ارزیابی موقعیت برقگیرها برروی شبکه های EHV و UHV

ارزیابی موقعیت برقگیرها برروی شبکه های EHV و UHV

ارزیابی موقعیت برقگیرها برروی شبکه های EHV و UHV

حجم فایل : ۳۷۹KB

تعدادصفحه :۹ صفحه

فرمت فایل :PDF

قیمت فایل:رایگان

در صورت دانلود فایل ترجمه شده این مقاله اینجا کلیک کنید

ارزیابی موقعیت برقگیرها برروی شبکه های EHV و UHV

Probabilistic Evaluation of Optimal Location of Surge Arresters on EHV and UHV Networks Due to Switching and Lightning Surges

Abstract—Switching surges are of primary importance in insulation coordination of extremely high voltage and ultra-high voltage networks. However, in regions of high lightning activity or high ground resistance insulation design, preferably, should be based on the risk of failure caused by lightning and switching surges and the probability of line outage, a combination of lightning and switching flashover rates (SSFOR). This paper describes an effective installation of transmission line arresters (TLAs) to obtain a better protection
scheme (i.e., minimizing global risk to the network). As a consequence, protection costs are reduced in accordance with the costs of elements actually protected and the number of TLAs utilized. In order to accomplish this, a probabilistic method for calculating the lightning related failure and an artificial neural network for estimating the SSFOR are presented. A multicriteria optimization method based on a genetic algorithm is also developed to determine the optimum location of TLAs.

Index Terms

Artificial neural network (ANN), failure-risk analysis, genetic algorithm (GA), overvoltages, transmission-line arresters.

I. INTRODUCTION

THE insulation level of power networks at the planning stage is decided on the basis of the peak value of transient overvoltages. In general, with the increase of operating voltage, switching overvoltages rather than lightning surges determine the insulation level of the network. Then, the insulation level of extremely high voltage (EHV) and ultra-high voltage (UHV) systems is largely determined by the switching overvoltages
(i.e., the probability of switching surge flashover rate (SSFOR)) [1], [2].

However, the SSFOR is normally not considered a standalone criterion. In areas of low lightning activity, the SSFOR may be selected higher than for the areas of high activity, since the probability of lightning faults, which cause the breaker to reclose is high. So there should be a compromise between the SSFOR and the lightning flashover rate (LFOR) of the network. This concept is called the storm outage rate (SOR) and is the
SSFOR multiplied by the LFOR [3]. Nevertheless, in regions of high ground resistance, lightning overvoltages of high magnitude can occur that may lead to insulation failure. Thus, for better protection of EHV networks, lightning-related failure risk can also be considered.

منبع : http://www.elearnica.ir