Restraint method of voltage total harmonic distortion in distribution network by power conditioner systems using measured data from IT switches

Abstract

The amount of distributed generation (DG) such as photovoltaic systems and wind power generator systems installed in distribution systems has been increasing because of reduction of the effects on the environment. However, harmonic problems in the distribution system are a concern in the context of increased connection of DGs through inverters and the spread of power electronics equipment. This paper proposes a method for the restraint of voltage total harmonic distortion (THD) in a whole distribution network by active filter (AF) operation of multiple power conditioner systems (PCSs). It also proposes a method for determination of the optimal gain of AF operation so as to minimize the maximum value of voltage THD in the distribution network by real‐time feedback control with measured data from information technology (IT) switches. In order to verify the validity of the proposed method, numerical calculations are carried out using an analytical model of a distribution network of interconnected DGs with PCSs. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 182(3): 19–29, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22354

Improvement of Power Quality in Distribution System by Residential PV Systems

“…However, we confirmed in our previous studies on control using PCSs of residential PV systems that, if voltage distortion is suppressed only in feeders where PV systems are connected, the voltage distortion deteriorates in other feeders [9,13]. Specifically, we propose a method to improve power quality, in which voltage excursions are prevented and voltage imbalance is improved by power factor control using multiple PCSs, and moreover harmonics are suppressed in the entire system through filtering by taking advantage of excess capacity of PCSs.…”

“…It is also needed to set filter to minimize total harmonic distortion (THD). However, we confirmed in our previous studies on control using PCSs of residential PV systems that, if voltage distortion is suppressed only in feeders where PV systems are connected, the voltage distortion deteriorates in other feeders [9,13]. Thus, in this paper, we propose a method to determine PV interconnection power factor and filter gain for each phase by means of feedback control using information acquired from multiple IT switches mounted in the system.…”

“…(8)), and filter gain (K v ) is varied based on the calculated value so as to keep THD below the control target value [13]. Specifically, system THD is calculated from voltage data acquired by IT switches (Eq.…”

“…For example, output of PV and so on is unsteady, depending on weather conditions, which may result in system voltage excursion upon operation at power factor of 1, decline in voltage balance due to connection of single-phase residential PV systems. We have already addressed solving problems of voltage and frequency in an entire power system by using PV systems, without additional introduction cost [13,14]. Thus, it is said that protection and improvement of power quality is an increasingly urgent issue.…”

“…Nevertheless, even though voltage excursion at connection point is prevented by reactive power control, voltage troubles may remain at other locations, which need to be taken into account. We have already addressed solving problems of voltage and frequency in an entire power system by using PV systems, without additional introduction cost [13,14].…”