Power
Ali Morsagh Dezfuli; Mahyar Abasi; Mohammad Esmaeil Hasanzadeh; Mahmood Joorabian
Abstract
The utilization of distributed generation (DG) in today's power systems has led to the emergence of the concept of microgrids, in addition to changing the mode of generating and supplying the energy required for network electrical loads. When a microgrid operates in the island mode, energy generation ...
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The utilization of distributed generation (DG) in today's power systems has led to the emergence of the concept of microgrids, in addition to changing the mode of generating and supplying the energy required for network electrical loads. When a microgrid operates in the island mode, energy generation sources are responsible for controlling the microgrid’s voltage and frequency. As the microgrid frequency is proportional to the amount of power generated by the DG, the microgrid requires a precise power-sharing strategy. Considering that DGs do not usually have stable output power despite the importance of power stability, the present paper addresses the voltage and frequency control of an islanded microgrid by considering the power generation uncertainties caused by disturbances and the varying power output of DGs. Given that the disturbance on the first DG's input current is 0.2 A, which is approximately 2.2% of the steady-state value, a simulation was performed, and it was observed that the maximum voltage variation of each bus in the worst case was 0.59% for the first bus and 0.53% for the second bus, which means that the controller could control the voltage and frequency values within the permissible range. If the controller is not used, the change in the frequency of each bus will be 10 times, and the voltage change will be 5 times as great as that of the case the controller is used.
Power
Mahyar Abasi; Nima Heydarzadeh; Arash Rohani
Abstract
The phenomenon of broken conductor faults (BCFs) in power transmission lines and, consequently, the suspension of the hot-line with no connection to ground, tower, or other conductive/non-conductive bodies is amongst special faults in terms of fault detection and location in the protection industry. ...
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The phenomenon of broken conductor faults (BCFs) in power transmission lines and, consequently, the suspension of the hot-line with no connection to ground, tower, or other conductive/non-conductive bodies is amongst special faults in terms of fault detection and location in the protection industry. Once such a failure occurs, the current of the faulty phase does not increase, which leads to the inability of standard fault detection functions in detecting the event. On the other hand, the variable nature of transmission line parameters due to weather conditions leads to misoperation and malfunction of fault detection and protection schemes of industrial relays in some cases. This paper, for the first time, presents a BCF location scheme without requiring line parameters data and only using magnitudes of current and voltage phasors of a single terminal based on Group Method of Data Handling (GMDH). In this method, a function is interpolated, the inputs of which are the current and voltage of the faulty phase, and its output are the accurate location of the fault. The function can be developed for all topologies of transmission lines. The proposed method is implemented in the MATLAB software and the obtained results verify the solidity and perfect performance of the method for different fault conditions.