PCS (Power Conversion System), also known as the energy storage converter, is the core equipment of an electrochemical energy storage system. It is responsible for the bidirectional conversion between alternating current (AC) and direct current (DC), and controls the charging and discharging process of batteries.
Grid-forming PCS is an "advanced version". Unlike conventional converters that only "follow" the grid, grid-forming PCS can actively construct voltage and frequency during grid faults or in weak grid conditions, providing stable support for the power grid.
Core Functions of Grid-forming PCS
Virtual Synchronous Generator (VSG) Technology
The core of grid-forming PCS lies in the virtual synchronous generator algorithm. By simulating the physical characteristics of traditional synchronous generators (such as rotor inertia and damping coefficient) through mathematical models, the PCS is equipped with inertia response and frequency regulation capabilities.
When grid fluctuations occur, grid-forming PCS can release or absorb power within milliseconds to quickly balance power supply and demand and prevent frequency collapse.
Dual-mode Operation
- Grid-tied mode: Under normal grid operation, grid-forming PCS acts as a "slave unit", following the grid voltage and frequency, and providing active/reactive power regulation services.
- Off-grid / island mode: When the grid fails or in remote areas, grid-forming PCS can independently establish voltage and frequency to supply power to local loads, and supports black-start capability (restarting the system without grid support).
Strong Overload Capacity and Anti-disturbance Performance
Grid-forming PCS typically has a short-time overload capacity of 3 times the rated current (e.g., lasting 10 seconds), which can cope with short circuits or impact loads under extreme conditions.
In addition, it can accurately identify grid impedance and operate stably in weak grids to avoid the risk of off-grid operation.