Technical and economical assessment of reactive power provision from distributed generators: Case study area of East Denmark

Abstract

The transformation of the electrical energy system with traditional central power generation into a system of high penetration of distributed generation, requires a change in the current system operation practices. It is expected that a significant number of central power plants, which traditionally provided most ancillary services, will be taken out of operation during the next decades. From a technical and economic perspective, this paper evaluates the potential of reactive power provision from the distribution grid to the transmission grid. This approach is compared to reactive power provision from conventional dynamic reactive power compensators regarding technical and economic aspects. It will be shown that distributed generators can provide reactive power while being cost-competitive to conventional techniques

Analysis of a reactive power exchange between distribution and transmission grids

“…For example, a larger penetration of DGs may help to meet both reactive set points in Scenario II. A further important factor is the load state of the distribution grid [7]. On a low-load day (e.g.…”

“…A future Danish grid scenario is chosen, composed for a series of renewable integration studies in the TWENTIES project [7].…”

“…The optimizer respects the following limits for this particular distribution grid [7]. All bus voltages must stay between 1.0 and 1.08 p.u.…”

“…Consequently, distribution grids are viewed as "ancillary service providers" from the TSO perspective. Unlike normal power plants, however, the potential for ancillary service depends on many factors -for example, the loading state and operating constraints [7].…”

A Framework to Utilize DERs’ VAR Resources to Support the Grid in an Integrated T-D System

“…The var related ancillary services have been mainly achieved by large synchronous generators and other strategically deployed var devices such as static synchronous compensator (STATCOM) and static var compensator (SVC). However, a growing footprint of distributed energy resources (DERs) is replacing fossil fuel based generation that may result in shortage of regional var availability [3], [4]. It has initiated a discussion on utilizing DERs as alternative sources in the future grid, along with bulk generation plants, to provide essential ancillary services to the grid such as ramping requirements, ensuring adequate inertia, and maintaining var reserves [5], [6].…”