• Title/Summary/Keyword: Reactive System

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Methodology for Determining of Generator Operation Point for Ensuring Voltage Stability Against Generator Faults in Jeju-Haenam HVDC System

  • Kang, Sang-Gyun;Seo, Sang-Soo;Lee, Byong-Jun;Joo, Joon-Young
    • Journal of Electrical Engineering and Technology
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    • v.5 no.1
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    • pp.54-60
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    • 2010
  • This paper presents a new algorithm for determining generator operation point for maintaining stability considering generator faults in Jeju-Haenam HVDC system. As the HVDC system consumes reactive power for the transmission of active power substantially, compensation of reactive power is essential. And the HVDC system is operated on frequency control mode. That is to say, the HVDC system almost manages system frequency. Therefore, we recognized that the Jeju system could be unstable if the reactive power consumed by the HVDC is insufficient when out-of-step occurs with large generators. When the solution of power flow analysis does not converge due to the unstable system phenomenon, we have difficulty in establishing countermeasures as the post-fault information is not available. In this paper, for the purpose of overcoming this difficulty in establishing countermeasures, we introduce the CPF(Continuation Power Flow) algorithm. This paper suggests an algorithm for calculating the output limitation of the generator to maintain the stability in case of generator fault in the Jeju system.

The Permeability Characteristics of the Reactive Soil - Bentonite Landfill Liner (혼합반응 차수재의 투수특성 연구)

  • 이강원;황의석;안기봉;정하익;김학문
    • Proceedings of the Korean Geotechical Society Conference
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    • 2002.10a
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    • pp.545-552
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    • 2002
  • The purpose of this paper is to investigate permeability characteristic of soil-bentonite landfill liner and development of desirable liner system. In this study, permeability tests for soil-bentonite, reactive soil-bentonite and apply bentomat and reactive mat are carried out under the low and high water pressure. According to test result, additional amount of bentonite decreases the coefficient of permeability up to the bentonite mixture ratio of 15%. Therefore, the permeability test for landfill liner's indicated that the use of general water would be in more safe side because the liner system show low permeability duet decrease effect of porous by suspended soild(SS). The permeability of leachate for Zeolite mixture ratio 0, 5, 10% with bentonite mixture ratio 15% showed negligible variation in the permeability with general water. Therefore, Zeolite could be used as a successful that is available purification material for the treatment of leachate, without changing the of landfill liners. Also odious smell could be removed by adding smell amount of Zeolite to the leachate. It was revealed that the bentomat and reactive mat installed in soil-bentonite layer effectively improved the permeability as well as purification of the leachate.

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Multiobjective Optimal Reactive Power Flow Using Elitist Nondominated Sorting Genetic Algorithm: Comparison and Improvement

  • Li, Zhihuan;Li, Yinhong;Duan, Xianzhong
    • Journal of Electrical Engineering and Technology
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    • v.5 no.1
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    • pp.70-78
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    • 2010
  • Elitist nondominated sorting genetic algorithm (NSGA-II) is adopted and improved for multiobjective optimal reactive power flow (ORPF) problem. Multiobjective ORPF, formulated as a multiobjective mixed integer nonlinear optimization problem, minimizes real power loss and improves voltage profile of power grid by determining reactive power control variables. NSGA-II-based ORPF is tested on standard IEEE 30-bus test system and compared with four other state-of-the-art multiobjective evolutionary algorithms (MOEAs). Pareto front and outer solutions achieved by the five MOEAs are analyzed and compared. NSGA-II obtains the best control strategy for ORPF, but it suffers from the lower convergence speed at the early stage of the optimization. Several problem-specific local search strategies (LSSs) are incorporated into NSGA-II to promote algorithm's exploiting capability and then to speed up its convergence. This enhanced version of NSGA-II (ENSGA) is examined on IEEE 30 system. Experimental results show that the use of LSSs clearly improved the performance of NSGA-II. ENSGA shows the best search efficiency and is proved to be one of the efficient potential candidates in solving reactive power optimization in the real-time operation systems.

Reactive Power Control of Single-Phase Reactive Power Compensator for Distribution Line (배전선로용 단상 무효전력 보상기의 무효전력제어)

  • Sim, Woosik;Jo, Jongmin;Kim, Youngroc;Cha, Hanju
    • The Transactions of the Korean Institute of Power Electronics
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    • v.25 no.2
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    • pp.73-78
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    • 2020
  • In this study, a novel reactive power control scheme is proposed to supply stable reactive power to the distribution line by compensating a ripple voltage of DC link. In a single-phase system, a magnitude of second harmonic is inevitably generated in the DC link voltage, and this phenomenon is further increased when the capacity of DC link capacitor decreases. Reactive power control was performed by controlling the d-axis current in the virtual synchronous reference frame, and the voltage control for maintaining the DC link voltage was implemented through the q-axis current control. The proposed method for compensating the ripple voltage was classified into three parts, which consist of the extraction unit of DC link voltage, high pass filter (HPF), and time delay unit. HPF removes an offset component of DC link voltage extracted from integral, and a time delay unit compensates the phase leading effect due to the HPF. The compensated DC voltage is used as feedback component of voltage control loop to supply stable reactive power. The performance of the proposed algorithm was verified through simulation and experiments. At DC link capacitance of 375 uF, the magnitude of ripple voltage decreased to 8 Vpp from 74 Vpp in the voltage control loop, and the total harmonic distortion of the current was improved.

Dyeing Properties of Acid and Reactive Dye for Super Soft Angora / PET, Nylon Blended Fabric (앙고라 섬유소재 / PET, Nylon 교직물의 염착 특성 : 산성염료와 반응성염료의 적용특성)

  • Kim, Young-Sung;Lee, Seok-Jang;Son, Young-A
    • Textile Coloration and Finishing
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    • v.22 no.4
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    • pp.332-340
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    • 2010
  • Nowadays natural textile materials should cope with the global warming. Soft, thin and light angora fibers which have two components. One is spiky hair and the other is soft hair. The spiky hairs have a disadvantage of pilling out. The soft hairs have promising properties comparable to cashmere goat hairs, which is cheap compared to very expensive cashmere goat hairs. In this study, we investigated the dyeing properties of angora/PET, Nylon blend fabrics to acid dyes and reactive dyes including various series of acid dyes and reactive dyes for the dyeing of the blended super soft angora fabrics and their potential for deep shade dyeing effects. Our focus is to get a relation between various kind of blend and their dyeability.

Novel control algorithm for smart PCS with harmonics and reactive power compensation (고조파와 무효전력 보상기능을 가지는 Smart PCS의 새로운 제어 알고리즘)

  • Seo, Hyo-Ryong;Jang, Seong-Jae;Park, Sang-Soo;Kim, Sang-Yong;Kim, Gyeong-Hun;Park, Min-Won;Yu, In-Keun
    • Proceedings of the KIEE Conference
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    • 2009.07a
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    • pp.1053_1054
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    • 2009
  • A significant number of renewable energy systems have been connected to the grids as supplement power source. The renewable energy systems require control algorithm to maintain the power-supply reliability and quality. This paper proposes a novel control algorithm for smart Power Conditioning System (PCS) with harmonics and reactive power compensation. The smart PCS is used to feed Photovoltaic (PV) power to utility and compensate harmonics and reactive power at the same time. The experimentation is carried out on the proposed grid-connected PV generation system, and controlled by digital signal processor. The grid-connected PV generation system injects PV energy into the grid and performs as Active Filter (AF) and Static Synchronous Compensator (STATCOM) without additional devices. The experiment results show that the proposed control algorithm is effective for smart PCS with harmonics and reactive power compensation.

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AN APPLICATION OF INTERPOLATION TECHNIQUE WITH OPTIMUM PATTERN TO VOLTAGE - REACTIVE POWER CONTROL OF POWER SYSTEM (전력계통 전압 - 무효전력제어에의 최적 패턴을 이용한 내삽기법의 적용)

  • Park, Young-Moon;Lee, Jeong-Ho;Yoon, Man-Chul;Kwon, Tae-Won
    • Proceedings of the KIEE Conference
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    • 1992.07a
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    • pp.214-217
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    • 1992
  • This paper introduces a new methodology to apply the interpolation technique wi th optimum pattern to voltage-reactive power control of power system. The conventional tool for the optimal operation of power system is Optimal Power Flow(OPF) by standard optimization techniques. The achievement of solution through OPF programs has a defect of computation time, so that it is impossible to apply the OPF programs to the real-time control area. The proposed method presents a solution in a short period of time and an output with a good accuracy. The optimum pattern is a set of input-output pairs, where an input is a load level and a type of outage and an output is the result of OPF program corresponding to the input. The output in the OPF represents control variables of voltage-reactive power control. The interpolation technique is used to obtain the solution for an arbitrary input. As a result, the new technique helps operators in the process of the real-time voltage-reactive power control in both normal and emergency operating states.

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Development of a Hydroponic Recycle System using the Visible Light-reactive Titanium Dioxide Photocatalyst for Sterilization of Nutrient Solution(I) - Determination of factors - (가시광 감응형 광촉매에 의한 수경재배용 배양액의 재이용 살균시스템 개발(I) - 광촉매 필터 요인시험 -)

  • Chung, Sung-Won;Ha, Yu-Shin;Lee, Jong-Won;Park, Jong-Min;Kwon, Soon-Hong;Lee, Ki-Myung
    • Journal of Biosystems Engineering
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    • v.35 no.6
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    • pp.420-425
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    • 2010
  • We produced a basic system of sterilization of nutrient solution based on the characteristics of coated filter with the visible light-reactive titanium oxide photocatalyst according to the findings of the first stage. We developed a model system with a proper number and arrangement of filter elements, the visible light-reactive titanium oxide photocatalyst according to findings from the basic performance test. Main results of this study were as followers; The ceramic filters showed the best performance of sterilization of nutrient solution. The visible light-reactive titanium oxide photocatalyst sterilized more effectively the nutrient solution under the sunlight than UV light. The sterilization performance by passing repeatedly through a few filter was more efficient than that by treating simultaneously with a large number of filters. The filter with 15ppi in pore size, 20 mm in thickness, and 3 layers in titanium oxide coating was desirable in the intensity and sterilization performance.

A Novel Anti-Islanding Method for Utility Interconnection of Distributed Power Generation Systems

  • In-Ho
    • KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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    • v.4B no.4
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    • pp.217-224
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    • 2004
  • A novel anti-islanding method for the distributed power generation system (DPGS) is proposed in this paper. Three different islanding scenarios are explored and presented based on the analysis of real and reactive power mismatch. It is shown via investigation that islanding voltage is a function of real power alone, where its frequency is a function of both real and reactive power. Following this analysis, a robust anti-islanding algorithm is developed. The proposed algorithm continuously perturbs ($\pm$5%) the reactive power supplied by the DPGS while simultaneously monitoring the utility voltage and frequency. In the event of islanding, a measurable frequency deviation takes place, upon which the real power of the DPGS is further reduced to 80%. A drop in voltage positively confirms islanding and the DPGS is then safely disconnected. This method of control is shown to be robust: it is able to detect islanding under resonant loads and is also fast acting (operable in one cycle). Possible islanding conditions are simulated and verified through analysis. Experimental results on a 0.5kW fuel cell system connected to a utility grid are discussed.

Operation Scheduling System for Hull Block Fabrication in Shipbuilding using Genetic Algorithm (유전 알고리즘을 이용한 선각 가공 작업일정계획 시스템의 개발에 관한 연구)

  • Cho, Kyu-Kab;Kim, Young-Goo;Ryu, Kwang-Ryel;Hwang, Jun-Ha;Choi, Hyung-Rim
    • IE interfaces
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    • v.11 no.3
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    • pp.115-128
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    • 1998
  • This paper presents a development of operation scheduling and reactive operation scheduling system for hull fabrication. The methodology for implementing operation scheduling system is HHGA(Hierarchical Hybrid Genetic Algorithm) which exploits both the global perspective of the genetic algorithm and the rapid convergence of the heuristic search for operation scheduling. The methodology for the reactive operation scheduling is the revised HHGA which consists of manual schedule editor for occurrence of exceptional events and the revised scheduling method used in operation scheduling. As the results of experiment, it has been confirmed that HHGA is able to search good operation scheduling within reasonable time, and the revised HHGA is able to search load-balanced reactive operation scheduling with minimum changes of initial operation schedule within short period of time.

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