基于DSP并联有源电力滤波器的研究

以并联有源电力滤波器为研究对象,并对其拓扑结构、补偿分量的检测算法、控制策略等问题做了较系统的研究,在该基础上介绍一种基于DSP的并联型有源电力滤波器的设计。通过仿真实验对有源电力滤波器数学模型、检测算法及控制策略的有效性和实用性进行了验证。结果表明所设计的有源滤波器具有良好的谐波补偿特性、自适应补偿能力。     

并联型有源电力滤波器指定次无静差控制策略

为提高有源电力滤波器的补偿性能和动态响应,本文提出了一种基于同步旋转坐标系下的有源电力滤波器的新型的控制策略,通过与某指定次谐波频率同步旋转的旋转坐标变化,将该次谐波变成直流量进行PI调节,实现指定次谐波的检测和控制,然后反变换到与基波同步旋转的坐标系下进行指令的综合和PI再调节,理论上可以实现对任意指定次谐波的无静差补偿,与传统的电流环控制方法相比,补偿精度显著提高,动态响应好,在负载变化剧烈的场合具有明显的优势,也可以对非线性负载产生的谐波和无功电流进行全部补偿,以达到灵活补偿的目的。在改进的控制算法中可以灵活加入相角补偿,以补偿系统的检测环节和电流控制环引入的固有时延。理论分析和试验结果证明了提出的控制策略的优越性。     

并联型有源电力滤波器直流侧电压柔性控制策略

针对并联型有源电力滤波器的直流侧电压控制特点,提出了一种对直流侧电压进行柔性控制的并联型有源电力滤波器控制策略。该策略中,在直流侧电压控制部分引入反馈低通滤波器,削弱直流侧固有谐波对输出电流控制的影响;在电流控制的输出部分通过增加直流侧电压前馈系数,抵制在变换桥中可能引入的直流侧电压谐波影响。仿真结果表明直流侧电压柔性控制策略能够降低APF系统补偿后的电源电流总谐波畸变率,从而改善并联型有源电力滤波器的谐波补偿性能。     

基于重复控制下的双变流器串并联补偿式UPS

分析了三相双变流器串并联补偿式UPS的运行特性、数学模型和基于同步旋转坐标系下的控制策略，同时进一步提出一种改进控制策略，即在同步旋转坐标系下采取PI加重复控制。提出的控制策略可以实现双变流器串并联补偿式UPS全部控制功能：在电源电压不是额定值且含有谐波电压、负载有谐波电流和无功电流的情况下，电源输入电流被控制为正弦波，cosφ为1，负载电压不论带线性或非线性负载均被控制为额定值正弦波。     

强谐波环境下的无功功率补偿技术

非线性功率用电设备产生谐波电流,导致电磁干扰、功率因数降低,由电容器、串联电抗器组成的谐波滤波装置具有谐波滤除和无功补偿两大功能。工作时不会像传统电容器组补偿那样,在提高功率因数的同时对高次谐波进行放大,而是对谐波进行吸收,提高电源质量。在电抗性补偿系统里,根据需要被补偿的功率计算得出电容,串联谐振电路的串联谐振频率由...     

基于改进比例谐振控制的三相四桥臂有源电力滤波器研究

在有源电力滤波器电流内环控制环节,为了实现对交流量的稳态无误差跟踪,以及对主要特征次谐波和低次谐波进行充分补偿,针对谐振控制器可以无静差地跟踪交流参考量以及PI控制可以无静差地跟踪直流量的特性。采用了一种基于abc静止坐标系下的比例-积分-多频谐振控制策略,对含量较高的主要特征次谐波和低次谐波进行选择性补偿,有效的降低了系统的总谐波畸变率。最后,通过仿真和实验对比分析了上述控制策略的可行性。     

基于TMS320LF2812的并联型有源电力滤波器的设计与实现

针对谐波抑制和无功补偿的问题,对有源电力滤波器进行一系列研究,阐述了有源电力滤波器的基本原理以及控制策略。基于TMS320LF2812设计了有源电力滤波器,包括DSP控制板、电压采样电路,电流采样电路以及IPM功率单元的设计,并给出了有源电力滤波器的软件设计。最后利用MATLAB仿真软件对所涉及的有源电力滤波器进行仿真,验证了有源滤波器系统的正确性以及谐波补偿电流和滞环比较控制模块的有效性。     

考虑电网谐波的SVG控制策略研究

通过静止无功发生器(SVG)单相等效电路分析其工作原理并建立三相等效电路数学模型,探讨具有谐波抑制功能的SVG控制策略,依据控制原理搭建MATLAB/Simulink仿真模块,仿真结果验证了控制策略的可行性和正确性,为电网的无功补偿及谐波治理工作提供理论基础。     

不平衡电网电压下三相PWM整流器控制策略的研究

在不平衡电网电压下三相电压型PWM整流器的优越性能受到了很大的影响,其原因是由于直流电压产生了奇次谐波以及交流的电流产生了偶次谐波。三相PWM整流器直流侧电压的二次谐波以及在交流侧电流所产生的负序分量都将对整流器负载性能产生影响,同时还将影响直流侧电容寿命。文章提出一种新型不平衡观测器及其控制策略可有效地对不平衡电压进行补偿。通过此控制策略可同时抑制直流侧电压的2次谐波以及减小网侧电流的不平衡度。分析及仿真结果证明了此控制策略的有效性。     

基于电流间接控制的STATCOM系统仿真研究

静止同步补偿器（STATCOM）因具有无功补偿响应速度快、连续调节范围宽等优点,已经现代电力系统中重要的补偿设备之一。对不同控制策略STATCOM的补偿效果进行研究是该领域值得关注的关键问题。在此对STATCOM主电路进行四重化的结构优化,有效降低谐波含量,控制策略上采用电流间接控制方法,在Matlab/Simulink平台上实现了补偿系统的建模和仿真,通过比较补偿前后系统功率因数的变化,验证了所采用控制策略的正确性和有效性。     

一种多旋转坐标系下的死区谐波电压补偿方法

分析了死区时间对逆变器输出电压谐波的影响,结合逆变器在旋转坐标系上的数学模型,提出了多旋转坐标系下死区谐波电压补偿策略,即在旋转坐标系下在线检测死区谐波电压,通过谐波电压的反馈控制对死区谐波电压进行消除。该策略无需对桥壁电流极性进行判断即能达到消除死区电压的目的。最后,在工频逆变器上通过实验验证了该补偿方法对谐波电压检测以及死区谐波电压消除的有效性。     

无变压器型混合有源滤波器及其控制策略研究

在对一种无变压器型混合有源滤波器的电路拓扑和参数设计方法进行分析研究的基础上,提出一种采用电网谐波电流作反馈控制与负载谐波电流作前馈控制的复合控制策略,并用SIMULINK建立仿真模型进行仿真分析。通过与仅采用电网谐波电流作反馈控制时的仿真结果进行比较,可以看出使用这种复合控制方法,能更有效地抵消电网中的谐波电流,降低总的谐波畸变率。     

有源电力滤波器改进快速重复控制方法的研究

有源电力滤波器应具有动态响应快和稳态精度高的特点,使用传统重复控制的有源电力滤波器进行谐波补偿时系统的响应速度较慢。对此,根据有源电力滤波器的数学模型,提出一种将比例控制与快速重复控制相并联的复合控制方法。通过建立电网在dq同步旋转坐标系下的数学模型,可以将指令电流中的基波分量转化为直流量,并且将2k±1次谐波分量转化为2k次交流量。这种控制策略可以消除所有奇次谐波并提高系统动态响应速度。通过仿真建模,将所提控制策略与传统重复控制进行比较,仿真结果验证了所提控制策略在保证稳态精度高的同时,可以有效地提高动态响速度。     

A Multipulse-Structure-Based Bidirectional PWM Converter for High-Power Applications

Multipulse converters are suitable for high-power application with the merits of low switching frequency and perfect harmonic performance. But less controllability and poor regulation lead the restriction on its application. A bidirectional pulsewidth modulation (PWM) converter based on multipulse structure is proposed in this paper, which has the same perfect harmonic performance with very low switching frequency. A special sequential sampling space vector modulation technique, which has the sampling sequence from the lagging module to the leading module, is proposed to make the converter controllable like conventional PWM converters. The harmonic performance and linear regulation capability are analyzed theoretically. The converter is modeled in detail, and an instantaneous feedback control strategy with phase delay compensation and decoupling control is also proposed. The controller parameters are optimized to get high dynamic performance with adequate phase margin and gain margin. A 3-kVA prototype is built, and the simulation and experiment results validate that the proposed converter is quite suitable for high-power conversion.     

Dual closed-loops current controller for a 4-leg shunt APF based on repetitive control

ABSTRACT

Current repetitive control strategy for a 4-leg APF is usually of a poor speed in responding to the drastic changes in load harmonic profile. In this paper, a dual closed-loop current controller composed of a repetitive control-based outer loop and a PI-based inner loop is proposed to improve the performance of a 4-leg APF, with a focus on response speed and harmonic current compensation gain. The principle of the dual loop controller is explained in detail, and the stability of the system is analysed thoroughly. To further decrease the inherent time delay associated with the PWM strategy, a zero-sequence-voltage-based PWM strategy is proposed to solve the complexity in the implementation of 3D-SVPWM methods. By formulating the relationship between the duty ratio of the neutral leg control pulse and the zero-sequence-component of the reference voltages, the duty ratios of the other three legs can be calculated conveniently. The simulation and lab experiment results are provided to verify the correctness and effectiveness of the proposed dual closed-loop current controller and the zero-sequence-voltage-based PWM strategy.     

Controller design and implementation for industrial robots withflexible joints

A control strategy which consists of feedforward and feedback compensation loops is proposed to improve the performance of industrial robots. The feedforward loop is similar to the usual inverse-dynamics compensation. The feedback control loop uses a frequency-domain optimal controller. The design starts from the single-link case and is extended to the control of multilinkage flexible-joint robots. An experimental system consisting of a single-link robot is constructed for verifying the proposed control strategies. Experiments show good performance of the proposed control strategy in stiffening the flexible joint and in tracking desired polynomial-type trajectories     

A three-phase active power filter operating with fixed switchingfrequency for reactive power and current harmonic compensation

The performance and dynamic characteristics of a three-phase active power filter operating with fixed switching frequency is presented and analyzed in this paper. The proposed scheme employs a PWM voltage-source inverter and has two important characteristics. First, it operates with fixed switching frequency, and second, it can compensate the reactive power and the current harmonic components of nonlinear loads. Reactive power compensation is achieved without sensing and computing the reactive component of the load current, thus simplifying the control system. Current harmonic compensation is done in time domain. The principles of operation of the proposed active power filter along with the design criteria of the power and control circuit components are discussed in detail. Finally, experimental results obtained from a 5 kVA prototype confirm the feasibility and the features of the proposed system     

A Unified Artificial Neural Network Architecture for Active Power Filters

In this paper, an efficient and reliable neural active power filter (APF) to estimate and compensate for harmonic distortions from an AC line is proposed. The proposed filter is completely based on Adaline neural networks which are organized in different independent blocks. We introduce a neural method based on Adalines for the online extraction of the voltage components to recover a balanced and equilibrated voltage system, and three different methods for harmonic filtering. These three methods efficiently separate the fundamental harmonic from the distortion harmonics of the measured currents. According to either the Instantaneous Power Theory or to the Fourier series analysis of the currents, each of these methods are based on a specific decomposition. The original decomposition of the currents or of the powers then allows defining the architecture and the inputs of Adaline neural networks. Different learning schemes are then used to control the inverter to inject elaborated reference currents in the power system. Results obtained by simulation and their real-time validation in experiments are presented to compare the compensation methods. By their learning capabilities, artificial neural networks are able to take into account time-varying parameters, and thus appreciably improve the performance of traditional compensating methods. The effectiveness of the algorithms is demonstrated in their application to harmonics compensation in power systems