Net Load Carrying Capability of Generating Units in Power Systems

Chang-Gi Min,Mun-Kyeom Kim

doi:10.3390/en10081221

Abstract

This paper proposes an index called net load carrying capability (NLCC) to evaluate the contribution of a generating unit to the flexibility of a power system. NLCC is defined as the amount by which the load can be increased when a generating unit is added to the system, while still maintaining the flexibility of the system. This index is based on the flexibility index termed ramping capability shortage expectation (RSE), which has been used to quantify the risk associated with system flexibility. This paper argues that NLCC is more effective than effective load carrying capability (ELCC) in quantifying the contribution of the generating unit to flexibility. This is explained using an illustrative example. A case study has been performed with a modified IEEE-RTS-96 to confirm the applicability of the NLCC index. The simulation results demonstrate the effect of operating conditions such as operating point and ramp rate on NLCC, and show which kind of unit is more helpful in terms of flexibility.

Highlights

The high penetration of renewable energy resources (RES) has made it more difficult to secure flexibility in power systems, which is defined as the ability to respond to changes in net load, i.e., load minus output of non-dispatchable RES [1,2,3,4]
This paper proposed aa concept contribution of of a generating unitunit to the the flexibility a power system, which is defined as ability the ability to respond to changes in load
Flexibility of aofpower system, which is defined as the to respond to changes in net is defined as the amount whichthe theload loadcan canbe beincreased increased while while maintaining the same is defined as the amount byby which same flexibility flexibility

Summary

Introduction

The high penetration of renewable energy resources (RES) has made it more difficult to secure flexibility in power systems, which is defined as the ability to respond to changes in net load, i.e., load minus output of non-dispatchable RES [1,2,3,4]. System planners and operators have tried to secure an adequate level of reserve capacity in view of reliability This approach does not guarantee flexibility, because the problem can be caused by a shortage in ramping capability (i.e., the ability to change the output of a generating unit in a given period), despite there being sufficient reserve capacity [5,6]. The greater the ramping capability, the stronger the ability of the system to react to unexpected changes in net load; that is, larger and faster units are helpful for coping with the flexibility issue This issue is directly related to both generation scheduling and generation expansion planning (GEP) [11,12,13,14]. To the best of our knowledge, [19]

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