• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.6
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• pp.123-128
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• 2021

As the spread of DC power distribution systems increases, the occurrence of failures and fire accidents are also increasing. In particular, the ESS fire accident, which is a component of the smart grid, and the fire accident of the solar power system, which is a direct current system, are caused by problems in the electrical connection between system components as the supply of new and renewable energy rapidly increases and old facilities increase. An arc that can cause a direct fire by releasing the induced light and heat has been pointed out as one of the causes of fire. Therefore, the problem of such an arc defect is that it is impossible to block an arc accident in advance with the existing overcurrent circuit breaker and earth leakage circuit breaker. In this paper, we intend to develop a test equipment that satisfies international standardization and to develop a DC arc generator to protect against failure and fire caused by arcing.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.7
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• pp.1176-1185
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• 2016

This paper proposes a new output voltage control scheme based on the SoC variation of the battery energy storage system (BESS) applicable for the stand-alone DC microgrid. The proposed control scheme provides relatively lower variation of the DC grid voltage than the conventional droop method. The performance of proposed control scheme was verified through computer simulations for a typical stand-alone DC microgrid which consists of BESS, photo-voltaic (PV) panel, engine generator (EG), and DC load. A scaled hardware prototype for the stand-alone DC microgrid with DSP controller was set up in the lab, and the proposed control algorithm was installed in the DSP controller. The test results were compared with the simulation results for performance verification and actual system implementation.

• Journal of Power Electronics
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• v.7 no.2
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• pp.97-108
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• 2007

This paper describes simple control structures for a vector controlled stand-alone induction generator (IG) for use under variable speeds. Different control principles, indirect vector control and deadbeat current control, are developed for a voltage source PWM converter and the three-phase variable speed squirrel-cage IG to regulate DC-link and generator voltages with a newly designed phase locked loop circuit. The required reactive power for the variable speed IG is supplied by means of a PWM converter and a capacitor bank to buildup the voltage of the IG without the need for a battery, to reduce the rating of the PWM converter while using only three sensors and to eliminate the harmonics generated by the PWM converter. These proposed schemes can be used efficiently for variable speed wind energy conversion systems. The measurements of the IG systems at various speeds and loads are given and show that these systems are capable of good AC and DC voltage regulation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.10a
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• pp.744-747
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• 2010

This paper presents a novel adaptive control method for DC-DC converters applied in PV generator systems. We derive an state-space average model of the converter system and then propose a adaptive control methodology to enhance transient response performance for time-varying PV systems. A well-knwon Lyapunov theory is utilized for constructing our control algorithm. Numerical simulation demonstrates reliability of our control methodology and its superiority by comparison to a traditional control strategy.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1339-1342
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• 2005

This paper presents a simple AC-DC power conditioner for a squirell-cage induction generator(IG) operating under variable shaft speeds. The necessary reactive power for the IG system is supplied by means of a capacitor bank and a voltage-source PWM converter. Using a capacitor bank to transfer the reactive power to the IG under the rated speed and no-load conditions starts the IG operation and reduces the PWM power converter size. A simple control compensating for changes in the electrical loads as well as the variation in speed was developed to regulate the voltages of the IG system by controlling the rotor flux through its reactive and active currents control implementation. This proposed power conditioning scheme can be used efficiently as a wind power generation system where the output voltage of the IG is maintained constant voltage despite the variable frequency and the DC bus voltage of the PWM converter can be used for either DC applications such as battery charging or AC power applications with 60/50 Hz by connecting a stand alone inverter. The experimental and simulated operating performance results of a 5 kW IG scheme at various speeds and leads are presented.

• Proceedings of the KIPE Conference
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• 2017.11a
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• pp.69-70
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• 2017

This paper presents design of control system for permanent magnet synchronous generator(PMSG). The gas engine make rotating mechanical energy from gas fuel energy. The rotor of synchronous generator is connected to axis of engine. And it converts the mechanical energy to the electrical energy. The control system of PMSG helps the electrical energy to flow to grid. the single phase pfc rectifier controls the DC-link voltage by controlling the current of filter inductor. If the DC-link voltage is higher than the voltage reference, the filter current could be controlled to flow to grid. The three phase inverter controls the stator current of generator. The direction of the current is controlled depends on motoring or generating mode. The feasibility of the grid-connected PMSG is verified by the experimental results with 1kW prototype.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.735-736
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• 2008

There are many equipments for the Short Circuit Test, for example Short Circuit Generator, Induction Motor, Sequence Timer, CLR, Back Up Breaker, Making Switch and Excitation Equipment etc. Gradually an allowable tolerance of the short circuit test voltage is become smaller by the standards for short circuit test. The excitation equipment of short circuit generator is very important for test voltage is adjusted by the excitation equipment. Especially the excitation equipment must be possessed character of exactitude, durability and inalterability because some times around 10,000 times opening and closing short circuit test is requested by clint, which must be done within one minute. The purpose of this study for function and operation of the excitation equipment which rated DC voltage is 1,000V, rated DC current is 300A, rated out put is 30kW and type is YNEX 97S-441/609, is to help operation of short circuit generator.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1731-1732
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• 2005

본 논문은 풍력발전기 안정된 출력발전을 위하여 풍력 동기발전기 여자기 설계에 중점을 두었다. 풍력발전기 최대 발전을 얻기 위해 동기발전기 속도제어와 여자제어가 필요하다. 속도제어에서 AC/DC 정류기는 전력 다이오드로 구성하고 DC/AC 인버터는 IGBT로 구성하였다. 여자제어 구성은 AC/DC는 전력 다이오드로 구성하고 DC단은 DC/DC 부스트로 구성하였다. 또한, 동기발전기 여자 제어기 제어신호에 동기발전기 출력 AC/DC의 전력과 동기발전기 속도로 적절하게 조절함으로서 안정되고 최대 출력이 되도록 하였다. 또한, 제안된 제어기가 우수한 성능을 보임을 시뮬레이션으로 증명하였다.

• Journal of the Institute of Convergence Signal Processing
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• v.11 no.3
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• pp.226-231
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• 2010

This paper proposes a new coding technique for constructing error correcting high rate DC-free multimode code using a generator matrix generated from a sparse parity-check matrix. The scheme exploits high rate generator matrixes for producing distinct candidate codewords. The decoding complexity depends on whether the syndrome of the received codeword is zero or not. If the syndrome is zero, the decoding is simply performed by expurgating the redundant bits of the received codeword. Otherwise, the decoding is performed by a sum-product algorithm. The performance of the proposed scheme can achieve a reasonable DC-suppression and a low bit error rate.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.7
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• pp.1059-1065
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• 2017

In this paper, the energy harvester with a piezoelectric materials is modeled as the electric equivalent circuit, and performances of a standard DC method and a Parallel-SSHI method are verified through experiment under variable force and load conditions. Piezoelectric generator consists of mass, damper and spring constant, and it is modeled by electrical equivalent circuit with RLC components. Standard DC and Parallel-SSHI are used as power conversion methods, and standard DC consists of full-bridge rectifier and smoothing capacitor. Parallel-SSHI method is composed of L-C resonant circuit, zero-crossing detector and full-bridge rectifier. In case of simulation under $100k{\Omega}$ load condition, the harvested power is $500{\mu}W$ in Standard DC and $670{\mu}W$ in Parallel-SSHI, respectively. In experiment, the harvested power under $100k{\Omega}$ load condition is $420{\mu}W$ in standard DC and $602{\mu}W$ in Parallel-SSHI. Harvested power of Parallel-SSHI is improved by approximately 40% more than that of standard DC method.