Abstract
There are several threats that require the control of the conditions of switching operations in the transmission grid. They result mainly from the negative effects of the high-value current, which may appear after the breaker is closed. Problems considering closing the power circuit breakers on a large standing phase angle (SPA) are often formulated by grid operators. The literature most often discusses the problem of SPA reduction, which allows the system to be restored without the risk of damaging the turbogenerator shafts. This reduction can be achieved by various operational solutions; most often, it is the appropriate adjustment of active power generation, sometimes backed up by partial load shedding. The subject of the presented article is a slightly different approach to the SPA problem. The method of determining the maximum value of SPA for which the connection operation allows to avoid excessive transitional torques was presented. With this approach, finding the maximum value of SPA between the two considered system nodes is treated as an optimisation task. In order to solve it, the original heuristic optimisation method described in the article was applied.
Highlights
Switching-on operations in the transmission grid create a number of risks resulting mainly from the emergence of high current values
It should be emphasised that the main objective of the discussed method is to determine the maximum standing phase angle (SPA), which, in a given point of the network and in a given configuration, will ensure the possibility of safe performance of the switching operation from the point of view of the power surge criterion on shafts of generating units
The second stage is the determination of the maximum value of SPA, safe from the point of view of power surges on shafts of generating units Figures 6c,d–10c,d)
Summary
Switching-on operations in the transmission grid create a number of risks resulting mainly from the emergence of high current values. This article considers the problem of fatigue of shafts of generating units due to torsional oscillations caused by the switching of a transmission line with a significant difference of voltage phasors between connecting nodes [1,2]. A relatively easy task is to calculate power surges for the known operating state of the transmission grid, i.e., the actual value of the switch-on angle [3]. An attempt was made to solve this problem by using an original method of heuristic optimisation. The second chapter presents a literature review on the problem of reduction in the SPA of transmission lines.
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