Novel Techniques for Continuation Method to Calculate the Limit-induced Bifurcation of the Power Flow Equation

Abstract

This article proposes an improved continuation method to calculate the limit-induced bifurcation associated with the power flow equation due to the encounter with reactive power limits by generators. One of the distinguishing features is that the maximum loadability characteristics of limit-induced bifurcation are used for identification so that the computation efforts can be minimized. Another distinctive characteristic of the method is that, to ensure accuracy, the tangent vector of the continuation power flow equation at the reactive power limit encountering point is used to differentiate between limit-induced bifurcation and saddle-node bifurcation, as the latter also represents maximum loadability. The proposed method also adopts the conventional schemes of secant prediction, arc-length correction, and a new stepsize control, i.e., the convergence-dependent step-size control. Numerical results of the IEEE 118-bus system are used to illustrate the improvements of the proposed continuation method in comparison with the existing one.

Efficient method to identify saddle‐node and limit‐induced bifurcation points of power system

“…On the other hand, identifying LIBP of power systems has been addressed in a number of references, which either are based on complex predictor/corrector-based approaches [20][21][22], or do not address the SNBP identification [10,20,22]. In fact, to the best of the authors' knowledge, there are very few references, such as [1], which address both SNBP and LIBP identification of power systems using a single approach.…”

An approach to handle sudden load changes on static voltage stability analysis

“…As the load grows, generators reach their operational limits that, in turn, prevent them to contribute further with the EPS. During static voltage stability analysis, interest lies in constraints that limit the reactive power supplied by generating units, since they are capable to reduce significantly the MLP and even drive instability (YORINO; LI; SASAKI, 2005; CAO; CHEN, 2010;CHIANG et al, 1995;AJJARAPU, 2007;CHAKRABARTI, 1996).…”

“…The CPFLOW is regarded as an efficient and precise method to estimate the MLP and obtain PV curves. It became a standard approach to perform Voltage Stability Assessment (VSA) under a static framework for a known load growth direction and it is also utilized as a comparison benchmark for other techniques being developed (CAO; CHEN, 2010;CHIANG, 2008b).…”

“…The equivalent in two dimensions of this geometric interpretation is indicated in Figure 2.5(b). Just like the local parametrization, the arc-length one avoids the poor conditioning of the Jacabian matrix near the maximum loadability point, solving the divergence problems of the power flow formulation around this point (CHIANG et al, 1995;CAO;CHEN, 2010).…”

“…This corresponds to the Maximum Loadability Point (MLP) of the system, which is the highest load level where the power flow equations can be solved. Beyond this point there is no available stable equilibrium for the power system to operate (CANIZARES; ALVARADO, 1993;CHIANG et al, 1995;CAO;CHEN, 2010). Static techniques do not depict the behavior of the EPS as accurately as the dynamic ones, however they are computationally faster, which promotes their utilization in real time applications and situations that require the analysis several EPS configurations (GAO; KUNDUR; MORISON, 1996;BALU et al, 1992;ZHAO et al, 2015).…”