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Analyzing the Impact of Demand Response on Short-Circuit Current via a Unit Commitment Model

Peng Wang, Zhengmao Li, Luis Badesa

TL;DR

This paper tackles how Demand Response (DR) affects Short-Circuit Current (SCC) provisioning in grids transitioning toward Inverter-Based Resources (IBR). It introduces a Unit Commitment (UC) model that jointly optimizes DR and SCC constraints, using a training-based, linear SCC approximation with McCormick envelopes and incorporating Interruptible Load (IL) and Shiftable Load (SL). Case studies on a modified IEEE 30-bus system show that DR can substantially reduce social costs but may degrade SCC if SGs withdraw; imposing SCC constraints while leveraging DR maintains security with only about a 0.3% cost increase, demonstrating a cost-effective path to stable operation in low-carbon grids. The work highlights the importance of considering protection reliability (SCC) when deploying DR in systems with high penetrations of IBR and offers a tractable MILP framework for integrated planning and operation.

Abstract

In low-carbon grids, system flexibility can be enhanced through mechanisms such as Demand Response (DR), enabling the efficient utilization of renewable energy. However, as Synchronous Generators (SGs) are being replaced with renewable energy characterized by Inverter-Based Resources (IBR), system stability is severely affected. Due to the limited overload capability of IBR, their Short-Circuit Current (SCC) contribution is much smaller than that of SGs, which may result in protection devices failing to trip during faults. Consequently, the remaining SGs play a key role in offering sufficient SCC volumes. Given that the commitment of SGs is closely related to system load, DR can thus indirectly affect their SCC provision, a relationship that has not been investigated. Therefore, this paper incorporates both DR and SCC constraints into a unit commitment model and conducts studies on an IEEE 30-bus system. The results show that although DR can reduce social costs by lowering power demand, it may also lead to inadequate SCC levels. Nevertheless, the cost increases by only 0.3% when DR is combined with SCC constraints, indicating that DR can actually help achieve a stable system in a cost-effective manner.

Analyzing the Impact of Demand Response on Short-Circuit Current via a Unit Commitment Model

TL;DR

This paper tackles how Demand Response (DR) affects Short-Circuit Current (SCC) provisioning in grids transitioning toward Inverter-Based Resources (IBR). It introduces a Unit Commitment (UC) model that jointly optimizes DR and SCC constraints, using a training-based, linear SCC approximation with McCormick envelopes and incorporating Interruptible Load (IL) and Shiftable Load (SL). Case studies on a modified IEEE 30-bus system show that DR can substantially reduce social costs but may degrade SCC if SGs withdraw; imposing SCC constraints while leveraging DR maintains security with only about a 0.3% cost increase, demonstrating a cost-effective path to stable operation in low-carbon grids. The work highlights the importance of considering protection reliability (SCC) when deploying DR in systems with high penetrations of IBR and offers a tractable MILP framework for integrated planning and operation.

Abstract

In low-carbon grids, system flexibility can be enhanced through mechanisms such as Demand Response (DR), enabling the efficient utilization of renewable energy. However, as Synchronous Generators (SGs) are being replaced with renewable energy characterized by Inverter-Based Resources (IBR), system stability is severely affected. Due to the limited overload capability of IBR, their Short-Circuit Current (SCC) contribution is much smaller than that of SGs, which may result in protection devices failing to trip during faults. Consequently, the remaining SGs play a key role in offering sufficient SCC volumes. Given that the commitment of SGs is closely related to system load, DR can thus indirectly affect their SCC provision, a relationship that has not been investigated. Therefore, this paper incorporates both DR and SCC constraints into a unit commitment model and conducts studies on an IEEE 30-bus system. The results show that although DR can reduce social costs by lowering power demand, it may also lead to inadequate SCC levels. Nevertheless, the cost increases by only 0.3% when DR is combined with SCC constraints, indicating that DR can actually help achieve a stable system in a cost-effective manner.

Paper Structure

This paper contains 11 sections, 5 equations, 7 figures, 4 tables.

Table of Contents

  1. Introduction
  2. Methodologies and Models
  3. Models of Short-Circuit Current Constraints
  4. Models of Demand Response
  5. Interruptible Load
  6. Shiftable Load
  7. SCC Constrained UC Model with DR
  8. Case Studies
  9. System Operation without SCC Constraints
  10. SCC Constrained System Operation
  11. Conclusion

Figures (7)

  • Figure 1: Modified IEEE 30-bus system.
  • Figure 2: Actual and linearized SCC values for IBR in bus 1.
  • Figure 3: Energy price and system demand in the case of no SCC constraints. SL-in(resp. out) denotes the shifted in(resp. out) flexible load. IL-I, IL-II and IL-III represent three types of IL, respectively.
  • Figure 4: Generators whose commitment state is affected by DR.
  • Figure 5: Unconstrained minimum SCC level at each bus.
  • ...and 2 more figures