Research And Development Of Power Quality Monitoring Instrument For Medium And Low Voltage Grid

In recent years, power electronics technology was developed rapidly and a variety of power devices, which rely on power electronics technology, was widely used. On the one hand, the emergence of power electronic devices improved the efficiency of industrial production, which makes a greater contribution to raising the level of the national economy; On the other hand, the environment of public power was deteriorated as a result of widely using power electronic devices, power quality is also declining. Therefore, the power quality monitoring of power supply system will be an important field of power system research. Real-time measurement of public power and the basic power parameters of nonlinear electrical equipment (such as voltage, current, frequency, power, power factor, etc.) is certainly necessary, and measuring the harmonic components of the system is more important to grasp the actual situation of system harmonics. So it is essential that we should prevent from harmonics and improve power.With the constant improvement of DSP technology and mature manufacturing technology of DSP chips, the special hardware structure and software structure makes DSP chips have more advantages of calculating speed and accuracy than traditional microprocessors ; High-density integration and the rich resources of External devices cut down price and cost of the chips, which make they have greater advantages than the industrial computer systems. With the extensive application of DSP technology, advanced software algorithms are also emerging, such as FFT algorithm, by sine signal method, instantaneous reactive power method, wavelet transform method, which are used for harmonic analysis. Therefore, the DSP technology has certain competitiveness the field of monitoring and control of power system.Considering design requirements of the device, TI's TMS320F2812 will be used as core processor to the power quality monitoring and control equipment, which is applied to intermediate and low voltage power system. It will have both acquisition data function and control function, which can measure and calculate the basic single-phase AC power circuit parameters .The cumulative electric reactive energy, fault recording, detection of 2-15 harmonics and the corresponding power spectrum graphics functions are also included; Additionally, 16 SOE events will be recorded, which is finished by detecting the states of 4-way input switches. Four buttons can set or modify the external circuit wiring, 2 relay output states, cumulative value and the real-time clock, can also check SOE events and relay output status. In this way, the instrument can achieve human-computer interaction.