, a second order generation integrator-frequency locked loop (SOGI-FLL) based on fuzzy logic controller (FLC) and wavelet transform (WT) is proposed. Effectiveness of the proposed method is evaluated with both simulations and experimental results in a three-phase power system.     

Using passive filters to minimize torque pulsations and noises in surface PMSM derived field oriented control

This paper describes a new dissipative passive filter system to minimize torque pulsation and current harmonic noises in surface PMSM when derived with field oriented control algorithm. The passive filter system consists of complex dissipative filter cascaded by low pass filter. The complex filter has two setting frequency points, one at inverter switching frequency and the other at some average selected frequency point. The filter system is affecting the inverter switching frequency in such a way to decrease stress on the inverter switching elements and reducing the severe of dv/dt on the motor. The filter system uses series dissipative elements to assist in reshaping of the applied voltage waveform in order to provide almost semi-sinusoidal voltage to the motor windings. The simulation results show that the proposed filter system is effectively minimized torque pulsations and harmonic noises in surface PMSM.     

A novel harmonic-free power factor corrector based on T-type APF with adaptive linear neural network (ADALINE) control

A novel harmonic-free power factor correction (PFC) topology based on T-type active power filter (APF) is proposed in this paper. The proposed system has better stability characteristics compared to conventional shunt APF topologies and it is a natural filter for the non-linear load harmonic disturbances. The tuned passive filters are connected at the ac-side of the rectifier load, which are designed to provide fundamental reactive power compensation and eliminate majority of load harmonics in order to minimize the power rating and heat dissipation of the voltage source inverter (VSI). The control scheme is based on a decoupled state-space equations of the T-type APF using separate proportional-integral controllers in d-axis and q-axis of rotating reference frame synchronized with grid voltages, respectively. The fundamental components of load-side currents are feed-forwarded in the current control loop using two groups of synchronous frame adaptive linear neural networks (ADALINEs) to ensure a fast dynamic response. A proportional-integral controller is adopted in the outer voltage loop for balancing the active power flow of the dc-side capacitor of the VSI. The proposed power factor corrector topology is studied analytically and by simulation under various scenarios using Matlab/Simulink. The validity and effectiveness of the proposed topology as well as its control schemes are substantially confirmed by the simulation results.     

Bacterial foraging optimization and adaptive version for economically optimum sitting,sizing and harmonic tuning orders setting of LC harmonic passive power filters in radial distribution systems with linear and nonlinear loads

This paper presents bacterial foraging optimization (BFO) algorithm and its adaptive version to optimize the planning of passive harmonic filters (PHFs).The important problem of using PHFs is determining location, size and harmonic tuning orders of them, which is reach standard levels of harmonic distortion with applying minimum cost of passive filters.In this study to optimize the PHFs location, size and setting the harmonic tuning orders in the distribution system, considered objective function includes the reduction of power loss and investment cost of PHFs. At the same time, constraints include voltage limits, number/size of installed PHFs, limit candidate buses for PHFs installation and the voltage total harmonic distortion (THDv) in all buses. The harmonic levels of system are obtained by current injections method and the load flow is solved by the iterative method of power sum, which is suitable for the accuracy requirements of this type of study. It is shown that through an economical placement and sizing of PHFs the total voltage harmonic distortion and active power loss could be minimized simultaneously.The considered objective function is of highly non-convex manner, and also has several constraints. On the other hand due to significant computational time reduction and faster convergence of BFO in comparison with other intelligent optimization approach such as genetic algorithm (GA), particle swarm optimization (PSO) and artificial bee colony (ABC) the simple version of BFO has been implemented. Of course other versions of BFO such as Adaptive BFO and combination of BFO with other method due to complexity of harmonic optimization problem have not considered in this research.The simulation results for small scale test system with 10 buses, showed the significant computational time reduction and faster convergence of BFO in comparison with GA, PSO and ABC. Therefore in large scale radial system with 34 buses, the proposed method is solved using BFO.The simulation results for a 10-bus system as a small scale and 34-bus radial system as a large scale show that the proposed method is efficient for solving the presented problem.     

改进型单位功率因数谐波检测算法在三相并联型APF中的应用研究

为了降低电网电压不对称或畸变对UPF谐波检测算法的影响,通过引入锁相环电路的改进型UPF谐波检测算法产生基波正序电压,对有功功率进行修正,抑制了电压畸变的影响,同时提高了检测的实时性。在Matlab上对补偿前后电源侧电流波形进行对比研究,验证了改进型UPF谐波检测算法的可行性。实验结果表明,采用改进算法后,电源侧电流谐波成分中谐波含量最高的5次谐波含量由补偿前的22.8%降低为补偿后的8.1%,负载电流主要次谐波成分得到了有效抑制,实现了抑制谐波的目的。     

An ant direction hybrid differential evolution heuristic for the large-scale passive harmonic filters planning problem

This article presents a heuristic which combines the orthogonal array experiment technique and an ant direction hybrid differential evolution algorithm (ADHDEOA) for planning of a large-scale passive harmonic filters problem. The addressed problem has a multi-bus and under abundant harmonic current sources in the system. In this study, an orthogonal array is first conducted to obtain the initial solution. Next, an ant direction hybrid differential evolution (ADHDE) is applied to search for a near optimum solution. The objective is to minimize the cost of the filter, the total demand distortion of harmonic currents and the total harmonic distortion of voltages at each bus simultaneously. In order to determine a set of weights of each term in the objective function, the simplest and most efficient form of triangular membership functions has been considered. The designed heuristic ADHDEOA is applied to a practical harmonic problem in a steel plant, and three design schemes are compared to demonstrate the performance of the ADHDEOA.     

基于混合预测策略的改进型并联有源电力滤波器无差拍控制

针对传统的无差拍电流跟踪控制受时延影响实际上是差一拍控制,提出一种改进的无差拍控制.该方法提前两个采样周期预测出有源电力滤波器(APF)指令电流,提前一个采样周期预测出逆变器输出电流,从而实现真正意义上的无差拍控制.同时,提出一种综合考虑负载谐波电流稳态和动态过程的混合预测策略,使上述预测过程更加准确、快速.仿真实验结果表明,基于该方法的APF在负载稳态和变化时均具有良好的补偿效果.     

Current control for a shunt hybrid active power filter using recursive integral PI

This paper presents a current control method for a shunt hybrid active power filter （HAPF） using recursive integral PI algorithm. The method improves the performance of the HAPF system by reducing the influence of detection accuracy, time delay of instruction current calculation and phase displacement of output filter. Fuzzy logic based set-point weighing algorithm is combined in the control scheme to enhance its robustness and anti-interference ability. The proposed algorithm is easy to implement for engineering applications and easy to compute. Experiment results have verified the validity of the proposed controller. Furthermore, the proposed recursive integral PI algorithm can also be applied in the control of periodic current as in AC drivers.     

MGWO-PI controller for enhanced power flow compensation using unified power quality conditioner in wind turbine squirrel cage induction generator

Power quality is considered to be the major challenging one in the realization of the smart grid. So as to compensate for the issues occurring in power quality, active power filter (APFs) is mainly chosen as they are capable of filtering fast and has some active compensation. Also, load current related power quality constraint can be solved, such as unbalanced power, huge (Total harmonic distortion) THD level, and reduced power factor. For correcting the inappropriate supply of voltage and load current, the unified power quality conditioner (UPQC) and an effective integration of wind turbine are employed. A UPQC is a group of both shunt and series APF in a continuous manner having a conventional DC link capacitor. The voltage control of the DC link capacitor is significant in attaining a preferred performance on UPQC. In this paper, the UPQC with a Modified Grey Wolf Optimization (MGWO) based PI controller integrated with renewable energy like Wind turbine squirrel cage induction generator (SCIG) was implemented for the elimination of voltage and current harmonics imperfection precisely. Likewise, the Modified Grey Wolf Optimization (MGWO) was also exploited in UPQC. The performance analysis was made with UPQC, without UPQC, and with MGWO & UPQC and the simulation, outcomes are estimated and compared for the parameters THD values, load voltage and current. Also, the performance analysis was implemented in hardware prototype set-up and the results attained are depicted.     

适用于中高压系统的HAPF的研究与应用

着眼于电力系统对大容量谐波抑制与无功补偿的要求，通过对各种不同结构的并联混合型有源电力滤波器（HAPF）进行比较分析，提出将串联谐振注入式HAPF应用于中高压系统，同时结合某铜箔厂大型整流装置谐波抑制和无功补偿的工程实例，从项目成本和治理效果两方面具体分析串联谐振注入式HAPF的应用优势，并详细介绍装置的一般设计方法及其软硬件构成。其中的一些设计思路和工程经验还可推广到其它大型滤波和无功补偿装置的设计和应用中，为推进大功率的HAPF的实用化进程提供有益的参考和借鉴。     

基于模糊控制的三电平有源电力滤波器研究

提出了一种基于ip-iq谐波电流检测、模糊PI电流控制和空间矢量脉宽调制的三电平有源电力滤波器的控制方案;建立了三电平有源电力滤波器的数学模型,详细介绍了三电平有源电力滤波器直流侧电压稳定和中点电位平衡控制方法的具体实现。仿真和实验结果表明,采用该控制方案的三电平有源电力滤波器具有良好的谐波补偿效果,且能较好地稳定直流侧电压和电容中点电位。     

A DSP-based implementation of an instantaneous current control for a three-phase shunt hybrid power filter

This paper presents the design and implementation of an instantaneous current control technique for a three-phase shunt hybrid power filter (SHPF) to compensate harmonics generated by non-linear loads. The control of the SHPF is based on synchronous reference frame (SFR) method. The SHPF consists of a small-rated voltage source inverter (VSI) in series with an LC passive filter. The proposed control algorithm of the SHPF requires less number of current sensors compared to the instantaneous reactive power theory based current control algorithm, which resulting in an overall cost reduction. Proportional–Integral (PI) controller is used to control the SHPF dc-bus voltage. The inner loops ensure the shaping of the ac currents, through the control of dq current components. The outer loop regulates the dc-bus voltage to its set reference and provides the current reference to the inner current loops. The SHPF can maintain the low level of dc-bus voltage at a stable value below 50 V, which is one of its advantages in comparison to the conventional hybrid power filter. The systems performance, during both nominal and severe operating conditions, are then evaluated in real-time using the dSPACE DS1104 controller board, supported by a Matlab/Simulink Real-Time Workshop environment.     

Time-averaged non-linear systems: steady-state analysis†

A non-linear system with time averaging can be regarded as one composed of a time varying system with a variable parameter. A non-linear operation, such as squaring is performed on the signal of the system and followed by low pass filtering. This filtered signal controls, in turn, the variable parameter. This paper considers the steady state analysis of time averaged non-linear systems. The analysis covers both passive (with input) and oscillatory (no input) systems, In the passive case it is shown that the response is similar to that of a passive system with the poles shifted. The harmonic content and distortion are computed for both the oscillatory and passive case. An evaluation of the frequency is carried out for the oscillatory case. An interesting result is that the significant filter characteristic is the attenuation at twice the frequency.     

三电平并联型有源电力滤波器的无差拍控制研究

介绍了基于开关函数的三电平并联型有源电力滤波器工作原理,建立了该种有源电力滤波器的数学模型,并提出一种三电平并联型有源电力滤波器的无差拍控制方案。该方案采用ipiq法检测谐波电流,根据当前采样时刻得到的负载电流和补偿电流值预测出下一采样时刻的电流参考值,并计算出有源电力滤波器在下一个采样时刻的输出电压参考值,最后采用电压空间矢量算法得出桥臂开关信号,从而达到电流跟踪控制的目的。仿真结果表明,采用该方案的三电平并联型有源电力滤波器能够很好地对检测电流进行跟踪控制,有效抑制了谐波,且具有良好的动态响应效果。     

A multi-objective approach to optimal placement and sizing of multiple active power filters using a music-inspired algorithm

This paper proposes a new multi-objective framework for optimal placement and sizing of the active power filters (APFs) with satisfactory and acceptable standard levels. total harmonic distortion (THD) of voltage, harmonic transmission line loss (HTLL), motor load loss function (MLLF), and total APFs currents are the four objectives considered in the optimization, while harmonic distortions within standard level, and maximum allowable APF size, are modeled as constraints. The proposed model is one of non-convex optimization problem having a non-linear, mixed-integer nature. Since, a new modified harmony search algorithm (MHSA) is used and followed by a min–max technique in order to obtain the final optimal solution. The harmony search algorithm is a recently developed optimization algorithm, which imitates the music improvisation process. In this process, the Harmonists improvise their instrument pitches searching for the perfect state of harmony. The newly developed method has been applied on the IEEE 18-bus test system and IEEE 30-bus test system by different scenarios and cases to demonstrate the feasibility and effectiveness of the proposed method. The detailed results of the case studies are presented and thoroughly analyzed. The obtained results illustrate the sufficiency and profitableness of the newly developed method in the placement and sizing of the multiple active power filters, when compared with other methods.     

Design of output filter for inverters using fuzzy logic

This paper proposes a design method to improve the harmonic of output voltage of a single phase inverter with an L-C output filter using fuzzy logic controller (FLC). In practice, the harmonic characteristics of circuits are complicated and entangled. There are two kinds of harmonic sources that cause inverter output voltage waveform distortion: One is the PWM switching of inverter and the other is the nonlinear characteristics of the load. In general, PI feedback control by coefficient diagram method (CDM) is used to design the output voltage filter. The relation between the L-C value and the system time constant are described with the closed form and the filter values must be calculated repeatedly to satisfy the prescribed voltage total harmonic distortion (THD) of the system. Therefore, the MATLAB Fuzzy Logic Toolbox for the fuzzy logic control algorithm is proposed. The L-C value of the filter can be set to a fixed range in the nonlinear characteristic of the practical condition, to improve the harmonic of output voltage more effectively and to avoid repeated calculation.     

基于广义积分器的谐波电流检测方法研究

针对四桥臂有源电力滤波器的谐波检测环节,提出了一种基于广义积分器的谐波电流检测方法,分析了该检测方法的检测原理及参数k的变化对谐波电流检测效果的影响。仿真结果表明,当电网频率稳定时,该检测方法可准确地提取谐波电流中的基波分量;参数k影响检测的快速性和精确性,应合理设置;该检测方法结构简单,易于实现,对于电网电压畸变、电网频率波动及三相负载不平衡的情况有一定的适应性。     

Optimum placement of active power conditioner in distribution systems using improved discrete firefly algorithm for power quality enhancement

This paper presents an improved solution for optimal placement and sizing of active power conditioner (APC) to enhance power quality in distribution systems using the improved discrete firefly algorithm (IDFA). A multi-objective optimization problem is formulated to improve voltage profile, minimize voltage total harmonic distortion and minimize total investment cost. The performance of the proposed algorithm is validated on the IEEE 16- and 69-bus test systems using the Matlab software. The obtained results are compared with the conventional discrete firefly algorithm, genetic algorithm and discrete particle swarm optimization. The comparison of results showed that the proposed IDFA is the most effective method among others in determining optimum location and size of APC in distribution systems.