State Grid Xuzhou Power Supply Company: Pilot application of end-point 'voltage regulators'

State Grid Xuzhou Power Supply Company recently installed a new type of voltage regulator – a low-voltage distributed reactive power compensation device – at the Longchi Chenzhuang South Transformer Area of the 10 kilovolt Dunchi Line in Pizhou, Xuzhou, Jiangsu province. This device can monitor line voltage in real-time. Once abnormal voltage at the end of the line is detected, it instantly performs automatic compensation, steadily controlling the voltage within the qualified range.

In recent years, the energy structure transformation in the Xuzhou area has accelerated, bringing new challenges to power grid operation. On one hand, the large-scale integration of distributed photovoltaic systems leads to reverse power flow of surplus electricity during peak generation periods, easily causing voltage rise at the end of the line. On the other hand, the widespread use of high-power equipment such as air conditioners and industrial motors creates significant inrush currents during startup, resulting in instantaneous voltage drops. This has transformed the traditional unidirectional "low voltage" issue into a bidirectional voltage fluctuation problem that requires both preventing lows and controlling highs.

To address this, State Grid Xuzhou Power Supply Company has innovatively adopted a refined "two-pronged" governance strategy: During daytime periods of high photovoltaic output when voltage is prone to exceeding limits, transformer output is precisely adjusted to appropriately lower the supply voltage at the source, thereby freeing up space for photovoltaic power and effectively preventing excessive voltage at the line end. During periods of low end-point voltage, the low-voltage distributed reactive power compensation device is used to quickly and precisely boost voltage, ensuring stable voltage at the end.

Boosting voltage at the source often fails to stabilize voltage at the line's end, while end-point boosting is costly and prone to instability. To address this, State Grid Xuzhou Power Supply Company uses data analysis to ensure the compensation devices are installed at the "golden points" along the line. This approach prevents the issues of source boosting not reaching the end and costly, unstable end boosting, thereby stabilizing the entire line voltage most effectively at the lowest cost.

State Grid Xuzhou Power Supply Company has piloted the installation of 113 low voltage distributed reactive power compensation devices in areas like Xinyi and Pizhou. Estimates indicate that after the devices were put into operation, the weekly voltage limit violation duration in the transformer areas was reduced by approximately 3,000 hours, the customer voltage qualification rate increased by over 30 percent, and the average end-point voltage increased by 5 to 10 volts, demonstrating significant effectiveness in voltage management.