城市轨道交通供电系统谐波分布研究

针对城市轨道交通供电系统,对系统产生的谐波类型进行了分析,指出了谐波的危害性,分析了其特征,并详细分析了不同情况下注入系统节点的谐波大小的计算方法,特别是计算了35kV 系统和 110kV 系统在不同负荷状态下的特征次谐波的大小,并进行了实际的测量,建立系统谐波计算的分布图.对 110kV 侧的谐波电流进行了收集整理和研究,提出了降低谐波的方法和必要性.在此基础上,明确指出轨道交通供电系统应安装滤波装置或者有源滤波装置(APF),这不但可以大大地减小对电网的影响,也可以提高自身系统的运行质量和可靠性.     

基于巨磁阻的电力系统三相电流测量及其应用

在叙述了巨磁阻基本原理的基础上,提出了用巨磁阻传感器测量电力系统三相电流的原理和方法,解决了三相电流磁场相互干扰情况下三相电流的测量问题。     

有源电力滤波器在电铁谐波抑制中的应用与仿真

对应用于补偿电铁谐波的有源电力滤波器的性能进行了分析,并讨论了其工作原理。采用基于鉴相原理的检测法检测出待补偿电流的指令值,并利用单周控制的双向互补控制策略,使逆变器产生出补偿电流,来抵消电铁谐波源对电力系统带来的不利影响。同时在MATLAB/SIMULINK的仿真软件下,建立了电铁牵引供电系统,利用有源电力滤波器进行谐波抑制的仿真,仿真结果验证了该方案的正确性和可行性。     

Operations of the dominant harmonic active filter (DHAF) underrealistic utility conditions

This paper presents laboratory test results of the dominant harmonic active filter (DHAF) prototype. The DHAF system achieves harmonic isolation at the dominant harmonics using square-wave active filter inverters. The key advantages of the DHAF system are the low rating and low bandwidth requirements of the active filter inverter. Such characteristics allow cost-effective and viable applications of the DHAF system to mitigate harmonic problems for high-power nonlinear loads (10-100 MW and above). Several practical situations, including source-sink resonance, ambient harmonic interferences, and unbalanced grid voltages are applied to the DHAF prototype to validate its performance. The operation principles of the DHAF system and the synchronous-reference-frame-based controller are discussed to explain how harmonic isolation at the dominant harmonics is accomplished. A design example of the DHAF system for a 20 MVA rectifier load at an industrial site is also given to illustrate its application     

A DSP based power factor correction converter to reduce total harmonic distortion of input current for improvement of power quality

This paper proposes a controlled approach to be used in power factor correction (PFC) circuits to decrease total harmonic distortion (THD) of input current by eliminating the input current harmonics. This method removes the problems of the conventional PFC converters. Since in conventional PFC circuits the input current is controlled to follow the ac input voltage, it will have the same harmonics of the input voltage. This is an important disadvantage of the conventional method especially when the input voltage is distorted. In this approach, a sinusoidal signal is generated by the DSP microprocessor and is used as reference in controlling the converter switch to obtain a sinusoidal input current based on zero crossing points of distorted input voltage. Due to the reflection of input voltage distortions to the output voltage, an adaptive digital FIR filter is designed and embedded into the voltage control loop. The feed forward is also used into the control algorithm. The implementation of feed forward and adaptive digital FIR filter improves the converter performance to obtain a near unity power factor correction with lower input current THD. Average current control mode is implemented and operated in continuous conduction mode. The experiments performed in the laboratory for different cases of operation verify the theoretical and simulation studies performed in MATLAB/Simulink. The control approach is programmed by the TMS320F2812 DSP microprocessor. The experimental results are good in accordance with IEC 61000-3-2 Current Harmonic Standard.     

Investigation of harmonic currents and power factor on power rectifier circuits with nonequi-PWM and equi-PWM control (inductive load)

Lately, on the power rectifier circuit with semiconductor switching device, PWM control is generally employed for the purposes of reducing the harmonic currents on the dc side and improving the power factor of fundamental wave. In this case, the analysis of the current waveform becomes fairly complex. However, we express the PWM controlled voltage waveform by the step function, and can easily analyze the current waveform. We reported formerly some results of analysis about the waveform and harmonics of the current. In this paper, on the power rectifier circuit to which the nonequi-PWM and equi-PWM control are applied, we exactly calculate the harmonic currents on the dc and ac side, and the power factor by the use of the above analytical results. The characteristics of both control methods are compared on condition that each controlled factor of the load voltage is equal. These results are shown in the calculated charts. The following items can be seen from these charts on the power rectifier circuit: (1) The nonequi-PWM control can let the harmonic currents on the dc side decrease more than the equi-PWM control. But on the contrary, the harmonic currents on the ac side increase. Consequently, when the nonequi-PWM control is applied, the total power factor decreases by the increase of distortion factor of the current on the ac side. (2) The difference between the harmonic currents on the dc and ac side to both of the nonequi-PWM and equi-PWM control increases with the increase of controlled factor of the load voltage. © 1999 Scripta Technica, Electr Eng Jpn, 129(4): 117–125, 1999     

方波型逆变器总谐波失真度(THD)与其负载Q值的关系

对于方波型逆变器,总谐波失真度（THD）不仅仅随占空比变化,而且受负载类型的影响。本文在定义了一个反映负载特性的参数Q之后,报告了对THD与Q的变化关系的分析结果。     

Current waveform control of a high‐power‐factor rectifier circuit for harmonic suppression of voltage and current in a distribution system

This paper presents the input current waveform control of the rectifier circuit which realizes simultaneously the high input power factor and the harmonics suppression of the receiving‐end voltage and the source current under the distorted receiving‐end voltage. The proposed input current waveform includes the harmonic components which are in phase with the receiving‐end voltage harmonics. The control parameter in the proposed waveform is designed by examining the characteristics of both the harmonic suppression effect in the distribution system and the input power factor of the rectifier circuit. The effectiveness of the proposed current waveform has been confirmed experimentally. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 140(4): 62–71, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10046     

New adaptive reclosing technique using second-order difference of THD in distribution system with BESS used as uninterruptible power supply

This paper proposes a new adaptive reclosing technique that considers the battery energy storage system (BESS) in a distribution system. The proposed technique focuses on operation of the BESS as an uninterruptible power supply (UPS). The algorithm detects the fault clearance using second-order differences of total harmonic distortion (THD) (SODT) of the current supplied by the BESS and allows the BESS to keep feeding to the healthy phase. A synchronism check is adopted between the utility and the BESS to minimize the transients at the moment of reclosing. To verify the proposed algorithm, the whole system and algorithm were modeled using ATP-EMTP. Various simulations are performed by varying the fault clearance time, fault types, fault resistances, and fault locations. The simulation results show that the BESS can be operated as a UPS and provide an improved reclosing scheme.     

The Electromagnetic Transients Program (EMTP) as an effective tool to evaluate active power filters for harmonic compensation

The Institute of Electrical and Electronic Engineers (IEEE) ‘Recommended Practices and Requirements for Harmonic Control in Electric Power Systems’ sets limits for the current and voltage harmonic distortions at the point of common coupling in order to maintain an acceptable quality of electric power in the presence of nonlinear loads. Both the utility and its customers share a common responsibility since enforcement of the above practice by the utility would require that the affected customer use a suitable harmonic mitigating method. To this effect, this paper demonstrates how the Electromagnetic Transients Program (EMTP) may be used to investigate two harmonic mitigating methods, namely, the use of shunt passive power filters and the combination of a series active (APF) and shunt passive (PPF) power filters. Both methods reduce the harmonic currents injected into the distribution system; however, the combination of the series APF and shunt PPFs has a better compensation characteristic with a higher capital cost than only shunt PPFs. Before a final decision is reached, the cost of the higher harmonic losses throughout the distribution system when using only shunt PPFs must be taken into account.     

An approach to harmonic current-free AC/DC power conversion forlarge industrial loads: the integration of a series active filter with adouble-series diode rectifier

This paper proposes a new harmonic current-free AC/DC power conversion system characterized by the integration of a small-rated series active filter, with a large-rated double-series diode rectifier. The DC terminals of the active filter are directly connected in parallel with those of the diode rectifier, thereby forming a common DC bus. The active filter enables the diode rectifier to draw three-phase sinusoidal currents from the utility. In addition, it can provide the supplementary value-added function of regulating the common DC-bus voltage to a limited extent of ±5%, slightly increasing the RMS voltage rating, but not increasing the peak voltage rating. Experimental results obtained from a 5 kW laboratory system verify the practical viability and cost effectiveness of the proposed system     

Using the DC-bus current to improve the power factor in low-cost electric drives

In this paper, a new approach is presented aimed at improving the power factor of pulsewidth-modulation inverters that equip low-power electric motor drives for household appliances. The key feature of the proposed approach consists of exploiting the dc-bus current as a suitable dither generator by means of a high-frequency transformer. Such a strategy is used to force the diode rectifier to draw current from the mains in those periods when, in conventional systems, the diodes are reverse biased, i.e., when the dc-bus capacitor voltage exceeds the ac input voltage. The proposed method allows for elimination of the power-factor controller (PFC) front end, traditionally used to comply with power quality requirements. In comparison with standard PFCs based on a dc/dc converter, the proposed approach represents a cheaper and more feasible solution, not using additional power devices and control circuits. Simulation and experimental results confirm the consistency of the proposed approach.     

用MATLAB对电网谐波信号检测及谐波补偿进行仿真

依据三相电路的瞬时无功功率理论,推导了谐波电流的计算方法;用MATLAB为仿真工具,介绍谐波源构造、谐波检测、谐波分析及谐波抑制的仿真过程。     

配电自动化系统中的数据库管理系统解决方法

结合配电自动化工作中的一些开发经验,借鉴DA-2000配电自动化系统,针对配电自动化系统中的数据库管理系统的开发提出了有效的设计思路和方法。     

基于INT51X1芯片的调制技术在10kV配电网自动化通信系统中的应用

在10kV电力线上实现高速数据传输有着广阔的应用前景和经济价值，但是由于电力线信道存在着不可预期的高噪声、多径效应和信道衰落，严重制约了高速数据的传输。而近几年兴起的无线信道上实现高速数据传输的新技术，即OFDM(多载波正交频分复用)技术，是解决这些电力线通信问题的有效方法，文中提出了一种基于美国Intellon公司的INT51X1电力通信专用芯片并结合台湾Winbond公司32位ARM7TDMI内核的RISC微处理器W90N740的PLC通信系统的设计。     

双馈风电机组实现谐波可控的新方法研究

笼型异步电机用作风力发电机,其转子由两个“背靠背”连接的电压型PWM变换器进行励磁.当发电机工作在不同的同步旋转速度下时,网侧变换器便处在整流、逆变等不同状态,能量可以双向流动.对网侧变换器的有效控制,其实是对输入电流武功分量的控制,目的是实现直流母线电压恒定、网侧功率因数为1以及保证输入电流波形对称正弦等效果,进一步使风力发电机组的无功调节更加灵活,谐波含量明显减少.由于常规电流状态反馈PI控制效果受电机参数的影响比较大,提出了复数PI解耦控制,控制效果不依赖任何参数影响并且在保证稳定性的前提下大大减少了系统的谐波.     

A new approach to harmonic compensation in power systems-a combinedsystem of shunt passive and series active filters

A novel approach to compensating for harmonics in power systems is presented. It is a combined system of a shunt passive filter and a small rated series active filter. The compensation principle is described, and some filtering characteristics are discussed in detail. Excellent practicability and validity to compensate for harmonics in power systems are demonstrated experimentally. Although the source harmonic voltage was only 1%, the source harmonic current reached about 10% before the series active filter was started. After it was started, no harmonic current flowed into the shunt passive filter. In addition, no harmonic voltage appeared at the terminals of the shunt passive filter, because the source harmonic voltage was applied to the series active filter. The total loss of the series active filter was less than 40 W. It is concluded that the combined system is far superior in efficiency to conventional shunt active filters     

相间功率控制器(IPC)在电力系统中的应用

发展迅速的柔性交流输电及其控制器技术(FACTS)已被国内外普遍认为是新型有效的输电技术。除了其技术概念和技术规范取得新进展外,控制器技术也在快速发展着。其中的相间功率控制器IPC(Interphase Power Controller)能有效地控制线路潮流,提高线路输送功率或用于设备增容,限制短路电流。从IPC的基本原理和结构出发,研究了IPC的主要系统应用及在国外的研究和应用情况,IPC在未来互联电网中的可能工程布点,着重对IPC在联网中的可能应用进行了研究,并得出初步的结论。