半波不对称控制TCR型无功补偿装置的控制策略

为解决系统电压含有2次谐波电压分量时,TCR正负半波导通电流面积不相等,向系统注入过多直流 电流分量的问题,本文提出了一种用于TCR型静止无功补偿装置,可抑制2次谐波电压影响的复合控制器,该控制器采用对TCR电流的瞬时值在每半个周期内积分求解平均值,再通过PI调节器结合系统电压的极性得出平衡调节器的控制量,控制器通过调...     

基于特征谐波电流的高压直流输电控制策略

为了降低特征谐波电流对高压直流输电产生的危害，提出基于特征谐波电流的高压直流输电控制策略。根据高压直流输电网络的组成元素以及空间分布方式，构建高压直流输电网络模型。在该模型下，利用智能电流表获取实时电流数据，提取高压直流输电电流特征。通过特征匹配识别初始数据中的特征谐波电流，计算特征谐波电流量，求解直流输电电流控制量。将控制量求解结果代入到装设的输电控制器中，从谐波电流抑制、电流裕度补偿和电流限幅等方面完成高压直流输电控制。通过测试实验得出结论：在优化设计高压直流输电控制策略的作用下，特征谐波电流畸变率为0.466%,输电电流的空间不稳定系数为0.23,均满足预设要求。     

基于新型换流变压器偏磁特性仿真研究

研究变电站优化供电问题,高压直流输电中交直流输电线路并行时换流变压器存在直流偏磁问题,直流偏磁产生的谐波严重干扰到电网的安全运行.分析了新型换流变压器在直流偏磁下的励磁电流畸变特性和谐波特性,为了提高电力系统安全保护性能,提出采用感应滤波技术来抑制直流偏磁谐波的新方法,根据新型换流变压器的参数建立交直流输电线路系统模型,对谐波特性进行仿真,仿真证明了感应滤波技术在交直流输电线路平行架设时对直流偏磁产生的谐波污染具有良好的隔离屏蔽效果,可为设计提供依据.     

滤波换相换流器的典型故障瞬态谐波仿真研究

研究直流输电系统消除故障问题,在稳态工况条件下FFT算法可以满足精度和谐波检测要求,针对系统发生故障的瞬间,系统电流中除特征谐波外,电流中存在间谐波和次谐波等分量.为了有效解决直流输电系统发生故障瞬间谐波频谱泄露,提出了一种结合能量群与消除频谱泄露的复合谐波检测算法,在建立了滤波换相换流器(Filter Commutated Converter,FCC)的HVDC输电系统的基础上,对系统发生极母线对地短路,整流侧交流母线三相接地短路及逆变侧交流母线三相接地短路三种典型故障进行了仿真研究,并对交流母线处的电流进行瞬态谐波检测.结果表明,在交流母线电流中的2次谐波含量发生激增,达到谐波屏蔽的效果,减轻了换流变压器的负担,增强了系统的稳定性,说明复合谐波检测算法在分析故障瞬态电流时,效果满足了要求.     

不平衡电网中三相脉冲调宽整流器的控制

在常规的三相整流器控制器设计中,一般均假设三相电网电压平衡,然而当实际电网不平衡时,传统双闭环控制策略将使直流侧出现严重的二次谐波功率从而严重影响整流器输出品质.鉴于此,本文在分析PWM整流器数学模型和电网不平衡条件的基础上,电压外环采用模糊PI控制,提高直流侧电压动态响应速度,电流内环采用无需进行正负序分解的正、负序电流独立控制策略,实现了不平衡电网下对三相PWM整流器的双闭环控制.仿真结果表明:所设计的控制方法保证了在不平衡条件下直流侧电压快速地稳定,有效抑制了直流侧二次谐波,提高了整流器的运行性能.     

基于稳健回归的系统谐波阻抗及用户谐波发射水平的估计方法

该文提出了一种基于稳健回归的系统谐波阻抗及用户谐波发射水平的评估方法,即通过对系统公共连接点的同步测量,获取系统中谐波电流、电压信号,并利用复加权最小二乘迭代法计算出谐波回归系数;然后以上次迭代残差函数作为权重,并将Huber函数当做影响函数,进行加权迭代计算,这样能够避免或减少回归系数受奇异值的影响;系统谐波阻抗有回归系数映射出,同时对用户谐波发射水平实施跟踪计算,以此就能对系统谐波阻抗及用户谐波发射水平进行准确的评估。另外,通过相应的仿真实验、实例分析,验证了这种评估方法的可行性。     

大功率低成本新型混合型有源滤波器的电流检测方法*

提出一种逆变器采用三相四开关结构的大功率新型混合型有源滤波器,这种结构的滤波器适用于中高压系统的无功补偿和谐波抑制。给出了系统的拓扑结构,对三相四开关逆变器的结构原理进行了分析。提出了一种单相电流的谐波检测方法和基于能量平衡的直流侧电流的检测方法,这种检测方法计算时间显著减少,系统只需检测两相电流和控制四个开关元件。将基于三相四开关逆变器的新型混合型APF进行仿真实验,仿真结果表明,提出的滤波装置具有良好的谐波波抑制和无功补偿性能,直流侧电压平衡稳定,而且大大降低了整个装置的成本和功耗。     

新趋近律的直流微电网母线电压滑模控制设计

随着直流微电网技术的快速发展,直流微电网中母线电压的稳定性控制作为直流微电网正常平稳运行的关键,也成为了研究热点之一;针对直流微电网母线电压外环易受参数摄动和负荷扰动的影响,提出了一种扩张状态扰动观测器ESO(Extend state observer)与新型趋近律的滑模控制器NRSMC(New reaching law sliding mode control)相结合的复合控制器ESO-NRSMC;该控制器采用了一种新型趋近律方法来解决抖振现象与滑模面趋近时间之间的矛盾;同时扩张状态观测器将观测到的扰动值补偿到滑模控制器中,进一步提高控制器的抗扰动能力;还构造了Lyapunov函数来验证所设计的母线电压外环闭环控制系统的稳定性;最后通过仿真证明控制器ESO-NRSMC在微电网系统参数发生变化以及负载扰动的情况下,依然能够实现对直流微电网母线电压的稳定控制,具有较强的优越性和鲁棒性能。     

低开关频率下永磁同步电机弱磁区电流谐波抑制

针对内嵌式永磁同步电机在低开关频率下高速深度弱磁区电流畸变、转矩波动大等问题,分析了电机常规控制下系统对扰动信号的抑制作用;常规SVPWM过调制运行时会产生周期性扰动,结合试验及仿真数据,提出采用特定谐波消除SHEPWM调制抑制电流谐波的控制策略,改善了电机平稳运行能力。对所提出的优化脉冲模式进行Matlab仿真和试验验证,结果表明:采用特定谐波消除SHEPWM调制模式,可以有效抑制电机高速弱磁区的电流谐波,改善了系统稳态转矩控制效果。     

信号谐波分量失真度测量系统设计

针对一般测量系统的输入信号存在高次谐波的非线性失真现象,本设计以MSP430149单片机作为主控制器,在对输入信号进行前端处理之后,利用模拟乘法器解调的方式提取出输入信号中各谐波分量的幅度,并利用负反馈控制锁定调制信号的频率及相位;结合失真度的近似定义算法,实现非线性失真的指标计算并在上位机显示。相对传统的信号运算,利用DSP高速率芯片实现频谱分析的方法,采用模拟解调方式获取信号的相关信息,将输入信号的基波幅度和谐波幅度转化为直流信号,进而利用单片机片内ADC进行直流采样,可以大大降低对MCU的主频以及AD采样的速率要求,降低系统的开发成本。     

Active power filter using nonlinear repetitive controller

Active power filters as solutions to power quality problems have become more and more important nowadays. A nonlinear repetitive controller for current control of active power filters is proposed. The proposed method is composed of a repetitive controller and a deadband relay. Whenever the input error is above the threshold, the current control loop is driven dominantly by the deadband relay to obtain fast dynamic response. After the input error is below the threshold, the deadband relay automatically turns off and the repetitive control alone governs the current control to eliminate the steady-state error. Discussions on the design of the current and voltage control loops are also given. Simulation and experimental results verified the feasibility of the proposed method.     

A new error handling algorithm for controller area network in networked control system

An effective error handling mechanism plays an important role to ensure the reliability and robustness of the application of controller area network (CAN) in controlling dynamic systems. This paper addresses a new online error handling approach or named per-sample-error-counting (PSeC) technique that tends to replace native error handling protocol in controller area network (CAN). The mechanism is designed to manage transmission errors of both sensor and control data in networked control system (NCS) used in controlling dynamic system such that the stability of the feedback system is preserved. A new parameter denoted as maximum allowable number of error burst (MAEB) is introduced in which MAEB is selected based on available bandwidth of the CAN network. MAEB serves as the maximum number of attempt of re-transmission of erroneous data per sample which allows the maximum transmission period to be known and guaranteed for time-critical control system. The efficacy of the proposed method is verified by applying the algorithm on the fourth order inverted pendulum system simulated on Matlab/Truetime simulator and the performance is benchmarked with the existing CAN error management protocol. The simulation run under various systems conditions demonstrate that the proposed method results in superior system performance in handling data transmission error as well as meeting control system requirement.     

Multiple model adaptive control for a class of nonlinear systems with unknown control directions

This study introduces an improved multiple model adaptive control (MMAC) algorithm for a class of nonlinear discrete-time systems. The controller consists of a linear direct adaptive controller, a neural network-based nonlinear direct adaptive controller and a switching mechanism. The assumption of the nonlinear term is relaxed by incorporating a parameter estimator with an augmented error. The control direction of the system is not required to be known by employing a linear direct adaptive controller with the discrete Nussbaum gain and future output predictions. The stability of the closed-loop systems applying the proposed MMAC method is proved and the improved transient performance of the system is illustrated by the simulation results.     

无线网络化控制系统的功率感知事件触发策略及其闭环稳定性

本文研究了能量受限无线网络化控制系统的设计和分析问题.首先建立了无线网络化控制系统中通信传输时的数据误码率和丢包率间的定量关系,从而在通信功率与系统性能之间建立了联系.进而设计了基于事件触发策略和功率优化机制的智能控制器,该方法充分考虑了网络节能与控制系统性能表现两方面的要求,通过添加事件触发机制减少了系统的通信次数,并在此基础上以优化算法优化单次发送功率.随后,在随机稳定框架下给出了相应闭环系统稳定的充分性条件,在理论上证明了在该充分条件下,本文的设计能够在降低通信能耗的同时令系统维持预期的性能表现.最后数值例子证明了所提出方法的有效性.     

基于PR控制器的直接转矩控制策略研究

针对传统直接转矩控制中采用开关表控制造成转矩和电流脉动,以及传统调节器不能实现对交流输入信号的无静差控制等问题,基于电机空间电压矢量的转矩和磁链2个分量解耦的控制方式和PR控制器能够在静止坐标系下实现对交流输入信号的无静差控制,将PR控制器用于永磁同步电机的直接转矩控制中,并由此设计出磁链和转矩的双PR控制器。同时,在定子磁链的观测中,采用基于转子位置和定子电流的新型定子磁链估计方法。试验结果证明,将PR控制器对交流输入信号的无静差跟踪特性应用于基于空间电压矢量调制的直接转矩控制中,系统能获得优良的动态和静态响应,取得了显著的应用成效,由此验证了所提方法的正确性和可行性。     

Dynamic control of unified power flow controller under unbalanced network conditions

The effective and reliable use of existing transmission lines are critically important because high-voltage transmission networks met enormous power demands are very expensive investments in terms of their costs. Flexible Alternating Current Transmission Systems (FACTS) are quite efficient to control the power flow of the transmission lines and increase the current capacity of system. Unified Power Flow Controller (UPFC) is the more efficient among FACTS equipments which have the potential to increase the power flow and stability of the transmission line. This paper develops new control approaches for both series and shunt inverters of UPFC. The proposed controller algorithms of shunt and series inverters are based on fuzzy logic controller and rotating orthogonal-coordinate method, respectively. Dynamic control of power flow using proposed UPFC is analyzed as mathematically. Power System Computer-Aided Design (PSCAD) is used to simulate the system and test UPFC in the simulation environment. The test results are presented to show the increased stability of the system and improved dynamic response of UPFC during faults occurred in the transmission line.     

基于离散指数趋近律的开关电源模糊滑模控制

对于Buck/Boost变换器,传统的控制器如PID控制器、Ⅲ型误差放大器等存在超调量过大、响应时间过长、鲁棒性不强等问题,为克服这些缺点,提出基于离散指数趋近律的开关电源模糊滑模控制方案.首先,针对工作在电感电流连续模式(CCM)的Buck/Boost变换器采用状态空间平均法建立平均线性模型;然后设计离散指数趋近律的滑模控制器,并分析了切换参数对系统的影响;最后,为改善控制效果,设计了模糊控制器.仿真结果表明,相对于传统的控制器,指数趋近律的模糊滑模控制器有效地降低了超调量,提高了系统的响应时间,并且对外部干扰的鲁棒性较好.利用所设计的控制算法实现了对50 W高频开关电源样机的良好控制,进一步证明了所提方法的有效性.     

An Adaptive Wireless Power Sharing Control for Multiterminal HVDC

Power sharing among multiterminal high voltage direct current terminals (MT-HVDC) is mainly developed based on a priority or sequential manners, which uses to prevent the problem of overloading due to a predefined controller coefficient. Furthermore, fixed power sharing control also suffers from an inability to identify power availability at a rectification station. There is a need for a controller that ensures an efficient power sharing among the MT-HVDC terminals, prevents the possibility of overloading, and utilizes the available power sharing. A new adaptive wireless control for active power sharing among multiterminal (MT-HVDC) systems, including power availability and power management policy, is proposed in this paper. The proposed control strategy solves these issues and, this proposed controller strategy is a generic method that can be applied for unlimited number of converter stations. The rational of this proposed controller is to increase the system reliability by avoiding the necessity of fast communication links. The test system in this paper consists of four converter stations based on three phase-two AC voltage levels. The proposed control strategy for a multiterminal HVDC system is conducted in the power systems computer aided design/electromagnetic transient design and control (PSCAD/EMTDC) simulation environment. The simulation results significantly show the flexibility and usefulness of the proposed power sharing control provided by the new adaptive wireless method.     

Deep Learning-Based FOPID Controller for Cascaded DC-DC Converters

Smart grids and their technologies transform the traditional electric grids to assure safe, secure, cost-effective, and reliable power transmission. Non-linear phenomena in power systems, such as voltage collapse and oscillatory phenomena, can be investigated by chaos theory. Recently, renewable energy resources, such as wind turbines, and solar photovoltaic (PV) arrays, have been widely used for electric power generation. The design of the controller for the direct Current (DC) converter in a PV system is performed based on the linearized model at an appropriate operating point. However, these operating points are ever-changing in a PV system, and the design of the controller is usually accomplished based on a low irradiance level. This study designs a fractional-order proportional-integrated-derivative (FOPID) controller using deep learning (DL) with quasi-oppositional Archimedes Optimization algorithm (FOPID-QOAOA) for cascaded DC-DC converters in micro-grid applications. The presented FOPID-QOAOA model is designed to enhance the overall efficiency of the cascaded DC-DC boost converter. In addition, the proposed model develops a FOPID controller using a stacked sparse autoencoder (SSAE) model to regulate the converter output voltage. To tune the hyper-parameters related to the SSAE model, the QOAOA is derived by the including of the quasi-oppositional based learning (QOBL) with traditional AOA. Moreover, an objective function with the including of the integral of time multiplied by squared error (ITSE) is considered in this study. For validating the efficiency of the FOPID-QOAOA method, a sequence of simulations was performed under distinct aspects. A comparative study on cascaded buck and boost converters is carried out to authenticate the effectiveness and performance of the designed techniques.     

Hybrid Adaptive Type‐2 Fuzzy Tracking Control of Chaotic Oscillation Damping of Power Systems

In this paper a novel hybrid direct/indirect adaptive fuzzy neural network (FNN) moving sliding mode tracking controller for chaotic oscillation damping of power systems is developed. The proposed approach is established by providing a tradeoff between the indirect and direct FNN controllers. It is equipped with a novel moving sliding surface (MSS) to enhance the robustness of the controller against the present system uncertainties and unknown disturbances. The major contribution of the paper arises from the new simple tuning idea of the sliding surface slope and intercept of the MSS. This study is novel because the approach adopted tunes the sliding surface slope and intercept of MSS using two simple rules simultaneously. One advantage of the proposed approach is that the restriction of knowing the bounds of uncertainties is also removed due to the adaptive mechanism. Moreover, the stability of the control system is also presented. The proposed controller structure is successfully employed to damp the complicated chaotic oscillations of an interconnected power system, when such oscillations can be made by load perturbation of a power system working on its stability edges. Comparative simulation results are presented, which confirm that the proposed hybrid adaptive type‐2 fuzzy tracking controller shows superior tracking performance.