Unbalanced Modelling of STATCOM and SVC in Hybrid Load Flow Method

Abstract

Modern power distribution systems are installed with a number of distributed power generation in the presence of Flexible AC Transmission System (FACTS) devices. Increased integration of distributed power generation makes the distribution system vulnerable to unbalanced operating conditions, meaning it would then require the support of FACTS for a smooth operation of the distribution system. Unbalanced power system operation requires an unbalanced load flow analysis in order to assess true system feasibility. This paper presents an innovative unbalance load flow analysis method with the presence of unbalanced operation of SVCs (Static Var Compensators) and STATCOMs (STATic COMpensators). Unlike the existing methods, the proposed method applies reduced steps in the calculation, and the parameter limits are dynamically determined in an iterative process. Case studies demonstrate its improved convergence characteristics, reduced computing demand and the robustness of the solution.

Optimal coordination of unbalanced power distribution systems with integrated photovoltaic systems and semi‐fast electric vehicles charging stations

“…The load flow calculation involves constructing a Y matrix that reflects the network per-phase impedance, including Carson's line formulation. The detailed mathematical formulation of the three-phase load flow calculation used to calculate the power losses can be found in [26].…”

“…The improved load flow algorithm presents a superior performance in convergence and computing time compared with other Newton-Raphson methods. Full details of the improved three-phase load flow and its performance can be found in [26].…”

“…The load flow calculation involves constructing a Y matrix that reflects the network per‐phase impedance, including Carson's line formulation. The detailed mathematical formulation of the three‐phase load flow calculation used to calculate the power losses can be found in [26]. $$\begin{equation}{f^{PL}} = \mathop \sum \limits_{i = 1}^N \mathop \sum \limits_{p = a,b,c} \left(P_{G\_i}^p - P_{L\_i}^p\right).\end{equation}$$…”

“…Therefore, several modifications are required to the existing load flow algorithms and sometimes cause convergence problems and demand high computation time. To address this problem, the author has proposed an innovative model of three‐phase DSTATCOM in [26], which can be used in unbalanced load flow calculation. In this paper, the developed DSTATCOM model will be used where its connected bus is modelled as a voltage‐controlled bus in load flow calculation with an identified voltage magnitude and zero active power exchange when it operates within limits.…”

“…In the optimisation problem, the voltage magnitude is treated as a control variable, and then DSTATCOM model parameters for each phase can be calculated at the end of each iteration of the load flow calculation to check its limits. Full details of the developed DSTATCOM and its performance in terms of computation time and solution convergence can be found in [26]. OLTC …”