Evaluation of Network Equivalents for Voltage Optimization in Multi-Area Power Systems

Abstract

Abstract-The paper addresses the problem of decentralized optimization for a power system partitioned into several areas controlled by different transmission system operators (TSOs). The optimization variables are the settings for taps, generators' voltages and compensators', and the objective function is either based on the minimization of reactive power support, the minimization of active power losses, or a combination of both criteria. We suppose that each TSO assumes an external network equivalent for its neighboring areas and optimizes without concern for the neighboring systems' objectives its own optimization function. We study, in the context where every TSO adopts the same type of objective function, the performance of an iterative scheme, where every TSO refreshes at each iteration the parameters of its external network equivalents depending on its past internal observations, solves its local optimization problem, and then, applies its "optimal actions" to the power system. In the context of voltage optimization, we find out that this decentralized control scheme can converge to nearly optimal global performance for relatively simple equivalents and simple procedures for fitting their parameters.Index Terms-Decentralized control, multi-TSO power system operation, network equivalent, reactive power scheduling, voltage management.

BFS algorithm for voltage-constrained meshed DC traction networks with nonsmooth voltage-dependent loads and generators

“…The selected threshold ( ) for the stop criteria expressed in the expression (17) is 10 −6 . The convergence of this method will be demonstrated by means of empirical methods [26]- [31]. The evolution of the error with respect to the time, the number of iterations and other parameters described in the following paragraphs have been analyzed for a large number of test batteries.…”

Coordination of voltage control in a power system operated by multiple transmission utilities

“…While different types of network equivalents are possible, reference [14] shows that modeling the external network with a constant active and reactive power injection at every point of interconnection yields close to optimal performance even if the TSOs' control actions are not coordinated by a centralized authority.…”

“…In particular, Reference [14] presents a decentralized scheme for reactive power scheduling, where the TSOs concurrently schedule long-term voltage settings within their own control area, while representing the neighboring areas with external network equivalents whose parameters are fitted based on local measurements only. Previous papers [14], [15] have shown that such a coordination scheme could lead to close to optimal settings in the context of small-scale power system models. Furthermore, this promising scheme could be easily implemented on a real power system as it involves few departures from the current practices.…”

“…This paper provides an evaluation of the centralized control scheme proposed in [8] and the decentralized control scheme proposed in [14] on a 4141 bus power system representing the western part of the UCTE system, which is operated by 7 different TSOs. Those strategies are also compared with the current practice in the UCTE system, modeled as a particular instance of the decentralized coordination scheme.…”

A fair method for centralized optimization of multi-TSO power systems

“…On one hand, ad-hoc decentralized control schemes have been proposed, as in [5], [6] for example. On the other hand, efforts have been made to create higher-level entities, which would be in charge of coordinating operation over very large geographical areas.…”