DSO–TSO Coordination of Day-Ahead Operation Planning with the Use of Distributed Energy Resources

Rafal Dzikowski

doi:10.3390/en13143559

Abstract

Growing penetration of uncoordinated Distributed Energy Resources (DERs) in distribution systems is contributing to the increase of the load variability to be covered at the transmission system level. Forced, fast and substantial changes of power plants’ output powers increase the risk of their failures, which threatens the reliable and safe delivery of electricity to end users in the power system. The paper handles this issue with the use of DERs and proposes a bilevel coordination concept of day-ahead operation planning with new kind of bids to be submitted by Distribution System Operators (DSOs) to the Transmission System Operator (TSO). This concept includes the extension of the Unit Commitment problem solved by TSO and a new optimization model to be solved by DSO for planning a smoothed power profile at the Transmission–Distribution (T–D) interface. Both optimization models are described in the paper. As simulations show, the modified 24-h power profiles at T–D interfaces result in a reduction of the demand for operation flexibility at the transmission system level and, importantly, result in a decrease of the number of conventional power plants that are required to operate during a day. Additionally, it has been proved that the modified profiles reduce the congestions in the transmission network. Hence, the concept presented in the paper can be identified as an important step towards the transformation of power systems to low-emission and reliable systems with high share of DERs.

Highlights

In the past, the main electricity sources in power systems were thermal power plants
A single modified 24-h profile at the T–D interface was obtained by solving the dedicated optimization model, which dispatches local Distributed Energy Resources (DERs) and makes effort to decrease the variability of the power profile at the T–D interface
The growing share of uncoordinated Distributed Energy Resources (DERs) increases the variability of the load to be covered by conventional power plants

Summary

Introduction

The main electricity sources in power systems were thermal power plants. Output powers of wind turbines and photovoltaics (PVs), which play a dominant role in this transformation [1], fluctuate in accordance with the variability of local weather-dependent conditions, and other DERs, like energy storage systems or biogas-fired turbines, operate in a way maximizing independently their own financial profits. Such operation of DERs without regard to the their impact on power system operation, called the ‘produce-and-forget’ approach [2], has consequences if their share becomes significant. The residual load, which is understood as total electric power consumption minus output powers of all DERs in the power system, is characterized by larger differences between maximum and minimum values during a day, more frequent and sharp changes in time and less repeatability of the profile shape day after day

Methods

Results

Conclusion