• Journal of Electrical Engineering and Technology
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• 제6권3호
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• pp.375-383
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• 2011

This paper describes a real-time hardware simulator for a grid-tied Permanent Magnet Synchronous Generator (PMSG) wind power system, which consists of an anemometer, a data logger, a motor-generator set with vector drive, and a back-to-back power converter with a digital signal processor (DSP) controller. The anemometer measures real wind speed, and the data is sent to the data logger to calculate the turbine torque. The calculated torque is sent to the vector drive for the induction motor after it is scaled down to the rated simulator power. The motor generates the mechanical power for the PMSG, and the generated electrical power is connected to the grid through a back-to-back converter. The generator-side converter in a back-to-back converter operates in current control mode to track the maximum power point at the given wind speed. The grid-side converter operates to control the direct current link voltage and to correct the power factor. The developed simulator can be used to analyze various mechanical and electrical characteristics of a grid-tied PMSG wind power system. It can also be utilized to educate students or engineers on the operation of grid-tied PMSG wind power system.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2009년도 정기총회 및 추계학술대회 논문집
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• pp.185-187
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• 2009

This paper describes development of a hardware simulator for the PMSG wind power system. The simulator consists of a realistic wind turbine model using anemometer, vector drive, induction motor. The turbine model generates torque and speed signals for a specific wind turbine with real wind speed. The torque and speed signals are scaled down to fit for the input power of 3kW PMSG. The hardware simulator was developed through computer simulations, and the operation was confirmed by experimental works.

• 대한기계학회논문집B
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• 제27권7호
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• pp.938-947
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• 2003

In this paper, we derived the formula for estimating the power of the electric motors needed to operate the Decanter-type centrifuge. In the derivation of the formula the sludge-removal torque is to be supplied from the formula derived in the first paper. The intricate nature of the transmission mechanism in the planetary gear trains of the sludge-removal power and torque has been clarified in this second paper. In particular we considered two-motor system, where the main motor drives the machine while the differential-speed control motor plays the role of braking in adjusting the differential speed. Sample calculation for the specific design treated in the first paper showed that the selection criterion for the main motor depends on the lower limit of the differential speed; when the lower limit is set low, it should be selected based on the steadily operating power, while it should be selected based on the starting power when the lower limit is set high. The total power required by both the main motor and the differential-speed control motor increases as the differential speed is decreased. It is suggested that the power loss in the differential-speed control motor could be minimized by attaching an electric generator to it.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 춘계학술대회
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• pp.59-63
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• 2005

The 800-kW PM (permanent magnet) synchronous generator is developed as a wind power generator. The matching converter is designed to control the torque and power depending on the wind speed regime. The generator starts to generate the power at the speed of 9 rpm and the rated output is generated at the speed of 25 rpm. The rated output power of an inverter is 750 kW when the PM synchronous generator is delivering 800 kW to the inverter. The inverter is specially designed to perform the maximum power point tracking (MPPT) at the low wind speed regime that is typical wind environment in Korea. The inverter test was done with a 2 MW M-G system at KERI (Korea Electric Research Institute). The M-G set has a 2 MW motor driver and a 38:1 gear to match the speed between the motor and the PM generator. The torque simulating the wind is applied to the PM generator by a DC motor. The test results show the inverter efficiency of $94.3\%$ at the rated power generating condition. The measured values show that the MPPT algorithm is working well. Overall reliability will be verified through the long-term site test.

• 한국자기학회지
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• 제27권1호
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• pp.1-8
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• 2017

플라이휠 에너지 저장 장치(Flywheel Energy Storage System, FESS)은 회전 운동 에너지를 저장하는 플라이휠 부분과 저장된 회전 에너지를 전기 에너지로 변환시키는 전동기/발전기 부분으로 구성된다. 일반적으로 플라이휠의 회전축은 전동기 및 발전기의 회전축과 동축 일체형으로 연결되고, 이때 전동기 및 발전기의 전자기 토크특성에 따른 동특성 변화는 전체 플라이휠 에너지 저장 장치의 충방전 특성과 기계적인 출력에 영향을 미친다. 본 논문에서는 5[kWh] 급 플라이휠 에너지 저장 장치 용 3상 유도전동기의 설계방법과 회전자 슬롯 수 변화에 따른 토크리플 특성과 고조파 영향을 중점적으로 분석하였다. 먼저, 플라이휠 에너지 저장 장치의 용량과 관성 모멘트에 의한 회전운동에너지의 관계식으로부터 플라이휠 크기와 전동기의 회전자 크기를 산정하는 방법을 제안하였다. 또한 플라이휠 에너지 저장 장치의 회전축의 고속구동 조건을 반영하여, 고속운전 영역에서의 전동기 토크리플 저감을 위한 유도전동기 회전자 슬롯수를 선정하였다. 이로부터 본 논문에서는 전동기 회전축과 동축으로 구성된 플라이휠의 소음 진동을 줄이고 고효율 충방전 특성을 구현하고자 한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1296-1297
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• 2011

This paper deals with a power-hardware-in-the loop simulation (PHILS) of permanent magnet synchronous generator (PMSG) type wind power generation system (WPGS) using a real hardware which consists of a motor generator set with motor drive, real time digital simulator (RTDS), and back-to-back converter. A digital signal processor (DSP) controls the back-to-back converter connected between the back-to-back converter and the RTDS. The proposed PHILS can effectively be applied to demonstrate the operational characteristics of PMSG type WPGS under grid connection.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제51권8호
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• pp.467-474
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• 2002

In this paper, a wind power simulator is designed and implemented. To realize the torque of wind blade, a DC motor is used as a variable torque input device. An induction machine is used as a generator of which speed is controlled to maintain the optimal tip speed ratio during wind speed change. Input torque of system is controlled by armature current of DC motor and speed is controlled by generator control unit using field oriented control algorithm. Various control algorithms such as MPPT, soft start up, the simulator reactive power control, can be developed and tested using the simulator.

• Journal of Advanced Marine Engineering and Technology
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• 제16권4호
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• pp.50-59
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• 1992

The paper presents a digital speed control approach of induction motor systems by using a digital servo control method and a well-known second order differential equation as model. The basic concept of using the modeling equation stated in the above is induced from the control theory stand point such that we can describe usually the motor system connected by inverter, generator and load etc, just as a mechanical system to be controlled. The concept does not demand us the complicated vector-based modeling equation adopted in the traditional methods for the speed control of induction motor. Futhermore, the proposed speed control system can be treated as a single input and single output system. The effectiveness of the servo control system obtained by the above-mentioned design concept is illustrated by the experimental results in the presence of both step reference changes and load variations. It is observed from the experimental results that the steady state-error of the experimental set up becomes zero after some regulation time and the induction motor system is robust in spite of reference signal changes and load variations.

• 전기학회논문지
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• 제57권6호
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• pp.951-958
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• 2008

This paper describes development of hardware simulator for the PMSG wind power system, which was designed considering wind characteristic, blade characteristic and blade inertia compensation. The simulator consists of three major parts, such as wind turbine model using induction motor, PMSG generator, converter-inverter set. and control system. The turbine simulator generates torque and speed signals for a specific wind turbine with respect to given wind speed. This torque and speed signals are scaled down to fit the input of 2kW PMSG. The PMSG-side converter operates to track the maximum power point, and the grid-side inverter controls the active and reactive power supplied to the grid. The operational feasibility was verified by computer simulations with PSCAD/EMTDC, and the implementation feasibility was confirmed through experimental works with a hardware set-up.

• 동력기계공학회지
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• 제21권4호
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• pp.5-17
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• 2017

This study focuses on the application of the PEM Fuel Cell(PEMFC) hybrid system, which includes a regenerative braking system with supercapacitor(SC) and battery. The purpose of this study is to evaluate the characteristics of regenerative energy and to propose solutions to increase regenerative energy via vehicle simulation. To achieve this target, we set the rated motor speed to 3,000/2,500/2,000 rpm. Because the flywheel is directly connected to the motor, the generator activates regenerative braking by using the rotational momentum of the flywheel when the flywheel reaches the set speed after the motor stops. We could then measure the characteristics of regenerative braking of voltage, current, power, energy change, etc. Meanwhile, we calculate the storage efficiency of the SC or the battery. Our results show that the SC stores 18% of the regenerative energy, while battery stores 15% of the energy. Since the regenerative energy decreases with the decrease of the motor rotating speed that 5,027 J and 2,915 J are restored at 3,000 and 2,500 rpm, respectively. The experimental results also prove that regenerative braking energy is able to be obtained if and only if the speed of flywheel is over 2,500 PRM, and the efficiency of the system can be further improved.