Selective Monitoring of Power Quality Indicators in Distribution Networks with a Large Share of RES Generation

Abstract

The development of generation based on renewable energy sources (RES) plays an important role in achieving carbon neutrality. Modern solar and wind power plants are connected to distribution electric networks through inverters, which implement power output control and protection algorithms. With a low load of these inverters, violations of the standardized levels of power quality indicators (PQI) are recorded, such as voltage deviations, fluctuations, dips and non-sinusoidality. This is the case with low levels of solar radiation at solar power plants and small wind heads at wind farms. As a rule, the mix of industrial consumers connected to such distribution networks includes electric loads for which deviations of the PQIs from their standardized values are critical and lead to their disconnection by protections, shutdown of technological processes, damage from spoilage, and under-delivery of products. For identifying the disturbance sources and filing lawsuits to compensate for damages, industrial consumers introduce various PQI monitoring systems. A selective monitoring method for automatically detecting violations of the standardized PQI values is considered. To take into account the combined effect of PQIs on electric loads, it is proposed to use the modulus of the current and voltage mutual correlation coefficient. The PQI monitoring device structural diagram is considered, which is based on the results from simulating various network operation modes, as well as the sequential Wald analysis procedure. The introduction of this device will make it possible to prevent significant and long-term violations of the PQIs, thereby ensuring reliable operation of industrial consumers in distribution networks with a large share of RES based generation.