Calculation Of Geomagnetic Induced Current And Its Reactive Power Loss In Power Grid

The gradual maturity of the regional grid interconnection pattern has made the grid structure more complex,Thus,the possibility of disasters caused by geomagnetic induced current caused by geomagnetic storms to power grid is greatly improved.GIC flows into the grid through the neutral ground of the transformer and generates bias flux in transformer windings,which saturates the transformer,leading to system reactive power and harmonics increase and threaten the safe and stable operation of power grid.Therefore,accurate calculation of GIC and reactive power loss in ultra and extra high voltage power grids is of great significance to the evaluation and prevention of geomagnetic storm disasters in power grids.The main work and research results of this paper are as follows:Firstly,this paper introduces the commonly used calculation methods of induced geoelectric field.Considering the actual situation in China,the"large source model" plane wave method is applied to calculate the geoelectric field.The typical strong magnetic storm data is analyzed.Combined with the Gansu power grid area under different earth models,the effects of different geodetic models on the geoelectric field are analyzed in the time domain and the frequency domain respectively.At the same time,the correlation between the magnetic index and the geoelectric field is also studied.Secondly,according to the quasi-DC characteristics of GIC in the power grid,the equivalent model of the components and the processing method of the nodes in the network are explained.The calculation method of GIC in homogeneous land and block earth are expounded.Taking the Gansu power grid as the research object,the GIC of uniform and block earth are calculated.Through comparison and analysis,the results show that it is necessary to consider the block earth for the GIC calculation of power grid.According to the main transformer parameters of Lanzhou East Substation,the GIC limit of 750 kV transformer in Gansu Power Grid is calculated,and the GIC over-limit situation of Gansu Power Grid under transformer in Gansu Power Grid is calculated,and the GIC over-limit situation of Gansu Power Grid under block earth is given.The GIC of each substation in Gansu dual-voltage under the block earth is calculated.Finally,the two calculation methods of GIC-Q are compared,and the consistency of GIC-Q is verified using the existing transformer experimental data.The results show that the GIC-Q difference calculated by the two methods is very small within a certain range of GIC,and the difference gradually increases with the increase of GIC,but it meets the engineering error requirements.Using the GIC-Q's K value algorithm to calculate the GIC-Q of the Gansu power grid.The distribution of GIC-Q in the network in both cases are analyzed.The research methods and conclusions of this paper have a certain guiding role for the prevention and control of GIC in power grid and the reasonable installation of straightening devices.