Load compensation in four-wire electrical power systems

Oliveira, Luis Carlos Origa de; Neto, Mariano Castro; Souza, João Batista

doi:10.1109/icpst.2000.898206

Cited by 7 publications

(7 citation statements)

References 3 publications

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“…line-to-neutral voltages, currents , and consumed by the ZSCC compensator are broken down into a system of zero-sequence currents in the direction opposite to the zero-sequence currents of the load, and a balanced system of negative-sequence currents is created, whose values are obtained from Equation 15- (17); where − , − and − are the negative sequence currents consumed by the compensator in phases A, B and C, respectively. Substituting Equations (15)- (17) in Equations (12)- (14) and generalizing for z = {a, b, c}, Equation 18is obtained.…”

Section: Anmentioning

confidence: 99%

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Unbalanced and Reactive Currents Compensation in Three-Phase Four-Wire Sinusoidal Power Systems

et al. 2020

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In an unbalanced linear three-phase electrical system, there are inefficient powers that increase the apparent power supplied by the network, line losses, machine malfunctions, etc. These inefficiencies are mainly due to the use of unbalanced loads. Unlike a three-wire unbalanced system, a four-wire system has zero sequence currents that circulate through the neutral wire and can be compensated by means of compensation equipment, which prevents it from being delivered by the network. To design a compensator that works with unbalanced voltages, it is necessary to consider the interactions between it and the other compensators used to compensate for negative-sequence currents and positive-sequence reactive currents. In this paper, through passive compensation, a new method is proposed to develop the zero sequence current compensation equipment. The method does not require iteration algorithms and is valid for unbalanced voltages. In addition, the interactions between all compensators are analyzed, and the necessary modifications in the calculations are proposed to obtain a total compensation. To facilitate the application of the method and demonstrate its validity, a case study is developed from a three-phase linear four-wire system with unbalanced voltages and loads. The results obtained are compared with other compensation methods that also use passive elements.

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Section: Anmentioning

confidence: 99%

“…Considering Equations (15)- (17) and Equations (11)- (14), the neutral current I nW of the ZSCC compensator is determined by Equation (19) since I aW− + I bW− + I cW− = 0. This result is logical since the objective of the ZSCC compensator is to compensate for the neutral current consumed by the load.…”

Section: Anmentioning

confidence: 99%

Unbalanced and Reactive Currents Compensation in Three-Phase Four-Wire Sinusoidal Power Systems

et al. 2020

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“…where Q zF is the reactive power consumed by the NSCC compensator in all phases, and Q − zL+ is the reactive power caused by the positive-sequence voltage and negative-sequence current for any phase of the load. Substituting Equations (29) and (30) into (28), Equation (31) is obtained. It is observed that the power consumed by the compensator in one phase is equal to twice the reactive power caused by the negative-sequence current in the load in any phase with opposite sign.…”

Section: Negative-sequence Current Compensatormentioning

confidence: 99%

Compensation of Reactive Power and Unbalanced Power in Three-Phase Three-Wire Systems Connected to an Infinite Power Network

et al. 2019

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The compensation of an electrical system from passive compensators mainly focuses on linear systems where the consumption of charges does not vary significantly over time. In three-phase three-wire systems, when the network voltages are unbalanced, negative-sequence voltages and currents appear, which can significantly increase the total apparent power supplied by the network. This also increases the network losses. This paper presents a method for calculating the compensation of the positive-sequence reactive power and unbalanced powers caused by the negative-sequence line currents using reactive elements (coils and/or capacitors). The compensation is applied to three-phase three-wire linear systems with unbalanced voltages and loads, which are connected to an infinite power network. The method is independent of the load characteristics, where only the line-to-line voltages and line currents, at the point where compensation is desired, need to be known in advance. The solution obtained is optimal, and the system observed from the network behaves as one that only consumes the active power required by a load with a fully balanced current system. To understand the proposed method and demonstrate its validity, a case study of a three-phase three-wire linear system connected to an infinite power network with unbalanced voltages and currents is conducted.Appl. Sci. 2020, 10, 113 2 of 17 these inefficient powers. According to [13,14], imbalances at one point in the system can help offset some of the imbalances at another point. Such situations cannot be analyzed if only the modules of voltages and currents are known.The application of electronics, in the compensation of electrical systems, indicates that most industries today mainly focus on the use of active compensators. The advantages of these compensators or filters cannot be denied, especially for the compensation of non-linear systems. As compared to passive compensators, the active compensators are more expensive, less robust, and consume more energy. In certain situations, for linear systems, where the load does not vary with time, the use of passive compensators is a good alternative. They are configured from reactive elements (coils and/or capacitors). In this study, passive compensators are used to compensate for the reactive and unbalanced power resulting from the negative-sequence current of any three-wire system.The concept of compensation of an electrical system by passive compensators is not new. Steinmetz [15] developed a passive compensator to obtain a system of balanced line currents. He used a single-phase load with known data, and compensated it with a coil and capacitor and we believe that the voltages in the study were balanced. This study has been extended by many authors [16][17][18][19][20][21][22][23][24].Gyugyi et al.[25] studied compensation through passive compensators for a three-wire linear system with unbalanced load and balanced voltages. For this purpose, they categorised the line currents into symmetric component values, and proposed...

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“…Determination of the sequence components of the currents, on the phases of the load-Yn compensator-Δ compensator assembly seen from the network, is done based on the phase components of the currents [28]: As a result of the Adaptive Balancing Compensator (ABC) action, the load-compensator assembly is seen from the network as a perfectly balanced equivalent load, which consumes only active power [16,26,28]. For the sizing of the six susceptances of the compensator, the analytical expressions are determined applying the conditions of simultaneous cancellation of the symmetrical current components with negative effects on the phases of the load-compensator assembly: the imaginary (reactive) component of the positive sequence current, the real and imaginary components of the negative and zero sequence current components [9]:…”

Section: The "Classic" Methods Of Sizing a Balancing Reactive Compensatormentioning

confidence: 99%

From the Balancing Reactive Compensator to the Balancing Capacitive Compensator

2018

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Nowadays, improving the power quality at the Point of Common Coupling (PCC) between the consumers' installations and the distribution system operators' installations depends more and more on the use of specialized equipment, able to intervene in the network to eliminate or diminish the disturbances. The reactive power compensators remain valid solutions for applications in consumer and electricity distribution, in those situations when the criterion regarding the costs of installing and operating the equipment is more important than the ones related to the reaction speed or the control accuracy. This is also the case of the equipment for power factor improvement and load balancing in a three-phase distribution network. The two functions can be achieved simultaneously by using an unbalanced static var compensator, known as an adaptive balancing compensator, achieved by adjusting the equivalent parameters of circuits containing single-phase coils and capacitor banks. The paper presents the mathematical model for the sizing and operation of a balancing reactive compensator for a three-phase four-wire network and then presents some resizing methods to convert it into a balancing capacitive compensator, having the same functions. The mathematical model is then validated by a numerical application, modelling with a specialized software tool, and by experimental laboratory determinations. The paper contains strong arguments to support the idea that a balancing capacitive compensator becomes a very advantageous solution in many industrial applications.

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Load compensation in four-wire electrical power systems

Cited by 7 publications

References 3 publications

Unbalanced and Reactive Currents Compensation in Three-Phase Four-Wire Sinusoidal Power Systems

Unbalanced and Reactive Currents Compensation in Three-Phase Four-Wire Sinusoidal Power Systems

Compensation of Reactive Power and Unbalanced Power in Three-Phase Three-Wire Systems Connected to an Infinite Power Network

From the Balancing Reactive Compensator to the Balancing Capacitive Compensator

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