• Journal of the Korean Solar Energy Society
• /
• v.25 no.4
• /
• pp.21-27
• /
• 2005

This paper summarizes the results of these efforts by offering a photovoltaic system structure in 50kW middle scale applications installed in Cho-sun University dormitory roof. The combination of photovoltaic system components are interconnected and system monitoring system will be summarized for the purpose of the increasing safety in this article. This paper describes configuration of utility interactive photovoltaic system which generated electric power supplies to dormitory. In order to installing the middle or large scale photovoltaic system, It must investigated the optimal design of system, compute quantity of power generation, economic rate of return and so on. In this paper represent 50kW utility photovoltaic system examination and developed simulation results. The performance of photovoltaic system has been evaluated and analyzed with simulation. The results obtained in this research will be much useful to prior investigation for installing utility interactive photovoltaic system.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.5 no.5
• /
• pp.467-474
• /
• 2000

This paper describes the development of 7he utility vehicle controller using combination system of battery and photovoltaic power for increasing operation time. In order to keep interchangeability, low cost and high performance, a separately excited DC Motor is controlled without velocity and current measurements by $\mu$-processor. For the parallel operation between the solar cell and battery, dc-dc converter is used, which is applied to the maximum power Point tracking(MPPT) and current control algorithm. By the simulation and experimental results of trial product, the vapidity of the proposed system is verified.

• Proceedings of the KIEE Conference
• /
• 2005.04a
• /
• pp.271-273
• /
• 2005

Islanding of PV systems occurs when the utility grid is removed but local sources continue to operate and provide power to local loads. Islanding is one of the serious problems in an electric power system connected with dispersed power sources. Also, this can present safety hazards and the possibility of damage to other electric equipments. If the real and reactive power of RLC load and PV system are closely matched, islanding phenomena can't be detected by the passive methods. Several active methods were proposed to detect islanding phenomena. The most effective method is SFS method which was suggested by Sandia National Laboratory. In this paper, a new anti-islanding algorithm is proposed and its validity is verified through simulation and experimental results for utility interconnection of PV system.

• Journal of Electrical Engineering and Technology
• /
• v.9 no.2
• /
• pp.721-725
• /
• 2014

In this paper, we propose a fast adaptive power allocation method for an orthogonal frequency division multiple access (OFDMA) system that employs an adaptive modulation and coding (AMC) scheme. The proposed scheme aims to reduce the calculation complexity of greedy adaptive power allocation (APA), which is known as the optimal algorithm for maximizing the utility argument of power. Unlike greedy APA, which starts power allocation from "0", the proposed algorithm initially allocates a certain level of power determined by the water-filling scheme. We theoretically demonstrate that the proposed algorithm has almost the same capability of maximizing the utility argument as the greedy APA while reducing the number of operations by 2M, where M is the number of AMC levels.

• Journal of Energy Engineering
• /
• v.8 no.1
• /
• pp.76-84
• /
• 1999

The demand of Small Self-generating System (SSS) including Small Cogeneration System (SCS) is constantly increasing with the need of electricity and/or thermal in office, hospital, hotel, and small factory, etc. It is especially recommended to operate SCS in the heat-following mode to maximize the efficiency of generator. In case of the heat-following mode SCS has got to be connected to distribution system so as to send surplus power to the utility or receive the short power from utility. But the interconnection of SSS with distribution system causes a few problems such as the bad power quality, and low security. If SSS is not promptly disconnected after faults occur (Islanding of SSS), it can not only damage equipment of utility and adjacent customers but also endanger life of human due to overvoltage or overcurrent. In this paper it has been deeply discussed if interconnection of engine self-generator/control system satisfies the protective requirement for SSS or not. 500 kW engine generator running in the Jodo island has been used to perform the analysis of interconnection.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.12 no.1
• /
• pp.81-88
• /
• 2007

In this paper, a new single-phase utility-interactive inverter system for residential power generation with fuel cell is proposed. The proposed inverter system is not only capable of working in both stand-alone and grid-connected mode, but also ensures smooth and automatic transfer between the two modes of operation. The proposed control method has little steady-state error and good transient response characteristic. Also, the control method can be implemented using low-cost, fixed point DSP since it has simpler structure, smaller amount of calculation, and smaller number of sensors. The controller for the proposed utility-interactive inverter system is described, and the validity is verified through simulation and experiment.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.28 no.4
• /
• pp.1-19
• /
• 2003

This paper studies power and rate control for data users on the forward link of CDMA system with two cells. The QoS for data users is specified by delay and error rate constraints as well as a family of utility functions representing system throughput and fairness among data users. Optimal power and rate allocation problem is mathematically formulated as a nonlinear programming problem, which is to maximize total utility under delay and error rate constraints, and optimal power and rate allocation scheme (OPRAS) is proposed to obtain a good solution in a fast time. Computational experiments show that the proposed scheme OPRAS works very well and increases total utility compared to the separate power and rate allocation scheme (SPARS) which considers each cell individually.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.8 no.2
• /
• pp.199-210
• /
• 2003

In this paper, the new Islanding detection method is studied for utility interactive photovoltaic system(UIPVS). It describes the brief of UIPV system and the features of islanding phenomenon. The new islanding detection method for improving the detection characteristics, HCIM(Harmonic Current Injection Method), is proposed and analyzed. The impedance curve of AC load is derived from the complex power equation for testing Islanding detection features. The proposed detection method and the derivation of islanding condition we verified by the simulation with ACSL and the laboratorial experiments.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2007.11a
• /
• pp.279-285
• /
• 2007

Since the residential load is an AC load and the output of solar cell is a DC power, the photovoltaic system needs the DC/AC converter to utilize solar cell. In case of driving to interact with utility line, in order to operate at unity power factor, converter must provide the sinusoidal wave current and voltage with same phase of utility line. Since output of solar cell is greatly fluctuated by insolation, it is necessary that the operation of solar cell output in the range of the vicinity of maximum power point. In this paper, DC/AC converter is three phase PWM converter with smoothing reactor. And then, feedforward control used to obtain a superior characteristic for current control and digital PLL circuit used to detect the phase of utility line.

• 한국신재생에너지학회:학술대회논문집
• /
• 2007.06a
• /
• pp.288-291
• /
• 2007

Since the residential load is an AC load and the output of solar cell is a DC power, the photovoltaic system needs the DC/AC converter to utilize solar cell. In case of driving to interact with utility line, in order to operate at unity power factor, converter must provide the sinusoidal wave current and voltage with same phase of utility line. Since output of solar cell is greatly fluctuated by insolation, it is necessary that the operation of solar cell output in the range of the vicinity of maximum power point. In this paper, DC/AC converter is three phase PWM converter with smoothing reactor. And then, feedforward control used to obtain a superior characteristic for current control and digital PLL circuit used to detect the phase of utility line.