Effect of Reactive Power Limit Modeling on Maximum System Loading and Active and Reactive Power Markets

Abstract

This paper presents a comparative investigation of various representations of reactive power limits in maximum loadability and active and reactive power market studies. Previously proposed optimal power flow (OPF) models for these types of analyses are first reviewed and briefly discussed. Different models for representing reactive power limits in these optimization problems are then presented, concentrating in particular on the proper modeling of the generators' capability curves as terminal voltages change, which has been identified as a shortcoming of previous studies. Comparative numerical analyses of the effect of various reactive power limit models in maximum loading and active and reactive power dispatch and pricing levels are presented and discussed, to thus quantify the effect these various limit representations have on the corresponding results. Two test systems, namely, the CIGRE-32 benchmark system and a 1211-bus dispatch model of a European network, are used for numerical studies. The presented results show that in most OPF applications, the improvement on the reactive power limits representation lead to subtle differences at the cost of increased computational complexity, which in some cases may be difficult to justify in practice.Index Terms-Electrical energy markets, generator capability curves, maximum loadability, optimal power flows, reactive power limits, reactive power markets, voltage stability.

On the inter-area optimal voltage and reactive power control

“…The coordination is attained via a coupling constraint, forcing the border variables to be equal [26]. By considering these coupling constraints into the objectives, the following optimization is reached subject to (21) and (22).…”

“…The maximum reactive power support of a generator is obtained considering the limitation of the field current (13) and the limitation of the armature current (14). Literatures show that the explicit representation of generators terminal voltages on generators capability limits plays a dominant role [22].…”

Maximum Voltage Stability Margin Problem With Complementarity Constraints for Multi-Area Power Systems

“…The modeling of the generators reactive power limits has received lots of attention [15]- [17], [20], [21]. For a given active power output, the maximum reactive power support of a generator ( ) is constrained by the limitation of the field current ( ), the limitation of the armature current ( ) and the under-excitation limit [22].…”

“…Nevertheless, the explicit representation of generator capability limits plays a dominant role in emergency states [16], [21]. These complementarity constraints (2a) and (2b) could be, respectively, taken into consideration by the following nonlinear constraints:…”

Study of the reactive power control for a real UHVAC power transmission project

“…Therefore, a reasonable reactive power control strategy that minimizes the RPI between the 1000 and 500 kV grids should be developed. In recent years, researchers have made wide and in-depth studies on the reactive power optimization technique [2][3][4][5][6][7]. However, the reactive power control strategy of UHVAC projects is rarely discussed.…”