DCU 데이터를 이용한 Forward/Backward Sweep 기반 불평형 배전계통의 선로 파라미터 추정 방법

Abstract

Recently, as the technology of renewable energy has been developed and policies to support the supply of renewable energy are implemented, the supply of renewable energy is increasing. Accordingly, the connection of distributed energy resource (DER) based on renewable energy to the distribution system is increasing. DERs are installed near customers, thereby reducing transmission losses and improving reliability. However, it causes various problems, such as overvoltage due to reverse power flow and protection cooperation problems in case of failure. Therefore, advanced distribution management system(ADMS) was introduced to solve these problems. ADMS enables the stable and efficient operation of the distribution system through various applications such as real-time system analysis and facility remote monitoring and control. Most of ADMS applications are designed based on the distribution system network model. With the introduction of ADMS, the distribution system needs a more accurate network model. However, the network model of distribution system is not well built up. Therefore, methods for network model estimation using the history of voltage, active power, and reactive power acquired from remote meter reading facilities, such as advanced metering infrastructure (AMI) or data concentrator unit (DCU), which are widely spreading in distribution systems, are being studied. There are various methods for network model estimation using a remote meter reading device installed in the distribution system. One of the methods is to utilize micro phasor measurement units (μPMUs) for the line parameter estimation. However, the μPMU is an expensive facility, so that it requires a lot of cost to install μPMUs to the distribution system. Therefore, a non-PMU based method for the line parameter estimation has been recently proposed. The line parameters are estimated by using the history of active power, reactive power, and the voltage magnitude, which are measured by the remote meter reading facilities. However, the conventional non-PMU based method cannot estimate the mutual impedance, because the distribution system was modeled as a three-phase balanced system. However, the actual distribution system is an unbalanced system in which the effects of mutual impedances is not negligible. Therefore, in this dissertation, a new method to estimate the line parameters including mutual impedances is proposed. The proposed method for line parameter estimation utilizes DCU data and forward/backward sweep. We test the proposed method on IEEE 13 node test feeder and IEEE 123 node test feeder using actual load patterns. The results demonstrate that the proposed method can estimate the line parameters including mutual impedances with high accuracy.