Three-Phase Power Imbalance Decomposition Into Systematic Imbalance and Random Imbalance

Kong, Wangwei; Ma, Kang; Wu, Qiuwei

doi:10.1109/tpwrs.2017.2751967

Cited by 23 publications

(6 citation statements)

References 23 publications

(37 reference statements)

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“…An example of phase unbalance with a definite direction is: phase a is heavier than the other two phases for 70% of the time and that phase a has an average current greater than that of the other phases. It is important to identify whether a phase unbalance direction exists or not, because the existence of the direction indicates that the loads are unevenly allocated towards a particular phase [68], meaning that offline load re-phasing is a feasible solution, e.g. move loads away from the consistent heavy phase to the other two phases during scheduled power cuts [68].…”

Section: Costly and Not Scalable To Millions Of LV Networkmentioning

confidence: 99%

“…It is important to identify whether a phase unbalance direction exists or not, because the existence of the direction indicates that the loads are unevenly allocated towards a particular phase [68], meaning that offline load re-phasing is a feasible solution, e.g. move loads away from the consistent heavy phase to the other two phases during scheduled power cuts [68]. However, not all cases have such a direction, e.g.…”

Section: Costly and Not Scalable To Millions Of LV Networkmentioning

confidence: 99%

See 1 more Smart Citation

Review of Distribution Network Phase Unbalance: Scale, Causes, Consequences, Solutions, and Future Research Direction

Ma¹,

Fang²,

Kong³

2020

Preprint

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Phase unbalance is widespread in the distribution networks in the UK, continental Europe, US, China, and other countries. First, this paper reviews the mass scale of phase unbalance and its causes and consequences. Three challenges arise from phase rebalancing: the scalability, data scarcity, and adaptability (towards changing unbalance over time) challenges. Solutions to address the challenges are: 1) using retrofit-able, maintenance-free, automatic solutions to overcome the scalability challenge; 2) using data analytics to overcome the data-scarcity challenge; and 3) using phase balancers or other online phase rebalancing solutions to overcome the adaptability challenge. This paper categorizes existing phase rebalancing solutions into three classes: 1) load/lateral re-phasing; 2) using phase balancers; 3) controlling energy storage, electric vehicles, distributed generation, and micro-grids for phase rebalancing. Their advantages and limitations are analyzed and ways to overcome the limitations are recommended. Finally, this paper suggests future research topics: 1) long-term forecast of phase unbalance; 2) whole-system analysis of the unbalance-induced costs; 3) phase unbalance diagnosis for data-scarce LV networks; 4) technocommercial solutions to exploit the flexibility from large threephase customers for phase balancing; 5) the optimal placement of phase balancers; 6) the transition from single-phase customers to three-phase customers.

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Section: Costly and Not Scalable To Millions Of LV Networkmentioning

confidence: 99%

Section: Costly and Not Scalable To Millions Of LV Networkmentioning

confidence: 99%

Review of Distribution Network Phase Unbalance: Scale, Causes, Consequences, Solutions, and Future Research Direction

Ma¹,

Fang²,

Kong³

2020

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…Therefore, the controller parameters constraint conditions can be described as: (1) In the parameters stability domain, the gain of the open loop system at the fundamental frequency is large.…”

Section: Design Of Controller Parametersmentioning

confidence: 99%

“…It has many advantages, such as high energy utilization and flexible and convenient use. With the complex and intelligent development of the power grid, the uneven distribution of the time-varying single-phase load has caused uneven distribution of the three-phase load, thus resulting in unbalanced three-phase current and extra neutral point current [1,2]. Unbalanced power has a great influence on the safe and stable operation of the distribution network system, causing additional losses of the line [3], increasing the losses of distribution transformers [4] and reducing the efficiency of motors [5].These will lead to the loss and waste of electric energy.…”

Section: Introductionmentioning

confidence: 99%

Zero-Axis Virtual Synchronous Coordinate Based Current Control Strategy for Grid-Connected Inverter

Yang¹,

Feng²,

Zhao³

et al. 2018

Energies

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Unbalanced power has a great influence on the safe and stable operation of the distribution network system. The static power compensator, which is essentially a grid-connected inverter, is an effective solution to the three-phase power imbalance problem. In order to solve the tracking error problem of zero-sequence AC current signals, a novel control strategy based on zero-axis virtual synchronous coordinates is proposed in this paper. By configuring the operation of filter transmission matrices, a specific orthogonal signal is obtained for zero-axis reconstruction. In addition, a controller design scheme based on this method is proposed. Compared with the traditional zero-axis direct control, this control strategy is equivalent to adding a frequency tuning module by the orthogonal signal generator. The control gain of an open loop system can be equivalently promoted through linear transformation. With its clear mathematical meaning, zero-sequence current control can be controlled with only a first-order linear controller. Through reasonable parameter design, zero steady-state error, fast response and strong stability can be achieved. Finally, the performance of the proposed control strategy is verified by both simulations and experiments.

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“…Three‐phase imbalance commonly happens in around 70% of the UK's low voltage (LV) power distribution networks [1, 2]. Financial losses are incurred due to wire losses such as losses in neutral wires [3] and additional network reinforcement investment such as equipment failure caused by network unbalanced operation [4].…”

Section: Introductionmentioning

confidence: 99%

New phase‐changing soft open point and impacts on optimising unbalanced power distribution networks

Lou

Yang

et al. 2020

IET Generation, Transmission & Distribution

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Three-phase unbalanced conditions in distribution networks are conventionally caused by load imbalance, asymmetrical fault conditions of transformers and impedances of three phases. The uneven integration of single-phase distributed generation (DG) worsens the imbalance situation. These unbalanced conditions result in financial losses, inefficient utilisation of assets and security risks to the network infrastructure. In this study, a phase-changing soft open point (PC-SOP) is proposed as a new way of connecting soft open points (SOPs) to balance the power flows among three phases by controlling active power and reactive power. Then an operational strategy based on PC-SOPs is presented for three-phase four-wire unbalanced systems. By optimising the regulation of SOPs, optimal energy storage systems dispatch and DG curtailment, the proposed strategy can reduce power losses and three-phase imbalance. Second-order cone programming (SOCP) relaxation is utilised to convert the original non-convex and non-linear model into an SOCP model which can be solved efficiently by commercial solvers. Case studies are conducted on a modified IEEE 34-node three-phase four-wire system and the IEEE 123node test feeder to verify the effectiveness, efficiency and scalability of the proposed PC-SOP concept and its operational strategy.MAX maximum active and maximum reactive powers of DER at node i at time t * conjugate transpose

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Three-Phase Power Imbalance Decomposition Into Systematic Imbalance and Random Imbalance

Cited by 23 publications

References 23 publications

Review of Distribution Network Phase Unbalance: Scale, Causes, Consequences, Solutions, and Future Research Direction

Review of Distribution Network Phase Unbalance: Scale, Causes, Consequences, Solutions, and Future Research Direction

Zero-Axis Virtual Synchronous Coordinate Based Current Control Strategy for Grid-Connected Inverter

New phase‐changing soft open point and impacts on optimising unbalanced power distribution networks

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