无模型自适应控制策略在动态电压恢复器中的应用研究

针对传统的动态电压恢复器前馈控制方法存在稳态误差、对电网中的扰动不敏感等问题,提出了一种基于无模型自适应控制策略的动态电压恢复器系统的设计方案。该方案不需要建立动态电压恢复器系统的数学模型,仅根据受控系统的负载瞬时电压和输入电压来提取系统中的有效信息,经无模型自适应控制器处理后去控制逆变器产生补偿电压,该电压经LC滤波器滤除谐波后叠加到电网中,从而可保证负荷侧电压的稳定性。仿真结果验证了该方案的正确性和可行性。     

矿用动态电压恢复器优化组合补偿策略

针对长时间电压跌落下矿用动态电压恢复器直流链路电容储能利用率较低的问题,提出了一种从完全补偿法到同相补偿法的优化组合补偿策略,即2种补偿策略之间平滑缓慢过渡,从而抑制跌落时刻的负载电压畸变,降低动态电压恢复器注入电压幅值,延长动态电压恢复器的补偿时间。实验结果表明,该策略在平衡和不平衡电压跌落条件下均能正确可靠地补偿电网电压跌落。     

动态电压恢复器控制策略研究

动态电压恢复器是抑制电压跌落对敏感负荷影响的有效装置。当动态电压恢复器工作在不对称电压下时,逆变器将会持续地从电源侧吸收有功功率,引发直流侧电压泵升,严重时会损坏储能及功率开关器件。针对该问题,文章提出一种复合控制策略,即采用相移控制技术来减少逆变器对有功能量的吸收,从而抑制动态电压恢复器直流电压的泵升;采用双闭环控制技术对电网电压跌落进行抑制,提高了负载的稳定性。仿真结果表明,该复合控制策略可使动态电压恢复器具有更好的负载适应性,且使直流侧电压得到很好的抑制。     

一种用于动态电压恢复器的电压跌落检测算法

针对传统的电压跌落d-q检测算法和Hilbert检测算法在补偿快速性和抗干扰性方面存在矛盾的问题,提出了一种将d-q检测算法与Hilbert检测算法相结合的电压跌落检测新算法:对电网侧电压信号采样后,经d-q检测单元得到谐波补偿波形;然后滤除3次谐波,滤波后的信号再经Hilbert检测单元得到电压幅值补偿波形;叠加该2种补偿波形可确定最终的补偿波形。仿真结果表明,该检测算法对于含3次谐波的电压跌落补偿效果较好,兼具补偿快速性和抗干扰能力。     

基于配电网电压跌落问题的DVR研究

介绍了电压跌落的基本概念，分别从动态电压恢复器（DVR）的基本结构，原理和检测方式等方面做了简要介绍，系统研究了其控制策略。     

三单相结构的动态电压恢复器的研究

针对电网中日益严重的电压跌落、闪变、不对称、谐波等电能质量问题，提出了采用动态电压恢复器来进行有效治理，分析了DVR的工作原理和整个电路的控制方法，通过在电磁暂态分析软件PSCAD仿真，验证了DVR能在极短的时间内极好的补偿各种电压畸变问题，从而保证各种电力负荷对电能质量日益提高的要求。     

动态电压恢复器检测算法的研究与仿真

介绍了动态电压恢复器的基本工作原理和现有的电压暂降检测方法,在此基础上提出了一种基于最小二乘法的检测算法.该算法能够在电网电压出现三相不平衡暂降时,快速分离出基波正序分量,并结合补偿策略得到所需的电压补偿量,实时性较强.     

含非线性负载的逆变器虚拟同步发电机控制策略

针对逆变器的负载侧接入非线性负载会引起逆变器输出电压发生畸变,甚至会损坏逆变器的问题,基于虚拟同步发电机(virtual synchronous generator, VSG)控制的逆变器,从VSG控制的角度出发,提出一种VSG谐波电压补偿控制策略。该控制策略通过向VSG功率控制环提供适当的谐波参考电压,将参考电压与传统VSG参考电压叠加,对逆变器输出电压进行补偿,降低逆变器输出的谐波电压。最后,通过仿真和实验对比谐波电压补偿前后的控制结果,验证了所提控制策略的可行性和有效性。     

基于电网电压定向的光伏并网逆变器系统研究

针对传统的光伏并网系统逆变控制策略存在控制复杂、谐波含量多的问题,提出了一种基于电网电压定向的光伏并网逆变器直接电流控制方法,给出了以TMS320F2812为主控制器的三相光伏并网逆变器系统的硬件及软件设计。该逆变器直接电流控制方法采用过零检测电路测量电网电压的过零点时刻,得出过零点时刻的电网电压的旋转角度,从而得到逆变器输出电压的幅值和相位;采用SVPWM技术控制IPM的开断,使逆变器输出上述幅值和相位的电压,从而实现单位功率因数并网发电功能。实验结果表明,该逆变器直接电流控制方法简单,逆变器输出电流与电网电压基本保持相同的频率和相位,并网发电功率因数接近于1。     

应用于感应电机矢量控制中的逆变器死区补偿

为了减小电压源型逆变器死区时间引起的输出电压畸变,对死区产生的原因进行分析,总结出三点原因,列出误差电压计算公式,最后运用到感应电机矢量控制中,对u_a、u_b、u_c三项输入到逆变器中的电压进行补偿。该补偿策略首先计算控制周期内的误差时间,算出误差时间与电流的对应关系,最后将算出的周期T_S内误差电压补偿到逆变器输入端上。通过补偿误差电压,降低了电流谐波对控制系统的影响,同时电网侧的能量利用率得到了提高。实验结果表明,该策略对电流波形起到了改善作用。     

A new control method for Dynamic Voltage Restorer with asymmetrical inverter legs based on fuzzy logic controller

Dynamic Voltage Restorer (DVR) is used in power distribution system to protect sensitive loads in voltage disturbances. The performance of DVR is related to the adopted configuration and control strategy used for inverters. In this paper, an asymmetrical voltage-source inverter controlled with fuzzy logic method based on hysteresis controller, is used to improve operation of DVR to compensate voltage sag/swell. Simulation results using MATLAB/Simulink are presented to demonstrate the feasibility and the practicality of the proposed novel Dynamic Voltage Restorer topology. Total Harmonic Distortion (THD) is calculated. The simulation results of new DVR presented in this paper, are found quite satisfactory to eliminate voltage sag/swell.     

双馈系统在电网故障下不间断运行的研究

为更好地研究风力发电机在一定的电网电压跌落故障下的动态响应,以单台1.5 MW双馈风力发电机(DFIG)为研究对象,设计了Crowbar电路,通过构建电网电压跌落仿真模型,分别对机端电压、电流、转子电流、输出的有功功率和无功功率、直流侧电压、电磁转矩在故障期间的动态响应进行了仿真。探讨了相应的控制策略,为进一步研究低电压穿越标准下的控制策略提供了依据,同时也为研制兆瓦级变频器打下基础。测量结果表明这种控制方式能使DFIG在电压跌落故障下实现不间断运行,有效提高了DFIG风电机组运行的可靠性。     

基于改进同步坐标变换的电压凹陷检测方法

提出一种新的基于改进同步坐标变换的电压凹陷检测方法。该方法针对单相凹陷,只需单相电压数据,对凹陷电压及其导数进行同步坐标变换,然后再对变换的结果进行低通滤波,得到含基波幅值和相位的直流分量。该方法不需对电网电压锁相,只需两个采样点数据就可准确求出基波的幅值和相位,所检测的凹陷起始时间没有延时,截止时间误差小。该方法原理简单,计算量小,具有工程实用意义。     

电网电压不对称跌落下直驱风电系统控制策略

针对电网电压不对称跌落下直驱风电系统并网运行过程中出现的直流环节过电压、并网电流畸变、并网功率波动问题,在直驱风电系统并网变换器的直流环节并联超导磁储能系统;同时在分析电网电压不对称跌落下网侧变换器数学模型的基础上,采用抑制并网功率波动的正负序电流控制对网侧变换器的控制策略加以改进,从而稳定直流环节电压、改善并网电流品质、抑制并网功率波动。仿真结果验证了该控制策略的正确性和有效性。     

Hybrid Renewable Energy Source Combined Dynamic Voltage Restorer for Power Quality Improvement

In this paper, the hybrid photovoltaic-thermoelectric generator (PV-TEG) combined dynamic voltage restorer (DVR) system is proposed for the power quality disturbances compensation in a single-phase distribution system. The stable and precise level of input voltage is essential for the smooth and trouble-free operation of the electrically sensitive loads which are connected at the utility side to avoid system malfunctions. In this context, the hybrid PV-TEG energy module combined DVR system is proposed in this paper. With the support of the hybrid energy module, the DVR will perform the power quality disturbances compensation effectively with needed voltage and /or power. In the proposed system, the PV and TEG energy sources are connected electrically in series to produce adequate voltage for the DVR operation and the fractional factor-based variable incremental conduction (FFVINC) maximum power point tracking (MPPT) control algorithm is employed to extract the possible maximum power from the PV array. The intelligent fuzzy logic controller (FLC) is chosen for implementing the MPPT control algorithm. The half-bridge voltage source inverter (VSI) circuit and in-phase voltage compensation technique are used in the DVR for better power quality disturbances compensation. The performance and usefulness of the proposed DVR system are investigated by an extensive simulation study with four different modes of operation, the study results are confirmed that the proposed system promptly identifies the power quality disturbances for compensation. Moreover, the investigation proved that the combined PV and TEG energy module can provide better energy efficiency in converting solar irradiation into electricity.     

一种新型的电梯能量回馈并网系统

针对普通电梯变频器不能回馈再生能量的缺点,设计出一种并网逆变器,将再生能量转化成电能回馈给电网。该回馈系统采用重复控制与电压前馈控制策略。为验证所提出的算法,搭建了基于TMS320F2812的并网逆变系统实验模型。实验结果表明该系统具有功率因数高,动态响应快,鲁棒性能好,抗干扰能力强等优点,可以有效的将再生制动能量回馈给电网,达到节能的目的,应用前景良好。     

Direct power control of grid connected voltage source inverters using port-controlled Hamiltonian system

This paper presents a new direct active and reactive power control (DPC) scheme for a three-phase grid connected voltage source inverter (VSI) based on the passivity viewpoint using the port-controlled Hamiltonian (PCH) system. The proposed controller consists of feedforward and feedback parts. The feedforward part (the reference inputs) is generated through the flatness of the dynamics of the VSI model, which makes the error dynamics in the form of PCH system. The nonlinear feedback part is designed to enhance the damping of the error dynamics by using its Lyapunov function. The proposed control method has an ability of the finite time reaching condition similar to sliding mode control (SMC). Moreover, the exponential stability and uniform performance are guaranteed over all operating points without need for reaching a certain manifold. The proposed method is validated by using an experiment through hardware-in-the-loop system with a digital signal processor. The experimental results for the proposed method are compared with those using SMC-DPC method. The proposed method significantly reduces the total harmonic distortion in the output current without deteriorating the transient response of the active and reactive powers. In addition, it provides robust performance against the line impedance variations and the grid voltage sag.