Dynamic Optimal Power Flow for Active Distribution Networks

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 intertemporal 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 Dynamic Optimal Power Flow 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 non-firm 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. Index Terms-Energy storage, Flexible demand, Active Network Management, OPF, dynamic optimal power flow I. NOMENCLATURE 1 General DOPF Vector of OPF control variables Vector of OPF fixed parameters Vector of intertemporal variables Vector of OPF derived variables Objective function OPF equality constraints OPF inequality constraints Intertemporal equality constraints Intertemporal inequality constraints This work is partly funded through the in Wind Energy Systems Centre for Doctoral Training at the University of Strathclyde. EPSRC EP/G037728/1.

Valuation of stored energy in dynamic optimal power flow of distribution systems with energy storage

“…A number of similar models have been reported in the literature in recent years; see e.g. [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]. A typical problem these models are set out to solve is determining the optimal scheduling of energy storage charging/discharging over a planning horizon, e.g.…”

“…In the model presented in the present paper, we consider an additional aspect that to the best of our knowledge is not explicitly considered in the literature, namely the value of stored energy at the end of the planning horizon. The conventional approach is to require periodic boundary conditions for the planning horizon so that the amount of stored energy after the last time step has to be equal to, or larger than, the initial amount of stored energy [7][8][9][10][11][12][13][14][15][16][17]. Reference [18] instead includes a penalty function in the objective function that is proportional to the deviation of the amount of stored energy from the maximal energy capacity, promoting a fully charged energy storage at the final time step.…”

Using Dynamic Optimal Power Flow to Inform the Design and Operation of Active Network Management Schemes

“…Dynamic Optimal Power Flow (DOPF) extends OPF to multiple time-steps which are linked by the creation of additional intertemporal variables and constraints. The formulation of a DOPF is similar to that of an OPF [7]. An objective function, f, is minimized:…”

Coordinated scheduling model of power system with active distribution networks based on multi-agent system

“…From then on, Active distribution network has received extensive attention. Many scholars began to study the generation schedule in ADNs to improve the acceptance level of DG resources, such as optimal power flow [5], reactive power optimization [6], day ahead and real-time scheduling [7], active and reactive power coordinated schedule [8,9]. On the other hand, coordinated dispatch between ADN and transmission network (TN) has become a new issue, which is also the topic of this article.…”