Mutsumi Aoki

Static capacitor control for hybrid type power quality conditioner

In recent years, the voltage rise at the end of distribution line and the increase of harmonic voltages has become to be greatly concerned because of extreme expansion of distributed generation (DG) systems and excessive amount of static capacitors (SCs) for improving power factor. For compensating leading current and harmonic currents from consumers, the hybrid type of power quality conditioner was proposed. The proposed system consists of a LC series circuit, a series transformer and a self-commutated converter in order to reduce the capacity of the converter than the conventional type of static synchronous compensators (STATCOMs) and active filters (AFs). This paper presents SC bank quantity control to expand the range of the compensating current and DC bus voltage control of the converter in the hybrid type power quality conditioner. In this study, the performance evaluations for the proposed conditioner in terms of the control of the harmful currents are presented by the various simulations.

Reaction of hydroxybenzyl alcohols under hydrothermal conditions

Under hydrothermal conditions, salicylic alcohol and p-hydroxybenzyl alcohol were transformed into phenol in high or moderate yields, whereas m-hydroxybenzyl alcohol and benzyl alcohol proved to be stable and remained almost intact.

Voltage regulation in distribution system using the combined DVR

In recent years, renewable energy system such as Photovoltaic generation system (PV) is widely introduced in distribution system. On the other hand, voltage deviation due to voltage fluctuation and unbalanced voltage caused by PV becomes serious problem. In order to mitigate those problems, the Combined type Dynamic Voltage Regulator (C-DVR) which consists of a step voltage regulator and AC chopper is the effective device. C-DVR can regulate line voltage continuously and quickly. This paper shows the effectiveness of C-DVR by the numerical simulation.

Effective Voltage Control by SVR to Reduce the Capacity of SVC using Solar Radiation Information with Real Time Simulator

With the increasing the number of Photovoltaic generators (PV) connected to distribution system (DS), several concerns such as rise and sudden change of voltage on distribution line are growing in Japan. Step Voltage Regulator (SVR) is well known as the one of voltage control equipment used in current DS. Meanwhile, SVR cannot regulate rapid voltage change because SVR has time delay against variation of voltage. In contrast, Static Var Compensator (SVC) is the effective device to control voltage changed rapidly. However, since the cost of SVC with large capacity is expensive, it is important to reduce the capacity of SVC in order to increase the introduction of SVC into power system. From this background, the novel control method of SVR using solar radiation information to reduce the capacity of SVC is proposed in this paper. The effectiveness of the proposed method is confirmed by numerical simulation with real time simulator.

Power Factor Control for Hybrid Type Power Quality Conditioner

In recent years, power quality in distribution system becomes to be greatly concerned. There are two power quality problems greatly. One is the voltage rise, the other is harmonics voltage. The voltage rise in distribution system is caused by leading current from Static Capacitors (SCs) which are widely installed at receiving points by consumers to improve power factor. Especially, the voltage rise is caused in light-load time, because of the excessive amount of SCs. On the other hand, the harmonic voltages are caused by nonlinear loads such as power electronics devices. Since harmonic currents from nonlinear loads flow through the line and transformers, the voltage is distorted. To improve those problems of power quality, Hybrid type Power Quality Conditioner (HyPQC) is proposed. HyPQC is consist of the power electronics converter and LC circuit, it could compensate the reactive current and harmonic currents from loads. In order to use for practical application, the experimental test should be performed. From this background, this paper presents the control algorithm to compensate the reactive current and harmonic currents in case of changing the loads. The simulation and experimental results are also presented using the proto type model.