无额外直流储能元件的串联型电能质量控制器新型控制策略

对电压幅度暂变的最大补偿时间是串联型电能质量控制器(series power quality controllers,SPQC)重要性能指标。若没有额外直流储能元件,传统的同相位控制或能量优化控制只能提供有限的补偿时间。该文对SPQC提出一种新型控制策略,它在负载电压控制的同时,自动地从电源吸收部分有功功率来补偿其系统损耗,从而提高最大可补偿时间;甚至在没有额外直流储能元件时还具有持续补偿能力。采用负载电流相量为参考相量的新型相量图表示方法,使得SPQC系统内各相关变量之间的关系更加清晰简单。在电源电压幅度暂变和额定状态,分别对系统进行相应的相量图分析,得到采用这种新型控制策略的定量补偿电压幅度、可完全补偿的最大程度电压暂低以及系统的功率流动方式。根据系统能量平衡关系,提出该新型控制策略的一种简单统一实现方法。计算机仿真和原型实验验证了所得结论。     

A method for designing the power and capacitance of fuel cells and electric double‐layer capacitors of hybrid railway vehicles

A hybrid railway traction system with fuel cells (FC) and electric double‐layer capacitors (EDLC) is discussed in this paper. This system can save FC costs and absorb regenerative energy. A method for designing FC and EDLC on the basis of the output power and capacitance, respectively, has not been reported, although their design is one of the most important technical issues encountered in the design of hybrid railway vehicles. Such a design method is presented along with a train load pro?le and an energy management strategy. The design results obtained using the proposed method are veri?ed by performing numerical simulations for a running train. These results reveal that the proposed method for designing the EDLC and FC on the basis of the capacitance and power, respectively, and using a method for controlling the EDLC voltage, is su?ciently e?ective in designing e?cient EDLC and FC of hybrid railway traction systems. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 184(3): 47–54, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22395     

Firefly Optimization Algorithm for the Reactive Power Control of an Isolated Wind-Diesel System

This paper investigates the application of firefly optimization algorithm to design an optimal control for voltage stability of a stand-alone hybrid renewable generation unit based on reactive power control. The studied renewable generation unit mainly consists of a permanent magnet induction generator driven by wind turbine and a synchronous generator driven by diesel engine. A STATCOM is used to stabilize the terminal load bus voltage via compensating of reactive power. The main control objective aims to stabilize the terminal load voltage against any disturbances in load reactive power and/or input wind power by adjusting the total system reactive power. This is accomplished by controlling STATCOM phase angle and hence to control the load bus voltage and also by controlling the excitation voltage of the synchronous generator. The proposed renewable energy power system based on the proposed optimal controller has been tested through step change in input wind power and load reactive power. The system performance based on the proposed control is compared with model predictive control, a robust H_∞ control, and a classical PI control.     

Compensation strategy of matrix converter fed induction motor drive under input voltage and load disturbances using internal model control

The Matrix Converter (MC) is well known for its diverse advantages and applications but the output characteristics are adversely affected by the input voltage disturbances because there is no energy storage elements present in the dc link. Hence the matrix converter fed drive performance is affected. In this paper, Internal Model Control (IMC) based controller which is capable of achieving perfect set point tracking and disturbance rejection is proposed for compensating the voltage disturbances and load disturbances of matrix converter fed vector controlled Induction Motor (IM) drives. Modeling of matrix converter with input voltage disturbances and parameter estimation of IMC based speed and current controllers for vector controlled induction motor drive are described in this paper. The simulation results validate the input voltage disturbance rejection and improved dynamic performance of matrix converter fed induction motor drive obtained using IMC based controller.     

Functional Predictive Control for Voltage Stability Improvements of Autonomous Hybrid Wind–Diesel Power System

This study investigates the application of the model predictive control technique for voltage stability of an isolated hybrid wind–diesel power system based on reactive power control. The proposed generation system mainly consists of a synchronous generator for a diesel-generator system and an induction generator for a wind energy conversion system. A static VAR compensator is used to stabilize load voltage through compensating reactive power. Two control paths are used to stabilize load bus voltage based on model predictive control. The first control path is used to adjust the total reactive power of the system by controlling the static VAR compensator firing angle. The second is proposed to control the excitation voltage of the synchronous generator. Model predictive control is used to determine t optimal control actions, including system constraints. To mitigate calculation effort and reduce numerical problems, especially in a large prediction horizon, an exponentially weighted functional model predictive control (F-model predictive control) is applied. The proposed controller was tested through step change in load reactive power plus step increase in input wind power. The performance of the proposed system with the proposed controller was compared with classical model predictive control; moreover, this scheme is tested against parameter variations.     

Double resonant tank LLC‐DCX based two‐stage power supply for magnetic levitation control system applications

Magnetic levitation train power supply systems, or Maglev, are most commonly powered by 330‐V high‐voltage direct current power systems. The power supply for maglev control system is used to provide a stable voltage to the suspension control circuit, which is the key part of Maglev trains. The suspension control power supply is typically a DC–DC converter with a high voltage input and multiple low voltage outputs. The traditional solutions typically lead to the following issues, such as uncontrolled duty ratio, poor cross‐regulation capability, and low reliability. In order to solve these problems, a novel two‐stage solution employing a double resonant tank LLC DC transformer (LLC‐DCX) is proposed and developed in this paper. The proposed solution not only increases the overall conversion efficiency significantly because of the achieved soft‐switching over the entire operation range, but also realizes the low input current ripple and high reliability owing to a uniform thermal distribution. A 210‐W, 220–380‐V input laboratory prototype with four outputs is fabricated and tested, and the experimental results are presented in this paper. The declared features of the proposed solution are well demonstrated by the experimental results. Copyright © 2015 John Wiley & Sons, Ltd.     

p-q-r理论在单相DVR中的应用研究

动态电压调节器是目前解决电压凹陷问题的较好选择,文章基于p-q-r理论,通过以单相电源作为参考电压构造虚拟三相系统及多次坐标变换,提出了一种在单相系统中实时检测电压凹陷并计算补偿电压的方法.电源侧电压的基波分量经过坐标变换后在p-q-r坐标下变为直流分量,在p-q-r坐标下控制器能快速计算出电压有效值和补偿电压,p-q-r坐标下的补偿电压经过反变换即可得到a- b-c坐标下各相的补偿电压.基于p-q-r理论的检测方法具有很好的静态和动态特性,仿真结果证明了该方法的正确性.     

Indirect current control of active filter for harmonic elimination with novel observer-based noise reduction scheme

Active power filters have been developed recently to solve the harmonics disturbance problems on power system networks. The direct current control scheme is generally used to control the harmonic compensating current directly for current source active power filters. To improve the characteristics of harmonic elimination, the voltage regulation scheme is proposed which regulates the filter capacitor voltage at the input side. Hence the voltage regulation scheme is an indirect current control technique for making sinusoidal line current. To implement this proposed scheme, the electronic differentiator should be used. By using the conventional differentiator, high frequency noise is generated in the controller. This deteriorates both the accuracy and reliability of the controller. To reduce this noise, a novel observer-based noise reduction scheme is proposed for our active filter system. The observer-based algorithm and characteristics of indirect current-controlled active filters are investigated through simulations and experiments.     

Comparison of Switching Loss of Single‐Phase Step‐Up/Step‐Down Bidirectional Converter with Voltage‐Fed/Current‐Fed Hybrid‐Type Operation

Electric energy storage systems are very important as one of the solutions to global warming. Step‐up/step‐down characteristics are required for electric energy storage systems. In addition, such systems must have high efficiency, low cost, and small scale. Therefore, the authors proposed a single‐phase step‐up/step‐down bidirectional converter with voltage‐fed and current‐fed hybrid‐type operation. The proposed converter consists of a two‐quadrant dc–dc converter and a single‐phase voltage‐fed converter. The circuit has several advantages such as low switching loss, use of very small capacitance, and so on. In this paper, the authors compare a comparison of the switching losses with a simple analysis.     

Experimental Verification of Photovoltaic-based Three-phase Four-wire Series Hybrid Active Power Filter

Abstract—This article proposes a photovoltaic and battery interfaced series hybrid active power filter, which is comprised of a series active power filter and an inductor-capacitor (LC) shunt passive filter. The main benefits of the proposed system provide the compensation against the voltage harmonics, current harmonics, and voltage interruption for the whole day. A series active power filter demands a source of energy for compensating the voltage sag/swell. The proposed topology utilizes the green energy source with an energy storage unit to meet the DC-link voltage requirement of the series active power filter. The control strategy is based on the dual formulation of the compensation system principles with adaptive fuzzy logic controller. The simulation and experimental studies are carried out to validate the effectiveness of the proposed photovoltaic interfaced three-phase four-wire series hybrid active power filter.     

A hybrid input charge‐pump using micropower thermoelectric generators

For industrial wireless transmitters, a hybrid input charge‐pump utilizing thermoelectric energy from waste heat is proposed in this paper. Unlike conventional converters, the proposed capacitor‐based converter supplies energy to a wireless transmitter by using a thermoelectric power source in combination with a rechargeable battery source. By combining the battery voltage and the thermoelectric generator (TEG) voltage, the proposed converter achieves a wider input range than conventional converters. Consequently, the proposed converter will enable the development of not only an industrial wireless transmitter but also various clean energy applications. Through theoretical analyses, simulations, and experiments, the following results are shown: 1. Even if the voltage of the TEG is small, the proposed converter can provide the sufficient voltage by compensating the insufficient voltage of the TEG with the battery voltage. 2. The formulas obtained by the theoretical analyses are useful for designing the proposed converter because the theoretical results correspond well with the simulation results. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Direct voltage regulation of DC–DC buck converter in a wide range of operation using adaptive input–output linearization

In this paper, an adaptive nonlinear controller is designed for voltage control of the DC–DC buck converter in both continuous and discontinuous conduction modes. The proposed controller is developed based on input–output linearization, which is robust and stable against converter load changes, input voltage variations, and parameter uncertainties. In the proposed approach, all the converter parameters, namely input voltage, load resistance, and other parasitic elements of the power circuit, are assumed to be uncertain and estimated using a suitable Lyapunov function. Using a stand‐alone TMS320F2810 digital signal processor from Texas Instruments, some simulations and experimental results are obtained to verify the proposed control approach. The results are in good agreement and prove the effectiveness and capability of the controller over a wide range of operations. Also, advantages of the designed nonlinear regulator are indicated in comparison with a pulse width modulation (PWM)‐based sliding mode controller. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Full-state Variables Control of a Grid-connected Pumped Storage Power Plant Using Non-linear Controllers

Abstract—In this article, a controller based on a multi-variable sliding mode is provided for pumped storage with four goals. (1) Full-state variables of the plant, generator, and hydro turbine are developed to improve transient responses under fault conditions by compensating the fast electrical dynamics. (2) The sliding-mode controller is designed for robustness against uncertainty in both the power system parameters and its topology. (3) Two surfaces (power angle and output voltage) are proposed to coordinate both the turbine and excitation inputs of the generator in transient conditions. (4) The decentralized method is used to decrease the complexity of the controller equations and cost of implementation. To show the effectiveness of the proposed controller, two other controllers—full-state variables feedback linearization and a generic power system stabilizer—are simulated by MATLAB/Simpower (The MathWorks, Natick, Massachusetts, USA). The simulation results show full-state variables feedback linearization cannot be robust against model uncertainty; it is also shown that the power plant with linear controller has unpleasant transient responses in both fault conditions and low-frequency oscillations. In contrast, the proposed method plays an effective role in solving the mentioned problems and limits the stator current magnitude and terminal voltage post-fault.     

Voltage Control Using PV Power Factor,Static Capacitor,and Transformer Tap for Large PV Penetration

The Japanese government has set 53 GW as the target level of PV deployment by 2030. However, the large‐scale introduction of PV will cause several problems in power systems. One of these problems is the increase in voltage due to decreased load demands associated with large PV active power output. Another problem is voltage variations caused by fluctuations in PV system output. In this paper, we focus our attention on the voltage and reactive power control for large‐scale PV deployment and propose voltage control using the PF (PV power factor), SC (static capacitor), and TAP (transformer tap). In the proposed method, the SC and TAP controls consider voltage stability through the use of VMPI‐i and VMPI‐i sensitivity, and the PF control suppresses voltage variation and voltage spikes. Finally, we simulate these controls using the Ward–Hale system to verify the validity of the proposed method.     

A Commutation Overlap Period Reduction Method Expanding the Buck Operating Range for a Bidirectional Isolated DC–DC Converter

This paper proposes a bidirectional isolated DC–DC converter with an active clamp circuit and two novel control methods in the buck mode. A circulating current reduction method decreases the conduction loss. A commutation overlap period reduction method maintains the output power by expanding the maximum actual duty cycle even if the input voltage decreases. The experimental results show that the proposed method increased the maximum output 1.5 times, without increasing the voltage applied to the low‐voltage side MOSFETs under the minimum input voltage condition. A 2‐kW class prototype showed a higher than 90% efficiency over a wide operating range for a greater than 20 input–output voltage ratio at 100‐kHz switching frequency.     

临界连续模式下高功率LED驱动电源谐振控制方法

针对传统LED驱动电源谐振控制方法电路控制谐波异常导致输出电流过冲、电压稳定控制效果差和时延高等问题,提出了临界连续模式下高功率LED驱动电源谐振控制方法。结合PFC和LLC半桥两种方式,控制LED驱动电源谐振部分的频率变化值,选取开关恒流源,选取FSFR2100集成控制芯片作为控制芯片。在临界连续模式下,计算高功率LED驱动电源电路中电感值、滤波电容,以此为参量依据,设定电路中的电压范围与最小开关频率、输出功率等,校正PFC电路控制谐波。以PFC控制器所计算的电流与电压数据为基础,计算谐振频率值,通过谐振网络部分调整电压增益,确保LED驱动电源开关管实现零电压开关,实现临界连续模式下高功率LED驱动电源谐振控制。实验结果表明,采用该方法进行谐振控制的LED驱动电源,工作效率和PF值分别保持在88%和0.99以上,并且开关损耗低,未出现电流过冲,输入电压与输出电流波形相同,整体控制效果较好。     

双电源故障无缝自愈配电环网潮流优化控制方法

在分析双电源故障无缝自愈配电环网供电系统的基础上,考虑网络有功损耗与节点电压偏差,提出了一种基于统一潮流控制器(UPFC)的配电环网潮流综合优化控制方法。分析了配电环网潮流最优分布规律,得出了网络有功损耗、负荷节点电压偏移与UPFC产生的串联补偿电压之间的内在关系。分别构建了网络有功损耗隶属函数与节点电压偏移隶属函数,用以表征各自偏移最优目标的程度;根据关注程度确定二者的权值进而得到了综合优化目标函数,最后通过全局最优化方法实现对串联补偿电压求解。建模仿真结果表明,该环网潮流综合优化控制方法能够均衡两侧出力,有效控制所有节点电压偏差与网络损耗,为故障无缝自愈技术的实现奠定基础。     

Adaptive nonlinear control of three-phase shunt active power filters with magnetic saturation

The problem of controlling three-phase shunt active power filters (SAPF) is addressed in presence of nonlinear loads. Previous works generally design control for SAPF based on standard models that assume the involved magnetic coil to be linear. In reality, the magnetic characteristics of these components are nonlinear (especially in the presence of large magnetic flux density in the ferromagnetic core). In this paper, a new oriented control model for SAPF-load system, taking into account for the nonlinearity of coil characteristics, is developed. The control objective is twofold: (i) compensating for the current harmonics and the reactive power absorbed by the nonlinear load; (ii) regulating the inverter DC capacitor voltage. To this end, based on the new model, a nonlinear controller is developed, using the backstepping technical design. It is therefore able to ensure good performances over a wide range of variation of the load current. Moreover, the controller is made adaptive for compensating the uncertainty on the switching loss power. The performances of the proposed adaptive controller are formally analyzed using tools from the Lyapunov stability and the averaging theory. The supremacy of the proposed controller with respect to standard control solutions is illustrated through simulation.     

Design of a dual‐input SC DC–DC converter realizing negative outputs

Aimed at a back‐lighting application, a dual‐input switched‐capacitor (SC) DC–DC converter with battery charge process is proposed in this paper. The proposed converter can realize −1/N× (N = 2,3,…) step‐down conversion as well as (N + 1)/N× step‐up conversion. By converting clean energy such as solar energy, the proposed dual‐input converter not only drives light‐emitting diodes (LEDs) but also recharges the battery, although conventional single‐input converter only consumes battery energy. In the proposed converter, the −1/N× stepped‐down voltage is generated to drive the LED's cathode when the input voltage is insufficient to drive a 1× transfer mode. Furthermore, unlike conventional converters, the battery is charged by the (N + 1)/N× stepped‐up voltage when the LED back light is in standby mode. Hence, the proposed converter can realize long battery run time. The validity of circuit design is confirmed by theoretical analyses, simulations, and experiments. The derived theoretical formulas will be helpful to estimate circuit characteristics, because the theoretical results correspond well with the simulation program with integrated circuit emphasis (SPICE) simulation results. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

适用于多端柔性直流电网的潮流控制器

多端柔性直流电网以优良的性能在清洁能源消纳方面发挥了重要作用,但其潮流难以灵活控制,需引入潮流控制器来改善潮流分布。对此,提出了一种适用于多端柔性直流电网的新型直流潮流控制器,其具有配置成本低、调节范围广和运行损耗小的优势。潮流控制器利用全控型开关动态投切电容、电阻来改变线路等效电阻,实现了潮流控制功能。此外,设计了含电压限制环节和电流差增益环节的控制系统,降低了拓扑的配置成本和运行损耗。最后,通过电磁暂态仿真与低压物理试验验证了所提直流潮流控制器的有效性与可行性。