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백승묵,엄호용 대한전기학회 2022 전기학회논문지 Vol.71 No.11
This paper proposes an optimal electric load forecasting technique by applying several activation functions and optimization methods in the internal structure of the Long Short-Term Memory (LSTM) algorithm to forecast mid-term electric load in Korea. As the activation function, the rectified linear unit (ReLU) and hyperbolic tangent (Tanh) are used. Optimization methods such as stochastic gradient descent (SGD) and adaptive moment optimization (Adam) are compared in the paper. In the input data, daily peak load over past seven days, maximum and minimum temperatures are used. In order to increase the efficiency of learning, special weeks and special day load data are replaced. The proposed method shows stable and great performance with small average errors, compared to the RANN based forecasting method which is a previous study. Especially, the estimated error is improved in the summer and winter where the temperature changes significantly.
주파수 변화율 측정 기반 에너지저장장치 효과적인 제어 전략
백승묵,김유나,조한솔 대한전기학회 2022 전기학회논문지 Vol.71 No.10
The paper describes an effective control strategy for energy storage system (ESS) according to the severity of occurring in power system. ESS is generally used to mitigate the frequency oscillation against the power system disturbances. However, ESS can frequently operate even in situation where it is not necessary to operate due to small load change or small fluctuations in renewable energy. It can cause the frequency variations of the state of charge (SOC) of ESS and shorten the lifespan of the ESS. Therefore, the paper proposes effective control method to reduce the unnecessary operation of ESS by categorizing three control modes based on measured rate of change of frequency (ROCOF). The performance of the proposed method is verified through time domain simulation by applying it to the microgrid system
커널 밀도 추정 기법을 이용한 풍력발전량에 대한 확률론적 모델
백승묵,최주승 대한전기학회 2023 전기학회논문지 Vol.72 No.1
As the proportion of renewable energy sources that are intermittent and variability increases, system uncertainty is increasing, and a probabilistic analysis that can reflect these characteristics is required. In this paper, we propose a method for generating a probablistic wind power generation model using kernel density estimation. The boundary bias problem caused by using kernel density estimation for wind power generation data is eliminated through the boundary correction method, and a bandwidth suitable for the data can be selected through the bandwidth selector. Scenarios were created from probabilistic models made in various ways, and the accuracy of the models was validated by comparing them with real data. As a result, the accuracy was improved when the scenario was created by generating the model directly from the wind power generation data by estimating the kernel density estimation.
전력시스템 과도 안정도 향상을 위한 SSSC의 제어 모드 변환
백승묵(Seung-Mook Baek),박정욱(Jung-Wook Park) 대한전기학회 2009 대한전기학회 학술대회 논문집 Vol.2009 No.11
직렬형 FACTS 기기 (Static Synchronous Series Compensator, SSSC)는 유연송전시스템 (Flexible AC Transmission System, FACTS)의 일종으로서 지상전압을 송전선에 투입하여 전송 효율을 높이고 전력시스템의 안정도를 향상시키는데 사용되는 제어기이다. 즉, 송전선로에 용량성의 전압을 투입하여 선로의 유도성 임피던스를 줄여주어 전송효율을 증가시키게 된다. 하지만, 용량형 전압의 투입은 전력시스템에 외란이 발생하였을 때, 큰 사고전류를 유발할 수 있다는 단점을 가지고 있다. 따라서 본 논문에서는 전력시스템의 과도 안정도를 향상시키기 위해 전력시스템에 외란이 감지되었을 때, SSSC가 유도성 전압을 투입하도록 제어 기법을 변환하는 방법을 소개하고자 한다. 또한, RTDS (Real-Time Digital Simulator) 하드웨어를 이용하여 SSSC가 포함된 전력시스템을 모델링함으로서 실제와 비슷한 환경 하에서 두 가지 모드변환에 따르는 과도 안정도 향상을 평가하였다.
궤도민감도 분석에 기반하여 복입력 전력시스템 안정화 장치(Dual-Input PSS)의 비선형 파라미터 최적화 기법
白承默(Seung-Mook Baek),朴正旭(Jung-Wook Park) 대한전기학회 2008 전기학회논문지 Vol.57 No.6
This paper focuses on optimal tuning of nonlinear parameters of a dual-input power system stabilizer (dual-input PSS), which can improve the system damping performance immediately following a large disturbance. Until recently, various PSS models have developed to bring stability and reliability to power systems, and some of these models are used in industry applications. However, due to non-smooth nonlinearities from the interaction between linear parameters (gains and time constants of linear controllers) and nonlinear parameters (saturation output limits), the output limit parameters cannot be determined by the conventional tuning methods based on linear analysis. Only ad hoc tuning procedures ('trial and error' approach) have been used. Therefore, the steepest descent method is applied to implement the optimal tuning of the nonlinear parameters of the dual-input PSS. The gradient required in this optimization technique can be computed from trajectory sensitivities in hybrid system modeling with the differential-algebraic-impulsive-switched (DAIS) structure. The optimal output limits of the dual-input PSS are evaluated by time-domain simulation in both a single machine infinite bus (SMIB) system and a multi-machine power system in comparison with those of a single-input PSS.
하이브리드시스템 모델링 기반 발전기 전력시스템 안정화장치 정수선정 기법
백승묵(Seung-Mook Baek) 대한전기학회 2014 전기학회논문지 Vol.63 No.7
The paper describes the parameter tuning of power system stabilizer (PSS) for a power plant based on hybrid system modeling. The existing tuning method based on bode plot and root locus is well applied to keep power system stable. However, due to linearization of power system and an assumption that the parameter ratio of the lead-lag compensator in PSS is fixed, the results cannot guarantee the optimal performances to damp out low-frequency oscillation. Therefore, in this paper, hybrid system modeling, which has a DAIS (differential-algebraic-impusive-switched) structure, is applied to conduct nonlinear modeling for power system and find optimal parameter set of the PSS. The performances of the proposed method are carried out by time domain simulation with a single machine connected to infinite bus (SMIB) system.