Differences in Power Quality Between High and Low Voltage Systems

Power quality is a core element for the safe and economical operation of a power system. Due to differences in voltage levels and application scenarios, there are significant differences in power quality issues, impact levels, and mitigation strategies between the low-voltage (1kV and below) and high-voltage (above 1kV) stages. Specifically:

As the final distribution link in the power system, the low-voltage side covers residential, commercial, and industrial terminals. Due to the high proportion of nonlinear loads (inverters, household appliances) and single-phase loads, it is prone to voltage deviations, large 3rd/5th/7th harmonics, low power factor, and three-phase imbalance. The impact is limited to local distribution systems, manifesting as equipment heat loss, malfunction of precision instruments, and increased energy consumption. Mitigation requires equipment such as low-voltage capacitor banks and APF/SVG, which offer flexible installation and controllable costs.

The high-voltage side bears the core responsibilities of power grid transmission, renewable energy grid connection, and large-scale industrial high-voltage power supply. Affected by grid faults, large equipment switching, and lightning strikes, it frequently experiences voltage dips/surges, complex harmonics/interharmonics, reactive power surges, and transient overvoltages. These problems have a grid-wide impact, potentially leading to substation tripping, large production line shutdowns, or even regional power outages. Mitigation requires the use of large-capacity equipment such as high-voltage capacitor banks, high-voltage SVG/SVC, and surge arresters, and must be coordinated with local grid protection mechanisms, resulting in high technical complexity and investment costs.

Identifying the characteristics of power quality at different voltage levels and developing scientific mitigation solutions is crucial for the efficiency and safety of the power system!