Decentralized Voltage Control Strategy of Soft Open Points in Active Distribution Networks Based on Sensitivity Analysis

Abstract

With the increasing penetration of distributed generators, various operational problems, especially severe voltage violation, threaten the secure operation of active distribution networks. To effectively cope with the voltage fluctuations, novel controllable power electronic equipment represented by soft open points has been used in active distribution networks. Meanwhile, the communication has dramatically increased due to the rise of the variety and number of devices within the network. This paper proposes a decentralized voltage control method of soft open points based on voltage-to-power sensitivity. The method reduces the burden of communication, storage, and calculation effectively in a decentralized manner and fulfills the rapid requirements of large-scale active distribution networks. First, the network is divided into several sub-areas; each is under the control of one soft open point at most. The initial strategies of soft open points are adjusted by local voltage-to-power sensitivity and the voltage information within the sub-areas. If some nodal voltages still exceed the expected range after the sub-area autonomy, the operation strategies of soft open points are further improved by inter-area coordination with the alternating direction method of multipliers algorithm. The effectiveness of the proposed decentralized control method is verified on the IEEE 33-node system.

An Overview of Soft Open Points in Electricity Distribution Networks

“…To realize local control of SOPs, droop control methods are usually used [65]- [67]. In [66], an improved control strategy is further proposed to adjust the droop control coefficient in real time according to the rated active power and the value of active power variation.…”

Soft Open Point in Distribution Networks

“…In most of the cases the advantage of SOP to reduce the operational cost and power loss minimization is considered by considering the SOP efficiency. Most of the paper has considered the efficiency of SOP as 98% [45]- [46]. The efficiency of converters mostly depend on the operating load which is given in [47].…”

“…A decentralized control based on an alternating direction method of multipliers (ADMM) algorithm is proposed in [46] to improve the efficiency of the optimization calculation having the objective function as the minimization of voltage deviation in each sub-network. Decentralized control interprets to divide the DNs areas into sub-networks under local controllers.…”

Coordinated Voltage Regulation Methods in Active Distribution Networks with Soft Open Points

“…V 1 is the voltage of bus SOP,j ) denote the active power, reactive power and the active power loss at the i side (j side) of the SOP-ij, respectively. C ij SOP is the rated capacity of SOP-ij, and µ is the loss coefficient of SOPs, i.e., a factor for evaluating the active power loss of SOPs [29][30][31].…”

“…Therefore, this study converts these models into MISOCP model, where the objective functions and nonlinear constraints will be linearized. The MISOCP has been widely used in the planning and operation optimization of distribution networks, because it can quickly and effectively solve nonlinear programming problems [28][29][30][31]. In this work, constraints that need to be converted are:…”