• 전기의세계
• /
• 제14권3호
• /
• pp.10-17
• /
• 1965

This paper presents a method of the voltage-reactive power control in the long and short range operations and introduces a conception, "optimum control pattern." The optimum control pattern, aiming at the over-all system control, is defined as the optimum voltage distribution which minimizes the system operating cost under the conditions that the specified power be supplied and the system voltage be kept within the specified bounds. The following procedure was adopted to obtain this optimum pattern. In the first place, a power system was divided into three blocks, namely, load, substation and generator. Lagrange's, multiplier method is applied to each block in turn, paying attention only at the operating voltage distribution. Phase angles at each bus are then modified so that the continuity of active power is maintained. This procedure may be called "block relaxation method with Lagrange's multipliers." In a long range operation, this control pattern determines the optimum installation capacity of reactive power sources. In a short range operation, it also gives the reference state of real time control and the optimum switching capacity of reactive power souces. The real time control problem is also studied from the standpoint of cooperation of control devices such as generators, shunt capacitors, shunt reactors and ratio load controllers. A proposal for the real time control will contribute to the automation of power system operation in the near future. in the near future.

• 전력전자학회논문지
• /
• 제27권3호
• /
• pp.256-264
• /
• 2022

The frequency power control method (FCM) which has a wide operating frequency range is adopted for induction heating (IH) cooktops. When FCM is applied to the full-bridge series resonant converter (FB-SRC) based IH system, high-frequency switching of the inverter is required compared to the half-bridge SRC (HB-SRC)-based IH system. Therefore, the switching loss of the inverter increases, and applying FCM under the condition that the inverter operating frequency range is limited is difficult. Therefore, this paper proposes a control strategy with the phase shift power control method considering that limited frequency conditions are presented. Loss analysis following the control method is performed through simulation and mathematical analysis. In addition, the validity of the proposed control strategy is verified by analyzing the heating performance following the control method through the test results of the 3,200[W] prototype.

• Nuclear Engineering and Technology
• /
• 제53권3호
• /
• pp.851-859
• /
• 2021

Small PWR can be used for power generation and heating. Considering that small PWR has the characteristics of flexible operating conditions and complex operating environment, the controller designed based on single power level is difficult to achieve the ideal control of small PWR in the whole range of core power range. To solve this problem, a flexible switching controller based on fuzzy controller and LQG/LTR controller is designed. Firstly, a core fuzzy multi-model suitable for full power range is established. Then, T-S fuzzy rules are designed to realize the flexible switching between fuzzy controller and LQG/LTR controller. Finally, based on the core power feedback principle, the core flexible switching control system of small PWR is established and simulated. The results show that the flexible switching controller can effectively control the core power of small PWR and the control effect has the advantages of both fuzzy controller and LQG/LTR controller.

• 한국지열·수열에너지학회논문집
• /
• 제6권2호
• /
• pp.1-7
• /
• 2010

The objective of this study is to find the optimal control algorithm of a hybrid Plant, which is combined by renewable energy plant of the GSHP(Geothermal Source Heat Pump) and the normal plant (Chiller, boiler). The work presented in this study was carried out in the EnergyPlus(Version 2.0). The EnergyPlus was modified in order to simulate the hybrid plant. The plant system was controlled by the load-range-based operation in which schemes select a user specified set of equipment for each user specified range of a particular simulation condition. In the use of the load-range-based operation, four kind of control cases were defined and simulated in order to obtain the optimal control algorithm of the hybrid plant. The result showed that the Case 2 was the optimal control algorithm which used the GSHP as a base operating plant and the normal plant as an assistant operating plant. Even though the normal plant was operated in full load and the renewable energy plant of the GSHP was operated in partial load, the annual energy consumption of the normal plant was larger than that of the GSHP plant.

• Design & Manufacturing
• /
• 제11권2호
• /
• pp.29-36
• /
• 2017

In this study, the non-contact type bicycle generator system considering the recharge is developed to use the eco-friendly energy source when the bicycle is operating. The following three main factors are considered in this study. One of factors is that the intensity of the rotating magnet is in the range of 2,700~4,300 [Gause]. The next factor is that the separation distance of rotating magnet and bicycle rim is in the range of 1.5-3.0 mm. The last factor is that the pedaling speed is in the range of 55 RPM [Wheel speed 5.6Km]~150 RPM [Wheel speed 15.25Km] consirering with the 5 staged gear transmission. The obtained results are as followed. (1) The generator output voltage gradually increases from 3V to 10V with the pedaling speed increases, at the separation distance is less than 2.5 mm and the operating voltage of the LED lamp is generated at a pedaling speed of 60 RPM or more. (2) The output current of the generator increases from 20mA to 40mA with the pedaling speed increases, at a separation distance is less than 2.0 mm and the operating current of the LED lamp is generated at a pedaling speed of 60 RPM or more. (3) When the separation distance was 3.0 mm, the output voltage and current are significantly lower than those of the bicycle LED lamp is generated. (4) The charging time is expected to be 12.24 ~ 17.65 hours when the magnitude of the magnet is 3,400[Gauss] at a pedaling speed of 55 RPM or more. (5) As a result of this study, it is thought that the non-contact type bicycle generator system considering the recharge can replace the conventional friction power generation system.

• 한국전자파학회논문지
• /
• 제22권5호
• /
• pp.522-527
• /
• 2011

본 논문에서는 54 GHz 대역의 위상 고정 루프에서 사용되기 위한 Ring 발진기를 이용한 3 분주 주입 동기 주파수 분주기(Injection-Locked Frequency Divider: ILFD)를 0.13-${\mu}M$ Si RFCMOS 공정을 이용하여 설계, 제작한 결과를 보인다. 1.8 V의 공급 전압에 대해서 buffer단을 포함하여 70 mW의 전력을 소비하며, 입력 신호가 없을 때 0~1.8 V의 varactor 조정 전압 범위에 대하여 18.92~19.31 GHz에서 자유 발진(free-running oscillation)을 하였다. 0 dBm의 입력 전력에 대해서 1.02 GHz(54.82~55.84 GHz)의 동기 범위(locking range)를 가지며 varactor 조정(0~1.8 V)을 포함한 동작 범위(operating range)는 약 2.4 GHz(54.82~57.17 GHz)를 보였다. 제작된 회로의 크기는 측정 pad를 포함하여 0.42 mm${\times}$0.6 mm이며, pad를 제외한 실제 동작 영역의 크기는 0.099 mm${\times}$0.056 mm이다.

• 한국소음진동공학회논문집
• /
• 제20권5호
• /
• pp.502-509
• /
• 2010

A test facility which can simultaneously measure turbocharger operating condition variables and vibro-acoustic emission in the situations that are quite similar to real internal combustion engine operating conditions has been introduced. Using this facility, a new method sweeping from full open throttle to deep surge region along constant speed curves can be utilized instead of the stationary method that has been traditionally used to obtain turbocharger compressor maps. Data covering an extensive range of the compressor performance map have been collected and analyzed. An experimental study is performed to define a noise diagram that correlates vibro-acoustic measurements to aerothermodynamic operating conditions. An instrumentation set in the facility allows the automatic definition of the operating point on the turbine and compressor map of the turbocharger. Also, radiated sound pressure and casing vibration data corresponding to the point are obtained by a microphone in the vicinity of the compressor casing and an accelerometer on the casing. The major source(s) of noise at specific operating point on the map can be easily identified with these maps. Also, acoustic characteristics of a given turbocharger at the vicinity of the surge as well as in the surge are also defined. Finally, the possibility to define mild surge region of a turbocharger using vibro-acoustic measurements is studied.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
• /
• pp.125.2-125.2
• /
• 2010

In this paper, both theoretical and experimental investigations have been performed to examine the effects of key operating parameters on the cell performance of a DMFCs (i.e., methanol feed concentration and operating temperature). For experiment, the membrane electrode assemblies (MEAs) were prepared using a conventional MEA fabrication method based on a catalyst coated electrode (CCE) and tested under various cell temperatures and methanol feed concentrations. The polarization curve measurements were conducted using in-house-made $25cm^2$ MEAs. The voltage-current density data were collected under three different cell temperatures ($50^{\circ}C$, $60^{\circ}C$, and $70^{\circ}C$) and four different methanol feed concentrations (1 M, 2 M, 3 M, and 4 M). The experimental data indicate that the measured I-V curves are significantly altered, depending on these conditions. On the other hand, previously developed one-dimensional, two-phase DMFC model is simulated under the same operating conditions used in the experiments. The model predictions compare well with the experimental data over a wide range of these operating conditions, which demonstrates the validity and accuracy of the present DMFC model. Furthermore, both simulation and experimental results exhibit the strong influences of methanol and water crossover rates through the membrane on DMFC performance and I-V curve characteristics.

• 대한기계학회논문집B
• /
• 제22권12호
• /
• pp.1755-1762
• /
• 1998

In order to minimize emission of polychlorinated dibenzo dioxins and polychlorinated dibenzo furans (PCDD/PCDFs) from municipal solid waste incinerators, it is important to maintain optimized operating conditions along with the system modification/improvement. Operating conditions of MSW incinerator make very complicated influence on formation of PCDD/PCDFs in each unit apparatus. For revealing these influences, concentrations of PCDD/PCDFs are measured from the stack and from the fly ash, while monitoring the plant operating conditions. The effects are grouped into 3 main categories, combustion conditions, de Novo synthesis effects, and adsorption/destruction effects in the flue gas treatment system. Interpretation of the results showed that de Novo synthesis effect, reformation by metalic catalyst, especially Cu in fly ash in the temperature range of $250{\sim}500^{\circ}C$, is found to influence most dominantly on the concentration of PCDD/PCDFs. A plausible mathmatical model for predicting concentration of PCDD/PCDFs is proposed, and discussed.

• 대한기계학회논문집A
• /
• 제20권9호
• /
• pp.2744-2751
• /
• 1996

In case of limited power supply, a rotating shaft system may not reach its operating speed that is greater than its critical speed, but the speed oscillates with small ampllitude near critical speed. As a result, it is considered that the operating mode plays an important role in the smooth start of machines. In order to investigate the dynamic behaviors of the rotating shaft system at the beginning stage, one has derived the equations of motion whose degrees of freedom is three, two translations and one rotation. The simultaneous differential equations are numerically solved by using runge-Kutta method, and thus the small time step length could be required corresponding to the stability of solution. Three types of operating modes dependent upon the driving torque rate have been numerically investigated according to the maximum displacement of shaft center. The first type of relation is linear, the second type is composed of two linear curves recommended by machine manufacturer, and the last one is the proposed torque curve reflecting the frequency response curve of one degree of freedom system. For the second type of modes, it is found that the optimal range of intermediate speed to the critical speed lies between 0.8 and 0.9. In addition to that, the maximum displacement can be reduced more if the third type of mode is utilized.