Research On Characteristics Of Rogowski Coil Current Transformer And Its Influence On Protection

The dependence of modern society on power supply determines the unshakable position of the power system in Chinese economic system,so guaranteeing the reliable operation of the power system is an eternal topic.At the same time,for the issues like climate change,resource consumption,energy security,and sustainable supply,scholars around the world are working hard to develop green energy and improve energy efficiency.Under the circumstances,in order to make the communication of the power grid and users diverse and friendly,it is a general trend to build a strong smart grid with the three technical characteristics of "informatization,automation,and interaction".At present,China is in the third stage of building a smart grid so that there is an increasing demand for smart high-voltage equipment.Because the electronic transformer is a very critical part of it,so the research of it is very necessary.Because of its excellent performance,electronic current transformers based on Rogowski coils are widely used in the protection,measurement and control of smart substations.However,in the actual application process,the Rogowski coil current transformer causes the malfunction of the over-protection due to its related characteristics,so in order to guarantee the power grid’s safe operation,it needs to be ameliorated.So This article has made a detailed analysis of the transmission characteristics and dynamic response characteristics of the Rogowski coil electronic current transformer.Firstly,this paper builds the centralized parameter and distributed parameter models of the Rogowski coil sensor head,and analyses the applicable frequency of the two models quantitatively.According to the IEC standard for electronic transformers,this paper pointes out the error and advantages of adopting the centralized parameter model.Then,according to the measured Rogowski coil parameters,this paper pointes out the frequency characteristics of the Rogowski coil sensor head parameters,and the Rogowski coil which is closest to the theoretical value of the centralized parameter model is selected as the parameter basis for the analysis of the transmission characteristics.And then,through the amplitude-frequency and phase-frequency analysis of the sensor head,the integration circuit and the filter circuit,the improvement measures to improve the transmission accuracy of the Rogowski coil current transformer are obtained,and the effectiveness of the measures is verified by simulation.Then,this article uses the Rogowski coil current transformer produced by the actual manufacturer to conduct a dynamic test and find that the dynamic response problem is widespread.Subsequently,this paper analyses the reason that the Rogowski coil current transformer generates the dynamic additional component,and combined with the principle of the differential protection algorithm,the cause of the protection misoperation by the dynamic additional component is pointed out.Finally,this paper uses PSCAD to build a power grid simulation model to analyse the factors that affect the value of the dynamic additional component,and proposes measures to suppress the dynamic additional component to reduce the risk of protection misoperation from the perspective of improving the sampling link and filtering link.And through the error analysis of the fundamental component and the output results before and after the improvement,the feasibility and effectiveness of the measures are verified.