Unbalanced Voltage Compensation with Optimal Voltage Controlled Regulators and Load Ratio Control Transformer

Abstract

Penetration of equipment such as photovoltaic power generations (PV), heat pump water heaters (HP), and electric vehicles (EV) introduces voltage unbalance issues in distribution systems. Controlling PV and energy storage system (ESS) outputs or coordinated EV charging are investigated for voltage unbalance compensation. However, some issues exist, such as dependency on installed capacity and fairness among consumers. Therefore, the ideal way to mitigate unbalanced voltages is to use grid-side equipment mainly. This paper proposes a voltage unbalance compensation based on optimal tap operation scheduling of three-phase individual controlled step voltage regulators (3φSVR) and load ratio control transformer (LRT). In the formulation of the optimization problem, multiple voltage unbalance metrics are comprehensively included. In addition, voltage deviations, network losses, and coordinated tap operations, which are typical issues in distribution systems, are considered. In order to investigate the mutual influence among voltage unbalance and other typical issues, various optimization problems are formulated, and then they are compared by numerical simulations. The results show that the proper operation of 3φSVRs and LRT effectively mitigates voltage unbalance. Furthermore, the results also show that voltage unbalances and other typical issues can be improved simultaneously with appropriate formulations.

Optimal Individual Phase Voltage Regulation Strategies in Active Distribution Networks with High PV Penetration Using the Sparrow Search Algorithm

“…The objective functions f it 7 , f it 8 , and f it 6 are integrated to obtain the comprehensive optimal operation in DNs. The f it 6 function is also normalized by dividing by its best solution, f it 6 best , which is 16, as solved above. Thus, the new objective function f it 9 is expressed as Equation (16).…”

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An Overview on Power Quality Issues and Control Strategies for Distribution Networks With the Presence of Distributed Generation Resources

“…One of the most widely used is the dynamic voltage regulator and static series compensator. The dynamic voltage regulator injects compensatory voltages through series connection transformers [51], [52]. In [53], the proposed method based on distributed source control is presented as a negative sequence conductor to compensate for voltage unbalance in the microgrid.…”

Analysis of Traditional and Alternative Methods for Solving Voltage Problems in Low Voltage Grids: An Estonian Case Study

“…For example, most residential electricity consumers are single-phase loads contributing to the voltage unbalance phenomenon that is always present, to some extent, in low voltage distribution networks. Single-phase photovoltaics, residential battery energy storage, and home electric vehicle charging stations [16][17][18] could further increase the voltage unbalance in the network. With the rapid changes imposed by stochastic charging activities, such a trend inevitably increases the difficulty of keeping an acceptable voltage profile in the distribution systems [19].…”