This paper presents a novel distributed voltage control strategy to maintain the voltage of active distribution networks containing multiple microgrids. Local voltage regulation characteristics, such as power reserve, adjustment cost, and regulating speed, are identified first. According to a neighbors’ voltage regulation characteristics, the microgrid coordinates neighborhood resources and asks them for coordination as soon as voltage problems occur. Microgrids schedule local resources based on a cooperative distributed model predictive control algorithm scheme with neighbor-to-neighbor communication. Tests are performed in an active distribution network with three microgrids. The numerical studies have shown that the proposed strategy mitigates the voltage fluctuation rapidly and efficiently with minimum operating cost.

A Distributed Voltage Control Strategy for Multi-Microgrid Active Distribution Networks Considering Economy and Response Speed

Reactive power cost allocation by power tracing based method

Modern power system is moving towards a smart and competitive grid, with competing generating companies, power retailers, and strategically behaving consumers playing a crucial role in the daily operation of the system Independent System Operator (ISO) monitors these daily operations and procure required services through market operations Active and reactive power pricing in real-time at the wholesale and retail level is considered an efficient energy management method However, procurement of reactive power through a market mechanism in real-time is not being implemented, despite its crucial role in maintaining system parameters within the permissible limits This paper attempts to detail the challenges faced in implementing such reactive power markets and presents a review of existing reactive power market mechanisms to address these challenges A framework suitable for reactive power ancillary service in a smart grid is also detailed in this paper

A comprehensive survey on reactive power ancillary service markets

In deregulated power systems, reactive power ancillary service through electricity market is becoming relevant where private generation companies participate in maintaining system wide bus voltage within the permissible limits. Marginal cost price (MCP) based real time reactive power ancillary service market faces several challenges due to the localized nature of reactive power. In this paper, a market mechanism for real time reactive power ancillary service market based on Stackelberg game model is proposed considering voltage-apparent power coupled subsystems. In the proposed Stackelberg game model, Independent System Operator (ISO) is considered as the leader, and GENCOs as followers. In the formulation, each GENCO is associated with a relevance factor in the partitioned subsystem so as to consider the real time voltage support requirement in the system. The market is then formulated as Mathematical Program with Equilibrium Constraints problem (MPEC). Existence of equilibrium, incentive compatibility, and individual rationality of the proposed market mechanism is then analysed in this work. The numerical examples are illustrated in PJM 5-bus system, and tested on IEEE 30- bus system, and Nordic 32 Bus-system. The mechanism induces truth-telling behavior of GENCOs, yields a non-negative profit, and the system wide bus voltage is improved.

Game Theoretical Approach to Novel Reactive Power Ancillary Service Market Mechanism

The provision of reactive power/energy for the purposes of voltage control of the transmission system is, pursuant to the Swiss Electricity Supply Act of 2007, part of the ancillary services market. In line with it, Swissgrid, the Swiss TSO, developed a concept for the coordinated voltage control of the 220/380-kV transmission system that enables, along with transmission connected power plants, the active participation of underlying distribution grids. The current paper outlines the voluntary active participation of transmission connected distribution transformers to the coordinated voltage control. It describes the concept's features and illustrates the behavior of active distribution transformers in terms of reactive power exchange, voltage quality at the connection node, as well as the associated financial incentives.

Contribution of active distribution grids to the coordinated voltage control of the swiss transmission system

This paper presents the characteristics of reactive power and voltage support and proposes two generic methods for pricing reactive power. The first is a capacity based method and the second is based on actual reactive power production. A combination of both is also presented in the paper as a possible alternative. The framework for reactive power management and pricing along with the specific market rules for the California market is further presented in detail.

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A.D. Papalexopoulos

Papers

Reactive power management and pricing in the California market