A Monitoring Technique for Reversed Power Flow Detection With High PV Penetration Level

Abstract

Abstract-Theintegration of renewable energy resources (RESs) in power systems poses many research challenges. Research shows that the RES output may exceed the consumed power during the day. Consequently, the direction of the power flow on distribution lines can be reversed during some periods. As the voltage regulator is normally designed for unidirectional power flow, this may cause voltage violations on the distribution feeder. Therefore, most utilities try to set a penetration level (PL) limit for safe operation. On the other hand, time varying and unbalanced loading are the main characteristics of distribution systems. Moreover installation of intermittent and nondispatchable photovoltaic (PV) devices increases the control problems of distribution system. This paper presents an impedance-based monitoring method for detection of distribution system current behavior. It will be shown that by utilizing this monitoring technique, not only the small variation of PV PL can be easily detected, but also some fast transients such as the effect of cloud movement on PV system can be monitored. This monitoring technique employs only local measurements of bus voltages and line current to measure the apparent impedance seen at the installation point. The practical application of measured impedance as a monitoring technique shows its effectiveness for distribution system monitoring in presence of various PV PL.

An Impedance-Based Method for Distribution System Monitoring

“…The capability of the impedance based method for reverse power flow detection was shown in [15]. In this paper it will be shown that the apparent impedance has a good potential for monitoring of feeder power factor, in addition to reverse and forward active and reactive power flow.…”

“…To do so, for an impedance measuring unit , located at sending end of Fig.1 (bus 1) the apparent impedance measured by an impedance measuring unit is calculated by [15]:…”

“…Mortazavi et al proposed an impedance based monitoring technique for reverse power flow detection in [15]. It was shown that the apparent impedance is sensitive to small load variation.…”

Sensor-Less Five-Level Packed U-Cell (PUC5) Inverter Operating in Stand-Alone and Grid-Connected Modes

“…Multilevel inverters are designed based on configuration of more switches and DC supplies to achieve the goal of generating various voltage levels at the output. Such inverters generate low harmonic waveforms; therefore they are most suitable for energy conversion applications to deliver efficient power to the loads from renewable energy sources like photovoltaic systems [3][4][5][6].…”

Active Node Detection in A Reconfigurable Microgrid using Minimum Spanning Tree Algorithms

“…Lastly, the selectivity and speed should be in an acceptable level. Communication assisted protection strategies are a common solution to protect the microgrid [5][6][7][8][9]. Common issues like sympathetic tripping, false tripping, blind zone, variation in fault levels and unwanted islanding are caused due to the impact of distributed generations [10].…”