Transmission and distribution coordination in power systems with high shares of distributed energy resources providing balancing and congestion management services

Abstract

This paper presents a literature review on the coordination between transmission and distribution grid operators in power systems, with particular emphasis on the provision of balancing and congestion management services. Firstly, a brief historical background is presented in order to highlight the ongoing changes current power systems are experiencing and that call for greater coordination between transmission system operators (TSO) and distribution system operators (DSO).These include the growth in distributed energy resources (DER), new roles to be adopted by both system operators (SO), and the integration of new agents such as independent aggregators. Next, the paper places its focus on a particular topic which, based on the review presented, is presumably considered as the most relevant issue requiring tighter cooperation mechanisms, that is, the procurement of balancing services from DER by TSOs whilst DSOs procures the same DER flexibility to manage local congestions. Four key elements are identified for this coordination to take place, namely (a) DER flexibility integration, (b) coordination schemes, (c) transmission-distribution optimization, and (d) data exchange. For each one of them, the paper presents a literature review and identifies the main existing technical, economic, and regulatory barriers. These barriers include, among others, the limitation for small DER flexibility to participate in grid service markets, the challenges for independent aggregators, the technical barriers for optimizing a transmission-distribution grid, and the lack of maturity in coordination schemes and TSO-DSO data exchange models.

A Review on TSO-DSO Coordination Models and Solution Techniques

“…With this model, the TSO is responsible for the DER and TER dispatch [16][17][18][19] (i.e., a fully centralised dispatch) while accounting for both transmission and distribution networks constraints [20][21][22]. Depending on the energy market design, an independent market operator could also be the entity responsible for this task (e.g., Australian Energy Market Operator, AEMO, in Australia).…”

“…The distribution-level market is cleared before DER bids are sent to the TSO market [5,[16][17][18][19][20]43]. For this scheme, only steps 2 and 4 are modified.…”

Advanced Flexibility Market for System Services Based on TSO–DSO Coordination and Usage of Distributed Resources

“…There are ideas to apply the active generation from TS in the congestion management by the concept of traffic lights [3,10]. Reference [11] proposed to assign each state from the traffic light concept to the proper state of congestion.…”

“…Moreover, there is a need to use flexible resources located in DS, when there is a need from a technical or economical point of view. What is more, now the distribution system is working in a "fit-and-forget" approach [3], which is related to the state in which infrastructure is oversized, to be able to cover peak values of the flow. This approach probably will exist and gain importance in the future, due to an increase in installed power of distributed generation and changes within the power system.…”

Little time left to reverse emissions—Growing hope despite disappointing CO2 trend

“…We see a major growth of papers on integration of renewables into the existing energy systems and on different systemic issues, which are becoming vital when the share of variable renewables grows. The theme of integration touches not only technical systems and their new requirements (Lind, Cossent, Chaves-Avila, & Gómez San Román, 2019;Sajadi, Strezoski, Strezoski, Prica, & Loparo, 2019), but also the planning of future energy systems (Doubleday, Hafiz, Parker, et al, 2019;Helistö, Kiviluoma, Holttinen, Lara, & Hodge, 2019), necessary market reforms and regulation (Algarvio, Lopes, Couto, Santana, & Estanqueiro, 2019;Skytte & Bobo, 2019), and new technologies such as power-to-gas to master large volumes of wind and solar power (Ajanovic & Haas, 2019). Invited papers have dealt on nationwide analytical scale with macroscale limitations and opportunities (Guminski, Böing, Murmann, & von Roon, 2019;Li, Zhang, Chen, & Lu, 2019).…”