• 조명전기설비학회논문지
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• 제27권5호
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• pp.33-38
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• 2013

This paper presents a simpler calculation of the generator load sharing according to the change of system frequency and the droop setting of turbine-generator governor. The author firstly draws a graph based on the generator operation at rated MW output and normal frequency, and secondly, builds a proportional expression using the graph in order to obtain the solution in a simpler way rather than using conventional mathematical calculation, to provide the readers with an easier understanding of the droop setting of turbine-generator governor.

• Advances in Energy Research
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• 제3권2호
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• pp.81-95
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• 2015

Microgrid, which can be considered as an integration of various dispersed resources (DRs), is characterized by number of DRs interfaced through the power electronics converters. The microgrid comprising these DRs is often operated in an islanded mode. To minimize the cost, reduce complexity and increase reliability, it is preferred to avoid any communication channel between them. Consequently, the droop control method is traditionally adopted to distribute active and reactive power among the DRs operating in parallel. However, the accuracy of distribution of active and reactive power among the DRs controlled by the conventional droop control approach is highly dependent on the value of line impedance, R/X i.e., resistance to reactance ratio of the line, voltage setting of inverters etc. The limitations of the conventional droop control approach are demonstrated and a modified droop control approach to reduce the effect of impedance mis-match and improve the time response is proposed. The error in reactive power sharing is minimized by inserting virtual impedance in line with the inverters to remove the mis-match in impedance. The improved time response is achieved by modifying the real-power frequency droop using arctan function. Simulations results are presented to validate the effectiveness of the control approach.

• Journal of Electrical Engineering and Technology
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• 제6권1호
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• pp.42-47
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• 2011

Automatic generation control (AGC) is an important function for load frequency control, which is being implemented in Energy Management System (EMS). A key feature of AGC is to back up governors to enhance the performance of frequency control. The governor regulates system frequency in several to ten seconds, while the droop control concept results in steady-state control error. AGC is a supplementary tool for compensation of the steady-state error caused by the droop setting of the governors. As the AGC target is delivered to each generator as an open loop control target, the generator output is not guaranteed to follow the AGC target. In this paper, we introduce generating unit controller (GUC) control block, which has the purpose of enabling the generator output to track the AGC target while maintaining the governor performance. We also address the tuning methods of GUC for better performance of AGC in the Korea Energy Management System (K-EMS).

• 전기전자학회논문지
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• 제23권3호
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• pp.785-792
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• 2019

다중 컨버터 모듈을 병렬 운전 시, 시스템의 신뢰성 향상을 위해 모듈 간 균등한 전력 분배가 이루어져야 한다. 본 논문에서는 기존의 드룹 제어 방법을 개선하여 전류 분배 특성이 향상된 개선된 드룹 제어 방법을 제시한다. 제안하는 방법에서는 각 모듈의 전류가 설정값보다 커질 경우, 출력 전압 설정값을 상향 조정하여 모듈 간 전류 분배 특성이 개선되도록 한다. 한편, 출력 전압을 공차 범위 안에서 관리하고자 할 때, 출력 전압 설정값이 항상 상향 조정된다면 이용 가능한 제어 IC 기준값($v_{ref}$)의 범위가 줄어들게 된다. 따라서 상향 조정으로 인해 모듈 간 출력 전압 설정값이 역전될 경우 하향 조정을 통해 이를 해결하고자 하였다. 제안하는 방법은 2개의 부스트 컨버터 모듈로 구성된 17.5V/500mA급 프로토타입을 통해 실험으로 검증하였다.