The Function of Series Reactors in Reactive Power Compensation Capacitors

Connecting a series reactor in series with a reactive power compensation capacitor is a common configuration in power systems. This combination not only enhances system stability but also effectively protects the capacitors themselves and mitigates harmonic interference in the grid.

●The primary purpose of a series reactor is to limit the inrush current during capacitor switching. When a capacitor bank is energized, a significant surge current can be generated. Adding a series reactor effectively suppresses this transient inrush, preventing damage to switching devices. This protective mechanism significantly extends the operational life of the capacitors and improves the safety of system operations.

●A key function of the series reactor is to suppress the amplification of grid harmonics. Harmonics present in the power system can interact with the capacitor bank, forming a resonant circuit that amplifies harmonic currents manifold. Connecting a reactor with an appropriate reactance ratio shifts the resonant frequency, preventing it from coinciding with system harmonic frequencies, thereby protecting the capacitors and the entire grid.

●Another important function of the series reactor is to adjust the compensation characteristics. By selecting reactors with different reactance ratios, the compensation effect of the capacitor bank can be tailored to function correctly even in specific harmonic environments. This flexibility allows the reactive power compensation device to adapt to various complex grid conditions, enhancing system adaptability.

●Improving system stability is also a crucial purpose of the series reactor. In the event of a short-circuit fault, the reactor helps limit the fault current, reducing the stress on the capacitors. It also mitigates the impact of switching overvoltages on the capacitors, ensuring the stable operation of the reactive power compensation system under various operating conditions.

●In modern smart grids, the selection of series reactors has become more refined. Engineers calculate the optimal reactance ratio based on the specific harmonic content and environmental conditions. Typically, a reactance ratio of 5%-7% is used to suppress harmonics of the 5th order and above, while a ratio of 12%-13% is designed for systems with significant 3rd harmonic content, enabling targeted protection.