What Is the Role of High-Voltage Reactors in Substations?
Nov 13, 2025| In the power system, substations are not only responsible for the transmission and distribution of electrical energy but also play a crucial role in ensuring power quality and the stable operation of the grid.
I. What Is a High-Voltage Reactor?
A high-voltage reactor is a passive electrical device primarily characterized by its inductance. It typically consists of an iron core, windings, insulation structure, and a cooling system. Its main feature is a large inductance value. When current passes through it, an induced voltage is generated across the reactor, thereby limiting the rate of current change or suppressing harmonic currents.
II. Key Functions of High-Voltage Reactors in Substations
1. Preventing Excessive Short-Circuit Currents
During grid operation, if a short-circuit fault occurs, the current can surge instantaneously, potentially causing switchgear burnout, busbar deformation, or even system collapse. In such scenarios, high-voltage reactors act as "current limiters." By leveraging their inductive impedance, they restrict the rise of short-circuit currents and prolong the current rise time, buying critical response time for protection devices (such as circuit breakers and relay protection systems). This effectively prevents equipment damage and mitigates the escalation of faults.
2. Improving Power Factor
Substations often employ shunt capacitor banks to compensate for reactive power and improve the power factor. However, these capacitors can resonate with system harmonics, leading to equipment damage or voltage distortion. By connecting high-voltage reactors in series with the capacitor banks, harmonic currents from the grid can be effectively suppressed, preventing capacitor overcurrent.
3. Stabilizing System Voltage
In grids with long transmission lines or significant load fluctuations, voltage often experiences rises or dips, adversely affecting equipment operation. Shunt reactors can absorb excess reactive power in the system, preventing voltage spikes during light-load conditions.
4. Suppressing Harmonic Interference
Modern power systems contain numerous nonlinear devices (such as frequency converters, arc furnaces, and rectifiers), which tend to generate harmonic currents and degrade power quality.
Filter reactors installed in substations, combined with filter capacitors, form filter circuits that effectively absorb specific orders of harmonic currents. This prevents harmonics from propagating through the system, thereby protecting transformers, switches, and other equipment from harmonic damage.