统一电能质量控制器的研究

该文讨论了统一电能质量控制器在d-q旋转坐标系下的解析模型。考虑到降低并联测有源滤波器的容量和成本问题,提出了混合式的并联结构单元。分别对UPQC的子电路和完整的UPQC系统在d-q旋转坐标系下建立了控制框图,最后给出了仿真和试验结果。     

农网配电台区电能质量现状分析及智能综合治理技术

随着社会的发展,农村的配电网在当今的社会环境中取得了比较广泛的应用,可以说是我国目前新农村建设非常重要的条件,配电网的质量直接影响了农村今后的发展方向与发展水平。随着我国对于农村的发展越来越重视,想要使用城乡一体化的发展模式提高农村的经济发展,但是农村配电网的发展也暴露出了很多的问题。于是我国开始大力对农村配电网进行整治,以此来达到解决农村配电网的质量问题,保证各家各户都能够安全用电。建设七稳定安全、技术先进、环保的农村配电网。本文基于此,首先对农村配电台区电能质量的现状进行了分析,最后通过应用智能综合治理技术的应用,为农村配电网的质量提升得到进一步的保证。     

烟草行业电能质量问题的监测与改善

通过使用有源滤波器谐波质量设备,并配合使用高级电能质量管理装置,实现了非线性负载设备的监测、分析与电能质量改善。所以,电能质量需要多维度、多个指标综合才能评判,本文主要论述电能质量的指标体系、监测法以及目前较为常用的电能质量改善技术的应用,如有源滤波器等。     

电能质量问题及谐波对电能计量的影响

1电能质量问题综述 近年来,随着以电力电子装置为代表的非线性负载的大量使用,以微机化为代表的各种复杂精密用电设备不断普及,用户对电能质量的要求不断提高。这一问题已引起各级电力部门的高度重视,国家也颁布了有关的技术标准。合格电能质量是指提供给敏感设备的电力和为其设置的接地系统均适合于该设备正常工作。     

如何测试诊断工业企业的电能质量问题

随着工业企业和商业用户用电设备的不断更新,对供配电系统的电能质量提出了更高的要求。同时各种各样的电能质量问题现在也层出不穷,如何来诊断这些问题是现场工程师必须具备的技能。本文通过两个工业电能质量案例,特别分析了三相不平衡、电压骤降等最常见的问题,说明一些电能质量问题诊断的步骤技能。     

供配电系统电能质量问题及其改善措施

在供配电系统中会出现谐波、供电频率误差、电压波动所造成的闪变等等一些问题,这些都会降低电能质量,对电力设备的使用寿命有巨大的损害。本文阐明了供配电系统电能质量问题、电能质量的好差标准及电能质量问题的改善方法与措施方案。     

低压配电网电能质量综合治理装置的设计

低压配电网电能质量综合治理装置用于解决低压配电网谐波严重、电压波动大等电能质量问题,具备零序滤波、无功补偿、二次防雷以及电能质量监测等功能。本文描述了低压配电网电能质量综合治理装置的设计思路与应用的技术,装置采用一体化设计,紧凑、实用、可靠。     

随时随地的电能质量专家

现代电力系统中用电负荷结构发生了重大变化：诸如半导体整流器，晶闸管调压及变频调整装置，炼钢电弧炉，电气化铁路和家用电器等负荷的迅速发展。由于其非线隐冲击性以及不平衡的用电特性使得电压的波形发生畸变，或是引起电压波动和闪变以及三相不平衡，甚至系统频率波动等。因此我们的结论是这些负荷是造成电自邑质量不佳的主要因素，而不好的电网又造成电力电子设备的不良运转，进     

工业电能质量问题的诊断

本文通过对一些工业电气扰动的分析，特别分析了暂态冲击，电压骤降这个最常见的问题，来说明一些电能质量问题诊断的步骤技能。     

A grid-interfacing power quality compensator for three-phase three-wire microgrid applications

This paper proposes a grid-interfacing power quality compensator for three-phase three-wire microgrid applications with consideration of both the power quality of the microgrid and the quality of currents flowing between the microgrid and utility system. It is proposed that two inverters connected in shunt and series are used for each distributed generation (DG) system in the microgrid. In each inverter, both positive- and negative-sequence components are controlled to compensate for the effects caused by the unbalanced utility grid voltages. Specifically, the shunt inverter is controlled to ensure balanced voltages within the microgrid and to regulate power dispatches among parallel-connected DG systems, while the series inverter balances the line currents by injecting appropriate voltage components. A current-limiting algorithm is also proposed and integrated within the inverter control schemes to protect the microgrid from large fault currents during utility voltage sags. The proposed compensator has been tested in simulations and experimentally using a laboratory hardware prototype.     

Apparent power transducer for three-phase three-wire system

In a newly developed transducer apparent power is measured by using a multiplier, in which the AC component of the output is used. For a three-phase three-wire system, two multipliers are used according to the so-called `two wattmeter' method. The AC output components are +30° and -30° phase-shifted, respectively, and then the difference is converted to a DC signal which corresponds to the total apparent power     

新型三相三线制并联有源滤波器的滑模控制方法

为了提高有源滤波器的谐波补偿效果,设计了一种新型滑模控制器,用于三相三线制并联有源滤波器的参考电流跟踪控制.谐波电流检测方法采用基于瞬时无功功率理论的谐波电流检测方法,能快速、准确的检测出负载电流中的谐波分量.直流侧电压控制方法采用PI控制方法实现.Simulink仿真结果显示,与传统的滞环比较控制方法相比,所设计的新型滑模控制方法能够有效的降低跟踪误差,提高有源滤波器的谐波补偿效果.     

A review of three-phase improved power quality AC-DC converters

Three-phase AC-DC converters have been developed to a matured level with improved power quality in terms of power-factor correction, reduced total harmonic distortion at input AC mains, and regulated DC output in buck, boost, buck-boost, multilevel, and multipulse modes with unidirectional and bidirectional power flow. This paper presents an exhaustive review of three-phase improved power quality AC-DC converters (IPQCs) configurations, control strategies, selection of components, comparative factors, recent trends, their suitability, and selection for specific applications. It is aimed at presenting a state of the art on the IPQC technology to researchers, designers, and application engineers dealing with three-phase AC-DC converters. A classified list of around 450 research articles on IPQCs is also appended for a quick reference.     

Application of a three-level NPC inverter as a three-phase four-wire power quality compensator by generalized 3DSVM

A two-level four-leg inverter has been developed for the three-phase four-wire power quality compensators. When it is applied to medium and large capacity compensators, the voltage stress across each switch is so high that the corresponding dv/dt causes large electromagnetic interference. The multilevel voltage source inverter topologies are good substitutes, since they can reduce voltage stress and improves output harmonic contents. The existing three-level neutral point clamped (NPC) inverter in three-phase three-wire systems can be used in three-phase four-wire systems also, because the split dc capacitors provide a neutral connection. This paper presents a comparison study between the three-level four-leg NPC inverter and the three-level NPC inverter. A fast and generalized applicable three-dimensional space vector modulation (3DSVM) is proposed for controlling a three-level NPC inverter in a three-phase four-wire system. The zero-sequence component of each vector is considered in order to implement the neutral current compensation. Both simulation and experimental results are given to show the effectiveness of the proposed 3DSVM control strategy. Comparisons between the 3DSVM and the 3-D hysteresis control strategy are also achieved.     

Resonant-boost-input three-phase power factor corrector

This paper presents a novel three-phase power factor corrector (PFC) circuit which uses two power switches working in zero-voltage-switching (ZVS) condition. The two switches along with a high-frequency inductor constitute a high-frequency current source which is responsible for the energy transfer in the circuit. The input current is partly continuous and partly discontinuous. The total harmonic distortion (THD) in the input current has a low value of 4.5%, and the output DC voltage is very close to the peak line voltage. The operation of the converter is explained by identifying the different switching modes, and the simulation and experimental waveforms are presented     

Instantaneous power compensation in three-phase systems by using p-q-r theory

This paper proposes a novel power compensation algorithm in three-phase four-wire systems by using p-q-r theory. The p-q-r theory is compared with two previous instantaneous power theories, p-q theory and cross vector theory. The p-q-r theory provides two-degrees of freedom to control the system currents by only compensating the instantaneous imaginary power without using any energy storage element. The definition of powers maintains power conservation, and agrees well with the general understanding of power. Simulation results show the superiority of p-q-r theory both in definition and compensation.     

Single-phase to three-phase power conversion interface

This study proposes a single-phase to three-phase power conversion interface which converts the power from a single-phase utility to three-phase power for a three-phase load. The proposed single-phase to three-phase power conversion interface comprises a bridge-type switch set, a set of three-phase inductors, a transformer set and a set of three-phase capacitors. A current-mode control controls the switching of bridge-type switch set, to generate a set of nonzero-sequence (NZS) currents and a set of zero-sequence (ZS) currents. The transformer set is used to decouple the NZS currents and the ZS currents. The NZS currents are used to generate a high-quality three-phase voltage that supplies power to a three-phase load. The ZS currents flow to the single-phase utility so that the utility current is sinusoidal and in phase with the utility voltage. Accordingly, only a bridge-type switch set is used in the single-phase to three-phase power conversion interface to simply the power circuit. A prototype is developed and tested to verify the performance of the proposed single-phase to three-phase power conversion interface.     

具有高功率密度的三相AC-DC 48V电源

在电力系统的电源质量国际标准规定中,电网连接设备的线电流谐波要低于门限值;因此,要求AC-DC变流器运行时要具有高功率因数和低线电流失真。本文实现了一种用于电源系统的三相AC-DC48V电力电子变流器,并进行了相关的实验测试与讨论。在电源设计上的主要限制条件是要求功率密度达到每立方分米9000W,同时供电线路中不用中性线。     

A new unified approach to power quality management

A new control algorithm for a power converter-based device that is capable of alleviating the problems of harmonic interference and voltage regulation on radial distribution lines is introduced. It comprises a relocatable converter in series with a passive filter and is known as the Power Quality Manager. Simulation results based on an existing 88-kV line are presented. Experimental results are presented, based on a three-phase 200-VA scaled model of the existing 88-kV system. It is a cost-effective and flexible solution to improving power quality