SUMMARYThis paper presents a multibranch exchange method for reconfiguration of distribution systems to reduce their line losses. In this method several switches are closed and opened simultaneously in each branch exchange operation to expand the search neighborhood. The switches to be closed are selected as the intermediate systems will be meshed configuration. Sequential branch opening method can be applied to open the switches to obtain the radial configuration efficiently. Test examples show the effectiveness of the proposed method in the case of double branch exchange.
This p a p er p ur p oses a short circuit current estimation method using phasor measurement unit (PMU) measurements (synhcrophasors, hereafter called as phasors) of voltages and currents obtained during normal load variation. The method follows the basic concept of representing the source side of power system by an equivalent circuit with a voltage behind back impedance and employs a set of voltage and current phasors measured at substations over a certain p eriod. In order to improve an accuracy of the proposed estimation method, the concept of using a difference between the two consecutive phasors is introduced. Furthermore, to make the method applicable to a real world system, the estimation process is augmented by implementing a reference phasor concept to remove the effects of system wide frequency variations and a filtering process to filter out the outlier phasors. Finally, the validity and effectiveness of the purposed methods were checked and confirmed using field tests.Index Terms--Field testing, least square method, normal load variation, outlier filter, phasor measurement unit (PMU), short circuit current, short circuit impedance, reference phasor, two consecutive phasors difference based approach.
SUMMARY
This paper proposes estimation methods for short circuit currents using phasor measurement unit (PMU) measurements (phasors). The methods follow the basic notion of representing the source side of a power system by an equivalent circuit with a voltage behind a back impedance, and employ a set of voltage and current phasors measured at substations during the normal variation of loads in their estimation. In order to improve the estimation accuracy of the proposed methods, the concept of using the changes between consecutive phasors is introduced. Furthermore, to make the methods applicable to a real‐world system, the concept of a reference phasor, used to remove the effects of system‐wide frequency variations and a filtering process to filter out the outlier phasors, is proposed and implemented. The validity and effectiveness of the proposed methods were checked and confirmed through experiments and field tests.
SUMMARYThis paper proposes estimation methods for short circuit currents using phasor measurement unit (PMU) measurements (phasors). The methods follow the basic notion of representing the source side of a power system by an equivalent circuit with a voltage behind a back impedance, and employ a set of voltage and current phasors measured at substations during the normal variation of loads in their estimation. In order to improve the estimation accuracy of the proposed methods, the concept of using the changes between consecutive phasors is introduced. Furthermore, to make the methods applicable to a real-world system, the concept of a reference phasor, used to remove the effects of system-wide frequency variations and a filtering process to filter out the outlier phasors, is proposed and implemented. The validity and effectiveness of the proposed methods were checked and confirmed through experiments and field tests. C⃝ 2014 Wiley Periodicals, Inc. Electr Eng Jpn, 188(4): 44-53, 2014; Published online in Wiley Online Library (wileyonlinelibrary.com).
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