A Modular Three-Phase Voltage Regulator With Fictitious DC-Link

Maoh-Chin Jiang,Yi-Ru Jiang,Tai-Chun Liu 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

A modular three-phase voltage regulator with a fictitious dc-link is proposed. The proposed scheme is the combination of three single-phase modules while each one of the single-phase module is a three-leg ac voltage regulator. Therefore, the proposed voltage regulator reduces the number of main switches and compensates the voltage of each phase independently. Furthermore, a small film ac capacitor is used to replace the electrolytic capacitor, which not only reduce the size of the dc link capacitor and the stress of the switches but also increase the lifetime of the voltage regulator. The proposed scheme can compensate the voltage disturbance such as under-voltage, over-voltage, voltage sag, voltage swell, three-phase voltage unbalance and three-phase load unbalance effectively. Besides, there are several advantages of this structure, for instance: simple system-configuration, rapid voltage-compensation, easy setup-maintenance and decreasing the production cost while increasing the system power density. Eventually, some experimental results are provided to illustrate the steady-state characteristics and transient responses of the proposed modular three-phase voltage regulator.

Single-Phase Z-Source AC/AC Converter with Wide Range Output Voltage Operation

Minh-Khai Nguyen,Young-Gook Jung,Young-Cheol Lim 전력전자학회 2009 JOURNAL OF POWER ELECTRONICS Vol.9 No.5

A new type of single-phase Z-source AC/AC converter based on a single-phase matrix converter is proposed in this paper. The proposed single-phase Z-source AC/AC converter has unique features; namely that the output voltage can be bucked and in-phase/out-of-phase with the input voltage; that the output voltage can be boosted and in-phase/out-of-phase with the input voltage. The converter employs a safe-commutation strategy to conduct along a continuous current path, which results in the elimination of voltage spikes on switches without the need for a snubber circuit. The operating principles of the proposed single-phase Z-source AC/AC converter are described, and a circuit analysis is provided. To verify the performance of the proposed converter, a laboratory prototype based on a TMS320F2812 DSP was constructed. The simulation and the experimental results verified that the output voltage can be bucked-boosted and in-phase with the input voltage, and that the output voltage can be bucked-boosted and out-of-phase with the input voltage.

Single-Phase Z-Source AC/AC Converter with Wide Range Output Voltage Operation

Nguyen, Minh-Khai,Jung, Young-Gook,Lim, Young-Cheol The Korean Institute of Power Electronics 2009 JOURNAL OF POWER ELECTRONICS Vol.9 No.5

A new type of single-phase Z-source AC/AC converter based on a single-phase matrix converter is proposed in this paper. The proposed single-phase Z-source AC/AC converter has unique features; namely that the output voltage can be bucked and in-phase/out-of-phase with the input voltage; that the output voltage can be boosted and in-phase/out-of-phase with the input voltage. The converter employs a safe-commutation strategy to conduct along a continuous current path, which results in the elimination of voltage spikes on switches without the need for a snubber circuit. The operating principles of the proposed single-phase Z-source AC/AC converter are described, and a circuit analysis is provided. To verify the performance of the proposed converter, a laboratory prototype based on a TMS320F2812 DSP was constructed. The simulation and the experimental results verified that the output voltage can be bucked-boosted and in-phase with the input voltage, and that the output voltage can be bucked-boosted and out-of-phase with the input voltage.

동적전압보상기의 전압제어를 위한 PLL 방식의 개선

김병섭(Byong-Seob Kim),최종우(Jong-Woo Choi) 대한전기학회 2009 전기학회논문지 Vol.58 No.5

Dynamic voltage restorer (DVR) is now more preferable enhancement than other power quality enhancement in industry to reduce the impact of voltage faults, especially voltage sags to sensitive loads. The main controllers for DVR consists of PLL(phase locked loop), compensation voltage calculator and voltage compensator. PLL detects the voltage faults and phase. Compensation voltage calculator calculates the reference voltage from the source voltage and phase. With calculated compensation voltage from PLL, voltage compensator restores the source voltage. If PLL detect ideal phase, compensation voltage calculator calculates ideal compensation voltage. Therefore, PLL for DVR is very important. This paper proposes the new method of PLL in DVR. First, the power circuit of DVR system is analyzed in order to compensate the voltage sags. Based on the analysis, new PLL for improving transient response of DVR is proposed. The proposed method uses band rejection filter (BRF) at q-axis in synchronous flame. In order to calculate compensation voltage in commercial instruments, the PQR theory is used. Proposed PLL method is demonstrated through simulation using Matlab-Simulink and experiment, and by checking load voltage, confirms operation of the DVR.

3상 4선식 저압 배전선로에서 선형 및 비선형 부하의 사용시 전압 불평형률 비교 분석

김종겸(Jong-Gyeum Kim),김지명(Ji-Myeong Kim) 대한전기학회 2017 전기학회논문지 Vol.66 No.3

In the three-phase four-wire low-voltage power distribution equipment, single-phase and three-phase load have been used mainly mixed. Also linear and nonlinear loads have been used together in the same conditions. In a three-phase four-wire distribution line, the current distribution of three-phase linear load is almost constant in each phase during driving or stopping, but the single-phase load is different from each other for each phase in accordance with the operation and stop. So that the voltage unbalance is caused by the current difference of each phase. In the three-phase four-wire distribution system, non-linear load is used with linear load. The presence of single-phase nonlinear loads can produce an increase in harmonic currents in three-phase and neutral line. It can also cause voltage unbalance. In the present study, we analyzed for the voltage unbalance fluctuations by the operation pattern of the single and three-phase linear and non-linear load in three-phase four-wire low voltage distribution system.

A Study on the Reliability of DVR in a 3-Phase Phase-Controlled Rectifier

Woo-Hyun Kim,Chul-Woo Park 한국조명·전기설비학회 2012 조명·전기설비학회논문지 Vol.26 No.11

This study investigated the relationship between the response time of DVR (Dynamic Voltage Restorer) and the possible compensation range for voltage dips by the DVR system which protects the 3-phase phase-controlled rectifier from said dips. As a result, the permissible range of voltage dip is presented in a 3-phase phase-controlled rectifier. When the DVR compensates for voltage dip, the range of voltage dip can be compensated according to the DVRs response time. Using the proposed method, DVR response time can be determined from the parameters of the 3-phase phase-controlled rectifier and the possible compensatory range of voltage dip, while at the same time it is possible to use a control system having an appropriate speed. Therefore, the use of excessively fast equipment can be avoided, improving the stability of the overall system. The reliability of the DVR concerning the 3-phase phase-controlled rectifier can be verified by simulation.

A Novel Method for Compensating Phase Voltage Based on Online Calculating Compensation Time

Mingyu Wang,Dafang Wang,Chuanwei Zhou,Xiu Liang,Guanglin Dong 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.2

Dead time and the nonideal characteristics of components all lead to phase voltage distortions. In order to eliminate the harmful effects caused by distortion, numerous methods have been proposed. The efficacy of a method mainly depends on two factors, the compensation voltage amplitude and the phase current polarity. Theoretical derivations and experiments are given to explain that both of these key factors can be deduced from the compensation time, which is defined as the error time between the ideal phase voltage duration and the actual phase voltage duration in one Pulse Width Modulation (PWM) period. Based on this regularity, a novel method for compensating phase voltage has been proposed. A simple circuit is constructed to realize the real-time feedback of the phase voltage. Utilizing the actual phase voltage, the compensation time is calculated online. Then the compensation voltage is derived. Simulation and experimental results show the feasibility and effectivity of the proposed method. They also show that the error voltage is decreased and that the waveform is improved.

A Novel Method for Compensating Phase Voltage Based on Online Calculating Compensation Time

Wang, Mingyu,Wang, Dafang,Zhou, Chuanwei,Liang, Xiu,Dong, Guanglin The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.2

Dead time and the nonideal characteristics of components all lead to phase voltage distortions. In order to eliminate the harmful effects caused by distortion, numerous methods have been proposed. The efficacy of a method mainly depends on two factors, the compensation voltage amplitude and the phase current polarity. Theoretical derivations and experiments are given to explain that both of these key factors can be deduced from the compensation time, which is defined as the error time between the ideal phase voltage duration and the actual phase voltage duration in one Pulse Width Modulation (PWM) period. Based on this regularity, a novel method for compensating phase voltage has been proposed. A simple circuit is constructed to realize the real-time feedback of the phase voltage. Utilizing the actual phase voltage, the compensation time is calculated online. Then the compensation voltage is derived. Simulation and experimental results show the feasibility and effectivity of the proposed method. They also show that the error voltage is decreased and that the waveform is improved.

전압 불평형에 의한 전력 변동 분석

김종겸(Jong-Gyeum Kim),박영진(Young-Jeen Park),김지명(Ji-Myeong Kim) 한국조명·전기설비학회 2017 조명·전기설비학회논문지 Vol.31 No.3

Voltage unbalance is mainly defined as the ratio of the negative sequence voltage to the positive sequence voltage. Voltage unbalance is generated by the unbalance of power fluctuation or load in the distribution line. If the magnitude and phase of the voltage on the supply side change due to a change in the single-phase load in a 3-phase 4-wire system where a single-phase load and a three-phase load are used together, a voltage unbalance will occur. Current unbalance can be high even at the lower voltage unbalance. Voltage and current unbalance are closely related to the power unbalance. Power unbalance is also related to load unbalance and can have a significant impact on the operating characteristics of the load In this paper, we analyzed for the load unbalance and power changes under the symmetric and asymmetric voltage unbalance.

Voltage balance strategy for DC‑port failures of three‑phase cascaded H‑bridge rectifiers based on negative sequence current injection

Xiaohan Liu,Xiao Liang,Kaiyue Gong,Siqi An,Xu Peng,Jun Cai,Xinyu Zhu,Chao Zhou 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.8

The three-phase cascaded H-bridge rectifier (CHBR) is widely used in high power and high voltage applications. This paper focuses on the load removed from the DC port of a three-phase CHBR, which can cause single-phase DC-port voltage unbalance issues and three-phases DC-port voltage unbalance issues. This paper proposes a voltage balance control strategy based on negative sequence current injection for three-phase CHBR to deal with the unbalance problem. An individual DC-port voltage control strategy is designed to balance the DC-port voltage in the faulty phase. In addition, a negative sequence current injection control strategy is responsible for balancing the DC-port voltages in the three phase CHBR. The effectiveness and feasibility of the proposed voltage control strategy based on negative sequence current injection is verified by the experimental results.