In photovoltaic (PV) energy storage and new energy power generation systems, reactors come in various types, each with distinct structures and characteristics suited to specific applications. Here are the common types and their features:

 Classified by Magnetic Circuit Structure

 Air-core Reactors  

   Structure: Windings are wrapped around hollow frames made of nonmagnetic materials (e.g., epoxy resin, plastic), with no iron core. The magnetic circuit relies primarily on air.  

   Features: Excellent linearity (inductance is minimally affected by current changes), low losses, and superior heat dissipation. Ideal for high-frequency or large current fluctuation scenarios.  

   Applications: Commonly used at the output of PV inverters to suppress high-frequency harmonics, or in energy storage converters to limit rapidly changing inrush currents.

 Iron-core Reactors  

   Structure: Windings are wound around iron cores made of magnetic materials like silicon steel sheets, leveraging the core to enhance magnetic flux and achieve high inductance in a compact volume.  

   Features: High inductance and small size, but prone to magnetic saturation (inductance decreases under large currents), requiring anti-saturation designs.  

   Applications: Suitable for low-frequency, stable current scenarios, such as limiting continuous currents in energy storage battery charging/discharging loops or reactive power compensation circuits on the grid side.

 Classified by Functional Purpose

 Filter Reactors  

   Function: Work with capacitors to form LC filter circuits, eliminating high order harmonics (e.g., 3rd, 5th, 7th harmonics) generated by PV inverters and energy storage converters, thereby reducing harmonic pollution to the grid.  

   Features: Inductance values are tailored to match system harmonic frequencies (e.g., 150Hz, 250Hz).

Series Reactors  

   Function: Connected in series in circuits to limit short-circuit currents or surge currents, protecting equipment like inverters and energy storage batteries from impacts. For example, they suppress inrush currents when PV arrays are connected to inverters.  

   Features: High rated current and short-time current withstand capability.

 Shunt Reactors  

   Function: Connected in parallel in the system to compensate for capacitive reactive power in lines or equipment, stabilizing voltage levels. In high-voltage PV energy storage grid-connected systems, they counteract the distributed capacitance effect of cables to prevent voltage rise.  

   Features: Typically used on high-voltage sides (e.g., 10kV and above) with large capacity.

 Smoothing Reactors  

   Function: Suppress DC current ripples on the DC side (e.g., between PV strings and inverters, or between energy storage batteries and converters), making the current more stable and reducing interference to equipment.  

   Features: Suitable for DC circuits, with inductance values matching the system's ripple frequency.

 Current-limiting Reactors  

   Function: When a short-circuit fault occurs in the system, they limit the amplitude of short-circuit currents through their own inductance, reducing the impact on switchgear，cables, etc.  

   Features: Must withstand short term large currents, with high requirements for mechanical strength and heat resistance.

Other Special Types

 Dry-type Reactors  

   Features: Insulated by air or encapsulated in epoxy resin, oil-free, and with good fire resistance. Suitable for PV power plants, energy storage containers, and other places with high safety requirements.  

   Applications: Widely used in medium and low-voltage PV energy storage systems, replacing traditional oil-immersed reactors.

Saturable Reactors  

   Features: Utilize the saturation characteristics of iron cores to achieve nonlinear adjustment of inductance, enabling dynamic control of reactive power or current.  

   Applications: Used in dynamic reactive power compensation of energy storage systems to stabilize voltage fluctuations.

The selection of reactors in PV energy storage systems depends on specific scenarios (e.g., AC/DC side, high/low frequency, harmonic suppression/current limiting). Common types include air-core reactors, iron-core reactors, filter reactors, and series reactors. Dry-type structures are more suitable for new energy scenarios due to their safety. Different types of reactors work together to ensure system stability, safety, and power quality.