계통관성에 따른 과회복주파수의 발전기 출력 왜곡 분석 및 ESS 기반 관성보상 운전전략에 관한 연구 = A Study on Generator Output Distortion During Frequency Overshoot According to System Inertia and ESS-Based Inertia Compensation Operating Strategies

다국어 초록 (Multilingual Abstract)

With the expansion of renewable energy and the reduction of synchronous generators, the inertia of the power system has declined, resulting in larger frequency change rates and deeper Nadir values for the same magnitude of power imbalance. In low-inertia systems, frequency overshoot?where system frequency exceeds the nominal value during the post-fault recovery stage?appears more prominently. During this overshoot interval, frequency rises while generator active power output may temporarily decrease, potentially causing distortions in energy delivery and Governor-Free (GF) performance assessment. Nevertheless, existing standards and prior studies have focused primarily on Nadir and steady-state frequency, leaving the relationship between system inertia, frequency overshoot, and generator output distortion insufficiently examined.
This study aims to quantify the characteristics of frequency overshoot under different system inertia conditions and evaluate its associated impact on generator output distortion, particularly in the context of GF assessment in low-inertia grids. To this end, the start and end instants, duration, and maximum amplitude of the overshoot interval were defined within the post-fault frequency response, and an indicator linking these with the corresponding active-power variation of generators was established. A 200-MW single test system was modeled by varying only the inertia parameters, and the same analysis procedure was applied to a renewable-rich, reduced-order Jeju system to validate the results under conditions closer to actual system operation.
The analysis confirms that, under low-inertia conditions, increased overshoot amplitude and duration lead to an expansion of the generator output-reduction interval, and when this interval overlaps with the GF evaluation window, discrepancies arise between the generator’s actual recovery contribution and its assessed performance. Meanwhile, applying an energy-neutral ESS (Energy Storage System) operational rule?absorbing surplus energy during overshoot and discharging the same amount afterward?was found to mitigate overshoot magnitude and generator output distortion. The proposed indicators and scenarios supplement existing Nadir-based frequency stability evaluation and can serve as foundational references for revisiting GF assessment frameworks and ESS operational strategies in low-inertia, high-renewable power systems.

목차 (Table of Contents)

• 제1장 서 론 1
• 1.1 연구배경 1
• 1.2 과회복주파수 및 GF운전 이론적 고찰 6
• 1.3 연구 목적·범위 및 논문 구성 11
• 제2장 본론 13
• 2.1 과회복주파수의 정의 13
• 2.2 연구절차 16
• 2.2.1 시나리오 1 : 관성차이에 의한 과회복주파수 측정 및 비교 17
• 2.2.2 시나리오 2 : 과회복주파수의 발전기 출력 영향 측정 18
• 2.2.3 시나리오 3 : 과회복주파수 연계 ESS 투입 기법 연구 20
• 2.3 모의계통 연구 시나리오 22
• 2.3.1 모의계통 구성 및 사고 설정 22
• 2.3.2 모의계통에서의 시나리오 1 23
• 2.3.3 모의계통에서의 시나리오 2 25
• 2.3.4 모의계통에서의 시나리오 3 27
• 2.4 제주계통 연구 시나리오 31
• 2.4.1 제주계통 구성 및 사고 설정 31
• 2.4.2 제주계통에서의 시나리오 1 32
• 2.4.3 제주계통에서의 시나리오 2 34
• 2.4.4 제주계통에서의 시나리오 3 37
• 제3장 결 론 40
• 참고문헌 42
• ABSTRACT 45