Calculation method of thermal stability safety margin for overloaded transmission lines considering power variation
With the increasing complexity of power grid interconnection,thermal stability has become the main fac-tor limiting power transmission capacity.Especially in the case of transmission lines passing through loads,the ex-isting methods ignore the dynamic thermal characteristics caused by line power changes,resulting in errors in the calculation of line thermal stability safety margin,which may lead to premature protection action and line removal,or even threaten the safe and stable operation of the entire power system.Therefore,the factors affecting the tem-perature rise of transmission lines are analyzed,and the sensitivity model between unit operation mode,power regu-lation and overload line power is established.Combined with the dynamic thermal balance equation of the line,a method for calculating the thermal stability safety margin of overload lines considering the power change is pro-posed.The numerical example in this paper shows that the method fully considers the influence of power variation of overloaded line on thermal stability,and can maximize the delay of protection action while ensuring the safe oper-ation of transmission line,so as to reduce the scope of outage and chain fault.
thermal stabilitydynamic thermal characteristicsallowed over load timemargin of safetyload power regulation
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