An impedance based method for distribution system monitoring

摘要

The main goal of this thesis is to propose a new monitoring technique for traditional distribution system with integration of renewable energy source. The traditional distribution network is primarily composed of radial feeders, designed for unidirectional power flow. Therefore, many operation regulation, protection and control system, in distribution network, are based on the radial distribution systems assumption.ududThe high penetration of the renewable energy sources, will clearly impact the distribution systems operation. Unlike other ways of electricity generation renewable energies initiate some challenges for grid operation. Intermittency of renewable energies sources, power system protection, stability, security, economic dispatch, optimal power flow are critical issues initiated by renewable energies penetration to power systems.ududIn addition, the renewable energy source output may exceed the consumed power during the day. Therefore, the direction of the power flow can be reversed during some periods. The high penetration of decentralized renewable sources will create a multidirectional power flow condition in the distribution grid, which was originally designed for unidirectional power flow only. Following of this reverse power flow, the distribution feeder voltage rises.ududIn this thesis the necessity of online monitoring system for important feeders in distribution system will be shown. It will be shown that the apparent impedance measured on the feeder has great capabilities for on line monitoring of distribution feeder.ududThe thesis establishes the steady-state mathematical model for defining the monitoring zone in R-X plane as the main contribution. It will be shown that the apparent impedance has a good potential for monitoring of feeder power factor, reverse and forward active and reactive power flow. In addition, it will be shown that complex power curve can be transferred to R-X plane to monitor the reactive power requirement regulation issued by utilities for RES integration.