Robust prequalification process of a distribution system operator considering N‐1 contingency

Abstract

A distributed energy resource aggregator (DERA) participates in the wholesale energy market (WEM) on behalf of aggregated distributed renewable energy sources (DRESs). The DERA manages DRESs according to the dispatch signal from the system operator (SO). However, a conventional independent SO that operates the WEM and transmission system does not monitor the distribution system. Therefore, overvoltage or overflow problems can occur during the generation of DRESs in a distribution system in which bids are accepted in the WEM. To address these problems, previous studies proposed the prequalification process. In the process, a distribution SO (DSO), which is responsible for the reliability of the distribution system, reviews DERA's bids before it is submitted to the WEM. However, these studies do not consider the outages of the system components. Therefore, we propose an N‐1 contingency prequalification process (N‐1 PP). The DSO manages the DERA's bid considering both the uncertainties and system states after the reconfiguration in contingency situations. In the proposed scheme, the DERA's bid is reviewed for severe faults and post‐reconfiguration systems. The results indicate that the N‐1 PP is more stable and durable than the prequalification process of previous studies.

Field Experiment for a Prequalification Scheme for a Distribution System Operator on Distributed Energy Resource Aggregations

“…This paper aims to summarize and share the demonstration result of KEPCO's project consortium to create a TSO-DSO-DERA interaction system. It describes the process of improving the theoretical algorithm proposed in papers [7,8] to apply to the actual demonstration site and verification through actual field experiments.…”

“…On the other hand, refs. [7,8] pro-posed a system for DSOs to verify the bids of DERAs based on robust optimization to handle uncertainties in generation and load. These two papers are unique in that they pro-pose an interaction scheme with a design based on the legal authority of each entity in the real world, and they present the idea of converting robust optimization based on chance-constrained optimization into a cooperative solution based on linearized information exchange between entities.…”

“…In particular, this project focused on the interaction between DSO and DERAs who want to participate in the TSO market, and demonstrated a prequalification scheme for two distribution lines of KEPCO. The references [7,8] are the deliverables from this demonstration project. In addition to the day-ahead prequalification, this project also included a demonstration of the direct control scheme of the DSO in a real-time situation, which is beyond the scope of this paper and is not described.…”

Optimal VPP Operation Considering Network Constraint Uncertainty of DSO

“…The DERA submits a bidding plan to the DSO before participating in the market, and then the DSO provides a modification guideline with the suggestion of how to adjust and approve the plan. Jeong et al [21] proposed a DSO pre-qualification process considering N-1 contingency situations. The DSO provides modification guidelines considering uncertain situations, such as outages of the distribution system, to manage the system more stably than in the previous study [20].…”

Field Experiment for Prequalification Scheme of Distribution System Operator on Distributed Energy Resource Aggregations

“…Another study proposed a scheme in which the DSO and TSO each operate an own balancing market, and DER bids go directly to the TSO market bids if they do not cause problems on the distribution grid, and if they do, they are cleared within the DSO's balancing market first and the adjusted bids go to the TSO market [8]. On the other hand, [9] and [10] proposed a system for DSOs to verify bids of DERAs based on robust optimization for handling uncertainty in generation and load. These two papers are unique in that they propose an interaction scheme designed based on the legal authority of each entity in the real world, and they present the idea of converting a robust optimization based on chanceconstrained optimization into a cooperative solution based on linearized information exchange between entities.…”