A Fully Distributed Voltage Optimization Method for Distribution Networks Considering Integer Constraints of Step Voltage Regulators

Abstract

With the increasing penetration of distributed photovoltaics (PVs), the operation and control of distribution networks (DNs), especially voltage control, have become more complicated. To deal with the voltage violation problem caused by large-scale PV access, this paper presents a fully distributed optimization method that combines the alternative direction multiplier method (ADMM) with the branch and bound method (BBM) for regional DNs. The total cost of active power losses and PV generation losses is minimized by making full use of the voltage regulation resources, e.g., reactive power compensators, step voltage regulators (SVR), and PV inverters, and the ADMM is employed to realize the intra-regional optimization and interregional coordination. To overcome the non-convex problem that is introduced by the SVR, the constraints of real-value tap positions are reformulated as linear inequality constraints of boundary voltages and added to the original problem, then the integer optimal solutions of SVR tap positions are obtained by BBM. The effectiveness of the proposed method is verified via numerical simulations on a practical 32-bus DN in China and a modified IEEE123-bus system. INDEX TERMS Active distribution networks, distributed optimization, voltage control, step voltage regulator.

Network Simplification-Based Cluster Coordinated Optimization Method for Distributed PVs With Inadequate Measurement

“…To sum up, the CAO model of C K includes (6)-(12), (14)- (15) and (19)- (20), which is a nonconvex NP problem. SOCP is applied to make it convex in this paper [19].…”

“…It is assumed that only the nodes with distributed PVs and SVCs have the real-time measurement facilities in this paper. In this case, the measurement nodes include node 3,4,7,11,13,15,17,18,19,23,25,27 and 29.…”

“…Since the optimal power flow (OPF) model is a nonconvex NP problem, the second order cone programming (SOCP), semidefinite relaxation and dc power flow approximation can be applied to make the optimization model convex [12]- [14]. For the distribution networks with massive distributed PVs, reactive power optimization sometimes cannot solve the voltage violation [15]. In [8], the distributed inter-cluster optimization is based on the joint active-reactive power optimization model, whose objective is minimizing the network losses and PVs generation losses.…”

Distributed Solution of Stochastic Volt/VAr Control in Radial Networks

“…However, both these proposed algorithms ignore the discrete controlling devices and are therefore only able to dispatch the optimal DG inverter reactive powers. Recently, researchers have attempted to include these discrete controlling devices with the ADMM based voltage optimisation strategies [19], [20]. The algorithm proposed in [19] uses the branch and bound method to estimate the tap positions of the LTCs in its ADMM based voltage optimization method.…”

“…Recently, researchers have attempted to include these discrete controlling devices with the ADMM based voltage optimisation strategies [19], [20]. The algorithm proposed in [19] uses the branch and bound method to estimate the tap positions of the LTCs in its ADMM based voltage optimization method. However, the LTC tap positions can be successfully estimated only if the LTCs are located on the boundary branches -which are shared between adjacent control areas.…”