The Research On Methods And Uncertainty Of Measuring Electric Quantity About Intelligent Release

Intelligent release is intelligent circuit-breaker's core part. It can protect all kinds of faults about ordinary circuit-breaker. It can show all kinds of electric quantities about main load circuit. Measurement and show function is a main function of intelligent release. Measurement methods of electric quantity are introduced about intelligent release first. Major electric quantities are RMS current, RMS volate and active power.Three-phase current detection is base that intelligent release detects faults and carrys out three-section protection. When main circuit is normal the measurement methods and mathematical models of measurement are different from short-circuit. Principal analysis is about major uncertainty source when normal. The mathematical models of measurement and errors models are presented. The measurement method and mathematical models of measurement affect uncertainty of measuring electric quantity. The methods to decrease uncertainty of measurement are presented.In measuring RMS volate and RMS current the complex Simpson integral method is used to reduce uncertainty of measurement. Short-circuit current is about short-circuit course and definition of short-circuit current. Accuracy of measuring short-circuit current is about accuracy of transformer and the mathematical models of measurement. Measuring short-circuit current proposes protection. Adjusting current value can offset effect of uncertainty. When main circuit is short-circuit, the uncertainty of measurement is greater than when. normal,need not have high accuracy,technique allow. The movement method to clear up unusual value and void value is introduced.Using scientific measurement methods, using new-type high accuracy transformer, using high rate microprocessor and high reliability parts, getting correct mathematical models, getting overall analysis methods of uncertainty source, using the hardware and software methods to decrease uncertainty of measurement, measuring RMS current, RMS volate and active power have high accuracy. The basic principles of the design are accounted detail,the selective bases and the operational principle of the hardware are introduced chiefly and the design reasons and program means of the software are recommend in this thesis.