Inverter VAR control for distribution systems with renewables

Abstract

Abstract-Motivated by the need to cope with rapid and random fluctuations of renewable generation, we presents a model that augments the traditional Volt/VAR control through switched controllers on a slow timescale with inverter control on a fast timescale. The optimization problem is generally nonconvex and therefore hard to solve. We propose a simple convex relaxation and prove that it is exact provided oversatisfaction of load is allowed. Hence Volt/VAR control over radial networks is efficiently solvable. Simulations of a real-world distribution circuit illustrates that the proposed inverter control achieves significant improvement over the IEEE 1547 standard in terms of power quality and power savings.

Optimal Allocation of Dispersed Energy Storage Systems in Active Distribution Networks for Energy Balance and Grid Support

“…A relaxation of the local load/ generation balance is proposed in [23], and it is proven to result into a convex problem. In [24], a sufficient condition is proposed for verification of the relaxed OPF problem exactness.…”

Extremum Seeking control of smart inverters for VAR compensation

“…These results were compared to a baseline case that was known a priori to produce optimal results [4].…”

“…3, that depicts feeder head reactive power in three cases: 1) a baseline case, 2) the simulation results of the ES controller, and 3) the result obtained from use of the techniques in [4] (i.e., the optimal results). This plot shows the reactive power that is supplied to the rest of the feeder by the distribution substation.…”

“…These equality constraints are nonlinear and, in general, nonconvex. The OPF problem can be transformed into a convex program through the use of convex relaxations, and a substantial body of work exists dealing with these issues [4], [6], [5]. However, such approaches are not well suited to the problem considered here, as the ES control algorithm is feedback-based and does not allow for the relaxation of the physics of the system.…”

“…The authors of [4] considered voltage regulation and loss minimization in distribution circuits using second order cone relaxations of balanced feeder models. The work in [5] and [6] have considered voltage regulation in distribution networks in the context of power flow through framing the decision process as a semidefinite program.…”