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双语推荐:三相四线制

通过分析三相四线制供配电系统中性线开断且三相负载不平衡时,产生过、欠电压的危害性,探讨住户装设过、欠电压保护电器的必要性。对三相供电住户采用单相或三相自恢复式过、欠电压保护电器的利弊进行分析、比较,指出住户三相供电存在的安全隐患,建议对自恢复式过、欠电压保护电器多加讨论。
Whe n the neutral line is cut off and the three-phase loads are unbalanced, a danger of overvoltage/undervoltage will occur, through the analysis of three-phase four-wire power supply and distribution system. Therefore, it is necessary for the households to install the overvoltage and undervoltage protective devices. The analysis and comparison of advantages and disadvantages of the single-phase or three-phase self-restoring overvoltage and undervoltage protective devices adopted by three-phase power supply households indicates that there are potential safety hazards for the three-phase power supply households. Further discussion on the self-restoring overvoltage and undervoltage protective devices is recommended.
三相电路功率的测量是三相电路分析的重要内容,按三相三线三相四线制分类,都有较详细的讨论,但针对三相三线电能表自身单相功耗测量仍未有一个很明确的说法。针对三相三线电能表从电源设计方案到三相电路的功率测量的不同方法进行分析,按照实际应用的场合需求和意义,分析三相三线电能表功耗的检定的具体方法。
The three-phase circuit power metering is an important content of three -phase circuit analysis , which has been discussed in detail with the classification of three -phase three-wire system and three -phase four -wire system.There is still not a explicit statement for the three -phase three-wire electric energy power meters ’ own sin-gle phase power consumption metering .The design strategy of power supply and the different methods of the three -phase circuit power metering have been analyzed .Finally, the specific verification methods for the power consumption of the three-phase three-wire electric energy power meter will be analyzed according to the actual application re-quirements and significance .

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通过对比分析三相四线制有源电力滤波器(APF)的两种拓扑结构的优缺点,选择了补偿效果更好的四桥臂拓扑结构。采用改进的ip-iq型检测算法对特指的次谐波进行检测,分次进行补偿,可以灵活选择补偿谐波的次数,以适应不同的工业现场的需要。仿真结果表明,设计的三相四线制二重化APF具有很好的谐波效果并能有效地抑中线电流。
Through contrasting and analyzing the advantages and disadvantages of two kinds of topologies of three-phase four-wire system active power filter (APF), the four legs topology structure with better compensation effect is chosen. Designated sub harmonics are checked by adopting the improved ip-iq type detection algorithm and gradation compensates. It can neatly select the number of compensating harmonics to suit the needs of different industrial application. The simulation results show that designed three-phase four wire system with dual APF has very good harmonic effect and can effectively inhibit neutral current.

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本文针对三相四线制配电系统中建立了三相不对称负荷的负序容量与负荷相间功率之间的函数关系,并建立了负载率与变压器效率的函数关系。通过理论分析与试验研究得出了三相不平衡度对变压器效率影响的关系。
This paper establishes the function relationship between three-phase asymmetric load''s negative sequence capacity and the load and power based on the three-phase four wire distribution system, and sets up a function of load rate and transformer efficiency. The relationship of the impact of the three-phase imbalance degree on the efficiency of the transformer is obtained by theoretical analysis and experimental study.

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介绍供配电专业部分技术名词与术语的基本涵义.包括三相三线三相四线制、接地与“接零”、一点接地与多点接地、零序电流与剩余电流、零序电压与剩余电压,结合在供配电专业电气设计中的应用进行分析。
The paper provides the basic connotation of certain technical terms and nomenclature in power supply and distribution discipline ( including three-phase three-line system & three-phase four-line system, earthing & neutral earthing, one-point earthing&multipoint earthing, zero-sequence current & residual current, and zero-sequence voltage &residual voltage), and analyzes in details based on practical application in electrical design for power supply and distribution discipline.
在高级量测体系环境下,为提高配网状态估计性能,提出一种三相四线制配网的抗差状态估计方法。该方法完全采用智能电表量测的实际三相电压电流幅值和功率实时量测,以三相四线制配网节点注入电流方程为基础,建立指数加权最小二乘抗差估计模型。模型中将零注入功率方程同时作为虚拟量测方程和等式约束,目标函数中采用标准化残差的指数型权函数,以改善状态估计的收敛性和抗差性;而且该模型不存在系统中性点电位均为零和电源端点三相电压对称且已知的假设条件。最后,IEEE13节点修正系统的仿真结果表明,提出模型方法的估计结果精度高,且具有良好的收敛性和抗差性。
With the development of advanced metering infrastructure (AMI), a new robust state estimation method for three-phase four-wire distribution system was proposed to improve the performance of state estimation in this paper. According to the actual three-phase voltage and current as well as power measurements in real-time from smart meters, the exponential weighted function least squares estimation model was proposed, which was based on the current injection equation in three-phase four-wire distribution network. With no assumptions of zero potential of neutral voltage and known three-phase voltage balanced in the substation, the proposed model could enhance the convergence and robustness performance of state estimation significantly by employing the exponential weighted function of standardized residual and handling zero-injection equations as virtual measurement equations and equality constraints. The simulation results for modified IEEE13 node test system have indicated that
三相四线制低压微网中,由于接入大量单相负荷,常引起三相不平衡情况。而传统控方法在三相不平衡情况下不能有效控低压微网在孤岛运行时的电压和频率稳定。针对三相四线制低压微网特点,设计了单相电压独立控的下垂控方法。论文首先在考虑低压微网的阻抗特性主要呈阻性的情况下,采用了改进的下垂控方法,并设计了单相电压独立控,使控系统能够运行在三相不平衡负荷下;然后设计两级控对低压微网孤岛运行时的频率和电压进行控,并对误差量进行修正;最后根据设计的控策略进行系统仿真分析验证方法有效性。在PSCAD平台上通过对搭建的小型低压微网算例仿真,验证了基于改进下垂控的单相独立控方法的有效性以及能够实现低压微网孤岛运行时电压频率稳定的要求,所设计的方法能够达到在三相不平衡情况下的控目标。
In the three-phase four-wire low-voltage microgrid, the large amount of single -phase load will always cause three-phase imbalance .In such situation , the traditional control method will not keep the voltage and frequen-cy stable effectively when operating in low -voltage microgrid in the island mode .According to the characteristics of the three-phase four-wire low-voltage microgrid , a single-phase independent control has been proposed based on the droop control.Firstly, considering the impedance characteristic of the low voltage microgird mainly appears as re-sistance , the improved droop control method is adopted , and a single-phase independent control strategy has been designed to ensure the normal operation of the control system under the unbalanced loads .Then a two-level control strategy has been proposed to control the voltage and frequency in the microgrid during the island mode .Finally, a simulation analysis based on the proposed method is used to prove the effe
为使三相四线制电网中谐波电流检测电路结构更为简单,响应速度更快,检测结果更为精确,基于瞬时无功功率理论,对传统谐波电流检测法进行改进。将锁相环PL L去掉,设定固定角速度构造正、余弦回路;提出新算法矩阵,改进 i p-iq算法,去掉零序分量,使得三相四线制电网中电流正序分量的计算更为简便;将低通滤波器L PF换成陷波滤波器,利用其点阻滤波的特性,滤除工频电流,然后与含有谐波的原电流作差,快速、精确测得谐波电流。通过仿真,验证了改进后的 i p-iq法检测电路更简单、响应更快、检测结果更精确。
To make the application of the harmonic current detection circuit structure to three-phase four-wire power system more simple ,the response faster and the test results more accu-rate ,the harmonic current detection method was improved on the basis of instantaneous reactive power theory .First ,we removed the phase-locked loop PLL ,and set a fixed angular velocity and structure of sine and cosine loop ;Second ,we improved the algorithm by proposing a new algo-rithm to remove the zero-sequence component , making the calculations of current positive se-quence component in three-phase four-wire power system easier ;Finally ,we replaced the low-pass filter LPF with notch filter ,filtered the current of 50 Hz frequence out using its point stop filter characteristics ,then compared with the current with harmonic arrent ,measuring the har-monic current quickly and accurately .The simulation proved that the improved detection method made the circuit simpler ,response faster and the test results

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针对传统三相四线制低压配电方式存在的线路损耗大等问题,提出单相配电系统的接入方式,以某城市居民小区为例,对2种配电方式的功率损耗和设备投资进行比较,认为单相配电系统可有效降低电网损耗,提高居民供电质量。
The traditional three-phase four-wire system in low voltage can cause large line loss .T his paper proposes the access mode of single-phase distribution system ,taking a real urban res-idential area case as an example ,this paper compares the power loss and equipment investment of power distribution mode of single-phase and three-phase respectively ,considers that the sin-gle-phase power distribution mode can effectively reduce the dis-tribution loss and enhance power supply quality .

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配电网中三相负载不对称,会导致三相电流电压不对称。基于瞬时对称分量法对三相电压和电流量进行分解,提出了一种新的正序、负序和零序电流直接控方法,应用于三相四线制配电网并联型D-STATCOM (配电网静止同步无功发生器)。正序电流控使D-STATCOM发出电网中需要补偿的无功电流和谐波电流;负序、零序电流由abc坐标系转换到 dq0同步旋转坐标系与期望值0做差进行控,用以补偿三相负荷不平衡。仿真结果表明,所提出的控方法可以使D-STATCOM有效补偿配电网三相负荷不平衡,提高配电网功率因数,同时消除非线性负荷引起的电流畸变。
The difference of three-phase load leads to the unbalance of three-phase voltage and current.Using the instantaneous symmetrical component method to decompose three-phase voltage and current, the paper proposes a new positive, negative and zero sequence direct current control method, which is mainly applied to the three-phase four-wire system that parallels D-STATCOM in the distribution network.The positive sequence current control is used to make the D -STATCOM generate reactive and harmonic current that needs to be compensated in the grid.Negative and zero sequence current is transformed from the abc coordinate system to the dq0 synchronous rotating coordinate system, and is subtracted with the expected value 0 to maintain the three -phase current bal-ance.Simulation results show that the proposed control strategy can effectively compensate the three-phase load un-balance and improve power factor at the line side, meanwhile eliminate current distortion caused by nonlinear l
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