ABSTRACT
In this paper, the optimal utilization of local biogas production in multi-energy systems is investigated. The micro-grid policy of local biogas production, to supply the variable demand of natural gas and also to convert it into electrical energy required by an energy hub micro-grid, along with other sources of scattered energy production and national electricity and gas networks, is one of the main goals of this paper. The multi-factor intelligent optimization method is considered to investigate the non-linear and heterogeneous optimization problem in the IEEE standard 33-bus energy hub microgrid. Most of the main indicators of interest are economic savings and minimization of operating costs. The multi-objective optimization method has been chosen as a method to solve the aforementioned non-linear and heterogeneous problem. Simulation has been done in GAMS software and the results of optimal load distribution of electric energy and natural gas supply for selected energy microhub have been explained and compared. The final results show a significant reduction of 46 % (2.8 thousand dollars per day) in operating costs. Significant reduction of energy flow between local network microhubs by 39.4 % is also one of the optimization results studied. Also, the Island performance of the local energy microhub has been simulated with the desired strategy. The cost of local energy microhub energy supply in island mode has decreased by 34 % (1.4 thousand dollars per day) compared to normal mode. © 2022 Published by.
ABSTRACT
In this work, we present a novel technique to locate partial discharge (PD) sources based on the concept of time reversal. The localization of the PD sources is of interest for numerous applications, including the monitoring of power transformers, Gas Insulated Substations, electric motors, super capacitors, or any other device or system that can suffer from PDs. To the best of the authors' knowledge, this is the first time that the concept of time reversal is applied to localize PD sources. Partial discharges emit both electromagnetic and acoustic waves. The proposed method can be used to localize PD sources using either electromagnetic or acoustic waves. As a proof of concept, we present only the results for the electromagnetic case. The proposed method consists of three general steps: (1) recording of the waves from the PD source(s) via proper sensor(s), (2) the time-reversal and back-propagation of the recorded signal(s) into the medium using numerical simulations, and (3) the localization of focal spots. We demonstrate that, unlike the conventional techniques based on the time difference of arrival, the proposed time reversal method can accurately localize PD sources using only one sensor. As a result, the proposed method is much more cost effective compared to existing techniques. The performance of the proposed method is tested considering practical scenarios in which none of the former developed methods can provide reasonable results. Moreover, the proposed method has the unique advantage of being able to locate multiple simultaneous PD sources and doing so with a single sensor. The efficiency of the method against the variation in the polarization of the PDs, their length, and against environmental noise is also investigated. Finally, the validity of the proposed procedure is tested against experimental observations.
ABSTRACT
This paper presented a new sensor to detect and localize partial discharge (PD) in power transformers based on a fiber Bragg grating (FBG). The fundamental characteristics of the proposed sensor, as a PD detector, were temperature compensation and direction independence. The proposed high-resolution PD detector operated based on the FBG wavelength shift. It is necessary to evaluate the physical parameters of the sensor to achieve the best results. Therefore, in this paper, the detected signal strength was investigated for different angles and temperatures. A Teflon hollow mandrel and two FBGs attached to the inner and outer surfaces of the hollow mandrel were chosen as the inner transformer PD detector. The changes in the sensor output were less than 0.4 mV and 0.5 mV for direction variations and a temperature variation of 14 °C (degrees Celsius), respectively. Consequently, the proposed sensor could be successfully employed for the detection of a transformer PD signal.
