How to solve the fundamental frequency voltage rise after series reactor in low-voltage power capacitors
Dec 31, 2025| After a series reactor is connected to a low-voltage power capacitor, a voltage rise phenomenon occurs at the fundamental frequency. This is mainly due to the resonance between the impedance of the reactor and the capacitance of the capacitor at certain frequencies, leading to an increase in voltage. The methods to address this voltage rise phenomenon include the following:
(1) Adjust the inductance value of the reactor: By adjusting the inductance value of the reactor, the resonant frequency between the reactor and the capacitor can be shifted away from the fundamental frequency of the power grid. Typically, the resonant frequency is set to higher harmonic frequencies (such as the 5th or 7th harmonic) or above.
(2) Add damping resistors: Incorporating appropriate damping resistors in the reactor or capacitor circuit can effectively reduce the resonance peak and mitigate the extent of the voltage rise. However, this will also increase circuit losses.
(3) Optimize the grounding system: A well-designed grounding system can help reduce interference from fundamental frequency voltage. It is essential to ensure good contact in grounding equipment and keep the grounding resistance within a reasonable range, thereby optimizing the dynamic response of the entire power system.
(4) Implement input and output protection devices: Consider adding input and output protection devices in the power system, such as overvoltage protectors, to provide multi-layered protection for the equipment. In the event of abnormal voltage, these protection devices can automatically cut off the circuit, preventing damage to the system and equipment caused by the fundamental frequency voltage rise.
(5) Select appropriate capacitor and reactor combinations: During the design phase, choose capacitor and reactor combinations that match the characteristics of the power grid to ensure that the fundamental frequency and harmonic frequencies do not trigger voltage rise issues.