Near Real Time System Short-Circuit Current Online Monitoring Platform and Its Application

With the economic development, the rapid increase of system capacity has led to an increasing level of system short-circuit current, which has brought new challenges to equipment selection and maintenance. Especially for old equipment such as main transformers, due to insufficient capacity to withstand short-circuit, serious accidents such as explosions may be caused, which threatens the safety of power system operation. Therefore, it is necessary to dynamically evaluate the system short-circuit current in the context of the continuous expansion of the grid scale, to ensure that the external environment meets the equipment operation requirements. Traditional short-circuit current calculation adopts offline calculation method, which is obtained by means of numerical calculation by building and simplifying the model of the system architecture. Due to the huge amount of simulation calculation, there is an error in the equivalence, on the one hand, the calculation period is too long and the update is not timely, At present, it is usually calculated once a year, and it is difficult to reflect the actual short-circuit current situation at the location of the grid equipment. In this paper, combined with the frequent switching of reactive power equipment operations in the power grid, the short-circuit current is monitored by comparing the voltage changes before and after reactive power switching, regardless of the specific power grid structure, and the system as a whole is observed for its external characteristics. This avoids complex network calculations and greatly improves the accuracy and timeliness of system short-circuit capacity observation. Since the short-circuit current monitoring platform does not need to change the high-voltage system wiring or install a separate monitoring device, it only needs to obtain and analyze information such as voltage, reactive equipment capacity, and operating years from the existing dispatching platform and ledger system of the power system. Therefore, it has the characteristics of low investment and high safety, and continuous observation can be carried out to obtain the change law of the system short-circuit current level with seasons and loads, which provides a more reliable basis for the evaluation of the operating status of related equipment.. (Abstract)