Six standards for digital power quality monitoring devices

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This post was last edited by chenjinfeng on 2020-3-1 at 16:37. With the rapid development of the power industry, in the field of power consumption, on the one hand, the widespread application and advancement of power electronics technology have led to the addition of numerous nonlinear loads in power supply systems, such as static converters and industrial AC/DC conversion devices. These loads cause distortions in the current and voltage waveforms of the power grid, resulting in harmonic \"pollution\" of the grid. Impactful and fluctuating loads, such as electric arc furnaces, large-scale rolling mills, and electric locomotives, not only generate a large amount of high-order harmonics during operation, but also cause increasing voltage fluctuations, flicker, and three-phase imbalance. These adverse effects on the power grid not only reduce the safety of the power supply and consumption equipment itself, but also severely disrupt the efficient operation of the grid, causing \"pollution\" in the grid. On the other hand, places such as airports, banks, manufacturers of precision electronic components, computer networks, and service monitoring centers have high requirements regarding power quality; advanced technologies and equipment increasingly demand high-quality electricity. To this end, the **Technical Supervision Bureau has successively issued standards covering six aspects of power quality**:  Power Quality – Harmonics in Public Power Grids GB/T14549-1993 ；  Power quality: Voltage fluctuations and flicker GB12326-2000 ；  Power quality: Allowable voltage unbalance for three-phase systems GB/T15543-1995 ；  Power quality: Allowable deviation of supply voltage GB/T12325-2003 ；  Power quality: Allowable frequency deviation in power systems GB/T15945-1995 ；  Temporary overvoltages and transient overvoltages: GB/T18481-2001. The Notice issued by the Ministry of Electric Power regarding the promulgation of the “Regulations on the Technical Supervision and Management of Power Quality in Power Grids” states that: “The power quality of grid-supplied electricity is an important indicator of products in the electric power industry; it relates to the interests of investors and operators involved in power generation, supply, and consumption. Good power quality is crucial for ensuring the safe and efficient operation of electrical equipment and various appliances in power grids and among end-users, for maintaining normal production processes and product quality across all sectors of the national economy, and for improving the quality of life for people.” At the same time, some power quality indicators are greatly affected by certain electrical loads. Ensuring power quality comprehensively is a shared responsibility and obligation of power companies and users. **Appropriate requirements have been stipulated in the Electricity Law; therefore, power grid operators at all levels must pay attention to continuously improving the quality of electric power, and earnestly implement these regulations in light of the actual conditions of their respective grids. ”Digital power quality monitoring devices are primarily used to monitor, analyze, and evaluate the power quality at specific monitoring points. They mainly offer five key functions: real-time power quality monitoring, power quality event alerts, waveform recording, data statistics, and evaluation analysis. The main indicators for real-time monitoring and analysis include: basic electrical parameters, voltage deviation, harmonic voltages, harmonic currents, interharmonics, frequency deviation, three-phase voltage unbalance, voltage fluctuations, and flicker. All parameters monitored in real time as well as power quality indicators can be stored and retrieved over a long period of time. It provides event alarms and waveform recording analysis functions for power quality violations, voltage sags, and voltage swells. Digital power quality monitoring devices are suitable for monitoring power quality on the user side or on the generation side, meeting various monitoring requirements such as those for wind farms, distribution networks, and transmission voltage hubs.