• 대한전기학회논문지:전력기술부문A
• /
• 제54권5호
• /
• pp.251-258
• /
• 2005

Recently, the domestic and foreign power trends are the supply of high quality power and environment conservation technology based on the new energies development. So, the dispersed generation systems, such as photovoltaic, fuel cell, and battery are to be introduced in distribution systems. According to the situation change, power of high Quality and reliability are required in distribution systems with dispersed generation. Up to now, the voltage in distribution systems are regulated by ULTC of substation and pole transformer of primary feeders. These days, Step Voltage Regulator(SVR) is getting established at distribution feeders to regulate effectively voltage of primary ffeders that voltage drop exceeds $5\%$. But, because SVR is operated independently with ULTC of substation, SVR can not take play to its full effectivity. Under these circumstances, in order to deliver suitable voltages to as many customers as possible, new optimal voltage regulation algorithms are required in distribution system. So, this paper presents optimal voltage regulation algorithm to regulate voltage effectively for ULTC and SVR in distribution systems with dispersed generation systems.

• Journal of Power Electronics
• /
• 제18권5호
• /
• pp.1536-1544
• /
• 2018

The existing 24-pulse autotransformer rectifier unit (ATRU) needs interphase reactors for parallel work of the rectifier bridges, and its output voltage cannot be regulated. Aiming at these problems, a step-up and step-down asymmetrical 24-pulse ATRU is proposed in this paper. The connections and turns ratios among transformer windings are well designed. In addition, a 15-degree phase difference is formed between two of the 24 voltage vectors produced by the transformer, which makes the four rectifier bridge groups produce a 24-pulse DC voltage without interphase reactors. Meanwhile, by adding extended winding to each phase of the transformer, wide-range regulation of the ATRU output voltage can be realized, and the reasonable voltage regulation range is between 0.2 and 1.6. The superposition of the voltage vectors and the principle of the voltage regulation are analyzed in detail. Furthermore, the turns ratio of the windings, winding current, output voltage, and kilovolt-ampere rating are all derived. Finally, the simulations and experiments are carried out, and the correctness of the principle and theoretical analysis of the new 24-pulse ATRU are verified.

• 전력전자학회논문지
• /
• 제23권5호
• /
• pp.345-351
• /
• 2018

A distributed control method is proposed to improve the power sharing performance of bidirectional distributed generators and the voltage regulation performance of a DC bus in a DC microgrid. Voltage sensitivity analysis based on power flow analysis is conducted to analyze the structural characteristics of a DC microgrid. A distributed control method using a voltage sensitivity matrix is proposed on the basis of this analysis. The proposed method uses information received through the communication system and performs the droop gain variation method and voltage shift method without additional PI controllers. This approach achieves improved power sharing and voltage regulation performance without output transient states. The proposed method is implemented through a laboratory-scaled experimental system consisting of two bidirectional distributed generators, namely, a load and a non-dispatchable distributed generator in a four-bus ring-type model. The experimental results show improved power sharing accuracy and voltage regulation performance.

• 전기전자학회논문지
• /
• 제27권3호
• /
• pp.308-312
• /
• 2023

게이트 전류 감지 구조는 LDO 레귤레이터가 오버슈트 또는 언더슈트 상황 발생 시 출력전압의 레귤레이션을 보다 효과적으로 제어하기 위해 제안되었다. 기존의 전형적인 LDO 레귤레이터는 부하전류가 변화할 때 레귤레이션 전압 변화가 발생한다. 하지만 게이트 전류 감지 구조를 이용하여 패스 트랜지스터에 있는 게이트 단자 전류를 공급/방전 함으로 인해 패스 트랜지스터의 동작 속도를 더욱 향상시킬 수 있다. 게이트 전류 감지 구조를 이용한 LDO 레귤레이터의 입력전압은 3.3 V ~ 4.5 V 이며 출력 전압은 3 V이고 부하 전류는 최대 250 mA의 값을 갖는다. 시뮬레이션 결과, 부하 전류가 250 mA 까지 변화할 때 약 9 mV의 전압 변화 값을 확인하였다.

• 대한전기학회논문지
• /
• 제31권7호
• /
• pp.11-17
• /
• 1982

In this paper, a reliable and convenient evaluation method for the adequacy of any radial distribution line's voltage drop is proposed for improvement of the voltage regulation of the distribution line under operation. Using the voltage measurement of the first load branch point and the last point on the given distribution line its average line voltage drop and the line voltage drop variance by pure load variation are computed. And by these values and allowable or required line drop from proper voltage regulation view point, present adequency index and operation improvement index of the line drop are newly introduced for the evaluation of the given distribution line's voltage regulation. As a result of application to the 4 cases of study, the proposed method is proved to be reliable and convenient.

• 전력전자학회논문지
• /
• 제16권2호
• /
• pp.182-190
• /
• 2011

본 논문은 계통 전압 사고 상황에서 계통 연계형 풍력 발전 시스템이 만족시켜줘야 할 LVRT(Low Voltage Ride Through) 제어 전략을 제안한다. LVRT 규정은 계통 전압 사고 시 풍력 발전 시스템이 지켜야 할 부분들을 전압 감소율과 사고 시간에 대해 나타내고 있다. 특히 전압 감소율이 10% 이상일 경우에는 풍력 발전 시스템은 규정된 무효 전류를 전력 계통에 제공하여 계통 전압 확보에 이바지해야 한다. 본 논문에서의 LVRT 규정은 세계적으로 가장 엄격한 규정인, 독일 계통 연계 규정(German Grid Code)을 기준으로 하고 풀 스케일(Full-scale) 가변 속도 전력 변환 시스템을 고려하여 제어 전략을 수립한다. 본 LVRT 제어 전략은 계통 사고 시 LVRT 규정을 모두 만족시킴과 동시에 직류단 전압 제어의 추가적인 알고리즘으로 직류단 전압의 제어를 통하여 전체 풍력 발전 시스템의 전력 균형을 기할 수 있다. 3상 전압 지락 사고의 경우 계통으로의 전력 제어가 불가능하여 계통 측 컨버터가직류단 전압을 제어할 수 없으므로, 전력 제어의 기능을 발전기 측 인버터로 이행 시켜 상황에 따라 유연한 직류단 전압 제어가 가능함을 보였다. 시뮬레이션과 실험을 통해 LVRT 제어 전략의 타당성을 검증하였다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1996년도 하계학술대회 논문집 A
• /
• pp.447-449
• /
• 1996

The main objective of this paper is to increase the efficiency, to eliminate the harmonics wave and to acomplish the zero voltage regulation of the output voltage. To accomplish the goal, DC-to-DC converter model with ERS(Energy Recovery Snubber) is developed. And, to realize the detail purpose, we are used ZVS soft switching snubber, ripple steering filter and, function control law etc.. So, we presented to show superior operation of this convertor with the zero voltage regulation function.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2011년도 제42회 하계학술대회
• /
• pp.1111-1112
• /
• 2011

This paper investigated application of fractional-slot concentrated-winding axial flux permanent magnet machines for wind turbines. Design criteria of cogging torque and voltage regulation was firstly proposed for this kind of application. Fractional winding has small cogging torque which is highlight for wind turbines, but slot leakage inductance would increase voltage regulation, which is an important performance index of generators. By varying slot opening, cogging torque and slot leakage inductance could be adjusted. In this paper, cogging torque and inductances were calculated by both analytical and finite element methods. Voltage regulation was studied by two-axis model under unity-power-factor load and verified by transient finite element analysis.

• 한국정보통신학회논문지
• /
• 제8권5호
• /
• pp.1068-1073
• /
• 2004

전원장치의 소형화 핵심기술인 반도체 스위칭 기술을 이용하여 5 V/500 mA급 트랜스리스형 파워모듈(transless type power module)을 설계하였다. 파워 모들은 강압형 chopper 방식을 이용하였으며, 스위칭회로, 제어회로, 전압검출회로, 그리고 정전압 회로 등으로 구성되어 었다. 본 연구에서 설계한 스위칭 파워모듈은 0.2 V의 load regulation, 0.1 V의 line regulation, 85 mVp-p의 output ripple 전압, 64.7 kHz의 스위칭 주파수, 최대 58% 정도의 효율을 나타내었으며, 신뢰성 및 EMC 평가항목을 만족하였다.

• International Journal of Control, Automation, and Systems
• /
• 제3권spc2호
• /
• pp.308-314
• /
• 2005

Transient stabilization with voltage regulation is investigated for a synchronous generator when the mechanical power is perturbed to any unknown value within its physical bounds so that the operating point of the system shifts to an unknown point. An adaptive excitation controller is designed based on the backstepping method with tuning functions. It will be shown that the adaptive control law proposed can achieve the convergence of the system states to the new equilibrium point in correspondence with the real value of the unknown mechanical power and the regulation of the terminal voltage to the required value. Simulation results are given to demonstrate the effectiveness of the proposed controller for the transient stabilization and voltage regulation.