Three-in-one real-time load curve construction method for railway power supply system

The invention relates to a three-in-one real-time load curve construction method for a railway power supply system. Measuring values of voltage and current are transmitted in a WYZ series remote intelligent terminal device based on time resolution of 5 to 20 ms, so that a load curve spanning a plurality of days is formed in a center master station or a local monitoring system, the change conditions of the voltage and the current are mastered conveniently and accurately, and power supply accidents spanning units or spanning stations and institutions are analyzed by the measuring value time scale which is accurate to millisecond. Three modes of mutation detection, threshold spanning transmission and circulating transmission are adopted during sampling, transmission and storage of the measuring values, so the failure process can be caught completely and the transmission data quantity and the storage data quantity of the measuring values are greatly compressed. Under the coordination of digital filtering, the sta