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A new circuit of parallel-type voltage sag compensator is proposed in this paper. The proposed voltage sag compensator can reduce the necessary capacity of the energy storage capacitor for compensation by boost-type power factor correction rectifier charging the capacitor during a voltage sag. As a result the proposed system can reduce the size and maintenance of the apparatus. Copyright © 2004 Wiley Periodicals, Inc. This paper shows the principle and control system of the proposed circuit. Compensation characteristics were demonstrated by simulation and experiment. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 159(2): 19–33, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20261

This paper presents high-order harmonic resonance phenomena of voltage-sourced converters (VSC). When a voltage-sourced converter is connected to a power system with cables, there is a possibility that minute high-order harmonic voltages of a voltage-sourced converter are magnified by a series resonance and a parallel resonance, and high-order harmonic resonance phenomena are determined by this study. The cause of high-order harmonic resonance phenomena is investigated and elucidated by the analysis using EMTP. In addition, it is verified that high-order harmonic resonance phenomena occur as a practical matter. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 150(3): 26–35, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20054

This paper presents a new concept for back-to-back (BTB) dc systems. The main feature of the proposed BTB is referred to as “massively parallel.” This massively parallel BTB system consists of a number of small or mediumcapacity inverter units that are connected in parallel. The concept of transmission power control using the massively parallel BTB is investigated using MATLAB for a case where a fault occurs. In addition, a method for modeling the proposed BTB in EMTP is investigated. The work presented in this paper shows that the proposed BTB system is very promising for large power system applications because the losses of the system are very small compared to conventional BTB using VSC (voltage source converter). The massively parallel BTB can keep operating even if an inverter unit fails, thus improving overall power transmission capability. © 2001 Scripta Technica, Electr Eng Jpn, 138(3): 34–42, 2002