• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2009년도 제40회 하계학술대회
• /
• pp.444_445
• /
• 2009

A common approach to estimate long-term electric expansion plan used WASP package in Korea. But, this has a little problem for making input DG(Distributed Generation) data computer. This paper develops new program that take complementary measures for DG. Also, it is verified that this package can evaluate availability from the case studies. When this program cooperate with WASP, calculate good results creating long-term electric expansion plan.

• Journal of Electrical Engineering and Technology
• /
• 제8권5호
• /
• pp.1002-1011
• /
• 2013

This paper proposes the new adaptive protection algorithm for inverse-time overcurrent relays (OCRs) to ensure their proper operating time and protective coordination. The application of the proposed algorithm requires digital protection relays with microcontroller and memory. The operating parameters of digital OCRs are adjusted based on the available data whenever system conditions (system with distributed generation (DG)) vary. Moreover, it can reduce the calculation time required to determine the operating parameters for achieving its purpose. To verify its effectiveness, several case studies are performed in time-domain simulation. The results show that the proposed adaptive protection algorithm can keep the proper operating time and provide the protective coordination time interval with fast response.

• 조명전기설비학회논문지
• /
• 제26권1호
• /
• pp.44-53
• /
• 2012

This paper presents a method to calculate the area of vulnerability by using the impedance building algorithm. The installation of DG (Distributed Generation) is one of the countermeasures against voltage sags in power systems. In order to estimate the effect of the DG, the voltage sag assessment should be performed based on the area of vulnerability and system fault statistics. To determine the area of vulnerability, system impedance matrix should be calculated. The calculation of the impedance matrix of large systems is time-consuming task. This paper addresses an effective scheme to calculate the area of vulnerability and system impedance matrix.

• 전력전자학회:학술대회논문집
• /
• 전력전자학회 2012년도 전력전자학술대회 논문집
• /
• pp.256-257
• /
• 2012

This paper presents a new control strategy to improve voltage performance of distributed generation (DG) under nonlinear loads. The proposed voltage controller consists of a proportional-integral and a repetitive controller where the repetitive controller behaves as a bank of resonant controllers to compensate harmonic voltage drop on system impedance due to nonlinear load current. As a result, the voltage at the point of common coupling (PCC) of the DG is regulated to be sinusoidal waveform regardless of the presence of nonlinear loads. In order to validate the effectiveness of the proposed voltage controller, simulations are carried out using PSIM software and results are compared with those with the conventional PI controller.

• 전기학회논문지
• /
• 제60권12호
• /
• pp.2206-2214
• /
• 2011

LDC(Line Drop Compensation) is widely used in controlling ULTC(Under Load Tap Changer) output voltage at distribution substation. However, LDC may experience some difficulties in voltage control due to renewable energy resources and distributed generations. Therefore, more advanced voltage control algorithm is necessary to deal with these problems. In this paper, a modified voltage control algorithm for ULTC and DG is suggested. ULTC is operated with the voltages measured at various points in distribution system and prevents overvoltage and undervoltage in the distribution feeders. Reactive power controller in DG compensates the voltage drop in each distribution feeders. By these algorithms, the voltage unbalance between feeders and voltage limit violation will be reduced and the voltage profile in each feeder will become more flat.

• 전기학회논문지
• /
• 제66권2호
• /
• pp.300-304
• /
• 2017

Due to the introduction of various types of dispersed generations (DGs) with larger capacity in a power distribution system, the short-circuit current is expected to be increased, which more requires for the effective fault current limiting methods. As one of the promising countermeasures, the superconducting fault current limiter (SFCL) has been noticed. However, the decreased fault current by SFCL affects the operation of the overcurrent relay (OCR), representative protective device in a power distribution system. In this paper, the operation of the overcurrent relay due to the application of a SFCL in a power distribution system with DG linked by its bus line was analysed through the short-circuit tests. To analyze the effect of the SFCL application in a power distribution system with DG, the experimental simulated circuits were designed and the short-circuit tests for the power distributed system assembled with the DG, the OCR and the SFCL were carried out. Through the analysis on the short-circuit tests, the application of the SFCL in a power distribution system with DG could be confirmed to be contributed to the operational improvement of overcurrent relay.

• Journal of Power Electronics
• /
• 제15권5호
• /
• pp.1329-1337
• /
• 2015

By placing distributed generation power sources beside a big nonlinear load, these sources can be used as a power quality enhancer, while injecting some active power to the network. In this paper, a new scheme to use the distributed generation power source in both operation modes is presented. In this scheme, a fuzzy controller is added to adjust the optimal set point of inverter between compensating mode and maximum active power injection mode, which works based on the harmonic content of the nonlinear load. As the high order current harmonics can be easily rejected using passive filters, the DG is used to compensate the low order harmonics of the load current. Multilevel transformerless cascade inverters are preferred in such utilization, as they have more flexibility in current/voltage waveform. The proposed scheme is simulated in MATLAB/SIMULINK to evaluate the circuit performance. Then, a 1kw single phase prototype of the circuit is used for experimental evaluation of the paper. Both simulative and experimental results prove that such a circuit can inject a well-controlled current with desired harmonics and THD, while having a smaller switching frequency and better efficiency, related to previous 3-phase inverter schemes in the literature.

• 조명전기설비학회논문지
• /
• 제28권9호
• /
• pp.83-88
• /
• 2014

When DG interconnection into network is examined, details of the review are overvoltage, protective device malfunction, etc. In the case of protective device malfunction, replacing protective device into bi-directional protective device and installation NGR are the solution. Overvoltage at interconnection point occurs because the load is relatively less than DG output. When overvoltage at interconnection point occurs, DG interconnection is not permitted because this overvoltage affect other customers. Interconnection by installation new distribution line is one solution but it costs much money. Without installation new investment, change of NOP(Normal Open Point) position is a possible solution about DG interconnection into network.

• Journal of Electrical Engineering and Technology
• /
• 제5권4호
• /
• pp.530-537
• /
• 2010

By development of renewable energy and more efficient facilities in an increasingly deregulated electricity market, the operation cost of distributed generation (DG) is becoming more competitive. International environmental regulations of the leaking carbon become effective to reinforce global efforts for a low-carbon paradigm. Through increased DG, operators of DG are able to supply electric power to customers who are connected directly to DG as well as loads that are connected to entire network. In this situation, a community energy system (CES) with DGs is a new participant in the energy market. DG's purchase price from the market is different from the DG's sales price to the market due to transmission service charges and other costs. Therefore, CES who owns DGs has to control the produced electric power per hourly period in order to maximize profit. Considering the international environment regulations, CE will be an important element to decide the marginal cost of generators as well as the classified fuel unit cost and unit's efficiency. This paper introduces the optimal operation of CES's DG connected to the distribution network considering CE. The purpose of optimization is to maximize the profit of CES. A Particle Swarm Optimization (PSO) will be used to solve this complicated problem. The optimal operation of DG represented in this paper would guide CES and system operators in determining the decision making criteria.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2008년도 제39회 하계학술대회
• /
• pp.496-497
• /
• 2008

This paper presents development of the long and mid term power expansion planing for distributed generation. This planing model reflect WADE Economic Model's advantage that special quality of DG(Decentralized Generation) and WASP Model's advantage that special quality of CG(Centralized Generation) each other. Through these synergy, we develop better the Plan of Long and Mid Term Distributed Generation then existent model.