Research And Design Of High Precision Voltage Monitor Verification Device Based On FPGA

Voltage monitor is an electronic device which can continuously monitor the slow changes of the normal operation status of the power system caused by voltage deviation. As an important tool for monitoring the voltage quality, the reliability and accuracy play an important role in ensuring safety of electricity supply and the accuracy of electric energy measurement. However, because of the long-term use of the voltage monitor, the accuracy of voltage monitor measurement could be led to reduce by the aging of devices, parameter drift, environmental impact and other factors, so it needs to be periodically verified. This thesis is to solve the problem above through designing a voltage monitor verification device which can ensure voltage monitor verified timely and accurately based on FPGA (Field Programmable Gate Array) and the direct digital synthesis (Direct Digital Synthesis, DDS) technology.Firstly, the subject background and research status at home and abroad are introduced in this thesis, also the technical specifications of the voltage monitor device are presented. Secondly, the function and working process of the device are described, and the overall structure design of the system is stated at the same time. Thirdly, the working principle of direct digital frequency synthesis (DDS) is discussed. The binary data of wave amplitude which has a certain interval of the phase is stored in the high-speed memory as lookup table for frequency synthesis to make output phase continuous and improve the frequency resolution by considering the concept of phase. Fourthly, the design schemes of the FPGA peripheral circuit, the digital to analog conversion circuit, the filter circuit and the power amplification circuit are described in detail, and also simulation experiments are made by the software of Multisim to show that the design scheme of voltage monitoring device is feasible.Finally, the experiment is made in the test prototype. The result shows that the verification device can not only produce grade 0.05 standard voltage source also dynamically display the signal frequency and instantaneous value of sinusoidal signal voltage. The frequency, phase and amplitude of the device are adjustable, and the technical specifications such as precision and noise immunity reach the expected goal basically.