Error Analysis Of Low-Voltage Measurement And Protection Device

Low voltage system refers to less than 1200 V voltage systems.There are some apparatuses for low voltage systems,such as power meter,power protection equipment,power controller etc.The apparatuses measure the voltage,current,power,frequency,and other parameters of the power grid.Then do some protection and control.There are many types of low-voltage measurement and protection equipment in the market.There are many proposals about the device.But there are fewer documents to analyze the key parameters of the devices.And there are fewer guides about the low-voltage device design.The paper analyzes many different low-voltage devices and finds the key point of the design.The error of the measurement is the important point according to the device.So the paper analyzes the hardware and software of the device.And finds the main points influence the measure error.And the paper uses different measurement and protection algorithms.Then new designer can use the suitable parts and algorithms according to technical requirements and economic requirements.For the actual product,the most important point is the technical parameter meeting the appropriate standards.This paper analyzes the definitions of the errors,the corresponding product standard error etc.Then analyze the various parts of related products from hardware and software to facilitate the actual product design.According to the theoretical analysis,design multi-function power meters,power calibration equipment,frame circuit breaker controller,and test the products to verify the correctness of the theory.Then improve the design to meet the requirements of the actual product.Multifunction Power Meter uses the proposal of energy chip;improve measurement accuracy by increasing the preamp,oversampling,digital filtering etc.Power calibrate measuring device uses high-precision AD and measure the signal according different segments to fit the requirement.The circuit breaker controller improves measurement and protection accuracy by use high-precision AD,digital integration and half-cycle calculation.The result of the design can meet the standard of the low-voltage devices.