Active Network Management

Abstract: Increasing connection of variable distributed generation, like wind power, to distribution networks requires new control strategies to provide greater flexibility and use of existing network assets. Active network management (ANM) will play a major role in this but there is a continuing need to demonstrate the benefit in facilitating connection of new generation without the need for traditional reinforcements. This paper proposes a multi-period AC optimal power flow (OPF)-based technique for evaluating the maximum capacity of new variable distributed generation able to be connected to a distribution network when ANM control strategies are in place. The ANM schemes embedded into the OPF include coordinated voltage control, adaptive power factor and energy curtailment. A generic U.K. medium voltage distribution network is analyzed using coincident demand and wind availability data derived from hourly time-series. Results clearly show that very high penetration levels of new variable generation capacity can be achieved by considering ANM strategies compared to the widely used passive operation (i.e., "fit and forget"). The effects on network losses are also discussed.

Abstract: Active Network Management is a philosophy for the operation of distribution networks with high penetrations of renewable distributed generation. Technologies such as energy storage and flexible demand are now beginning to be included in Active Network Management (ANM) schemes. Optimizing the operation of these schemes requires consideration of inter-temporal linkages as well as network power flow effects. Network effects are included in optimal power flow (OPF) solutions but this only optimizes for a single point in time. Dynamic optimal power flow (DOPF) is an extension of OPF to cover multiple time periods. This paper reviews the generic formulation of DOPF before developing a framework for modeling energy technologies with inter-temporal characteristics in an ANM context. The framework includes the optimization of nonfirm connected generation, principles of access for nonfirm generators, energy storage, and flexible demand. Two objectives based on maximizing export and revenue are developed and a case study is used to illustrate the technique. Results show that DOPF is able to successfully schedule these energy technologies. DOPF schedules energy storage and flexible demand to reduce generator curtailment significantly in the case study. Finally, the role of DOPF in analyzing ANM schemes is discussed with reference to extending the optimization framework to include other technologies and objectives.

Abstract: As the amount of distributed generation (DG) is growing worldwide, the need to increase the hosting capacity of distribution systems without reinforcements is becoming nowadays a major concern. This paper explores how the DG hosting capacity of active distribution systems can be increased by means of network reconfiguration, both static, i.e., grid reconfiguration at planning stage, and dynamic, i.e., grid reconfiguration using remotely controlled switches as an active network management (ANM) scheme. The problem is formulated as a mixed-integer, nonlinear, multi-period optimal power flow (MP-OPF) which aims to maximize the DG hosting capacity under thermal and voltage constraints. This work further proposes an algorithm to break-down the large problem size when many periods have to be considered. The effectiveness of the approach and the significant benefits obtained by static and dynamic reconfiguration options in terms of DG hosting capacity are demonstrated using a modified benchmark distribution system.

Abstract: Governance networks are characterized by complex interaction and decision making, and much uncertainty. Surprisingly, there is very little research on the impact of trust in achieving results in governance networks. This article asks two questions: (a) Does trust influence the outcomes of environmental projects? and (b) Does active network management improve the level of trust in networks? The study is based on a Web-based survey of respondents involved in environmental projects. The results indicate that trust does matter for perceived outcomes and that network management strategies enhance the level of trust.