What is PCS Energy Storage Converter?

PCS (Power Conversion System) energy storage converter is a bidirectional controllable current conversion device that connects the energy storage battery system and the power grid/load.

The core function of PCS is to control the charging and discharging process of the energy storage battery, convert AC and DC, and directly supply power to the AC load in the absence of a power grid.

The working principle of the energy storage converter is a four-quadrant operation converter device that can be controlled on the AC and DC sides, which realizes the AC and DC bidirectional conversion of electric energy. The principle is to control the constant power or constant current through the microgrid monitoring instructions, charge or discharge the battery, and smooth the output of fluctuating power sources such as wind power and solar energy.

The PCS energy storage converter can not only convert the direct current output of the battery system into alternating current that can be transmitted to the grid and other loads, but also complete the discharge; At the same time, the alternating current of the power grid can be rectified into direct current to charge the battery.

The energy storage converter (PCS) is composed of software and hardware appliances such as power, control, protection, and monitoring. Power electronics are the core components of energy storage converters, which mainly realize the conversion and control of electrical energy. Common power electronics include thyristors (SCRs), thyristors (BTRs), relays, IGBTs, MOSFETs, etc. These devices enable the flow and conversion of electrical energy by controlling the switching state of current and voltage.

Control circuits are used to achieve precise control of power electronics. The control circuit generally includes modules such as signal acquisition, signal processing, and control algorithms. The signal acquisition module is used to collect input and output current, voltage, temperature and other signals, and the signal processing module processes and filters the collected signals to obtain accurate parameters; The control algorithm module calculates the control signal according to the input signal and the set value, and is used to control the switching state of the power electronic device.

Electrical connection components are used to connect energy elements and external systems. Common electrical connection components include cables, plugs and sockets, terminal blocks, etc. The electrical connection parts should have good conductivity and reliable contact performance to ensure the effective transmission of electrical energy, safe and reliable.

The working mode of the energy storage converter PCS is divided into three modes: grid-connected mode, off-grid mode and hybrid mode.

The grid-connected mode of the energy storage converter PCS is to realize the two-way energy conversion between the battery pack and the power grid. It has the characteristics of grid-tied inverters, such as anti-islanding, automatic tracking of grid voltage phase and frequency, low voltage ride-through and so on.

According to the requirements of power grid dispatching or local control, PCS converts the AC power of the power grid into DC power during the load trough period of the power grid, and charges the battery pack, which has the function of battery charging and discharging management; During the peak load period of the power grid, it converts the direct current of the battery pack into alternating current and feeds it back to the public grid. When the power quality is not good, feed or absorb active power to the power grid, provide reactive power compensation, etc.

Off-grid mode, also known as isolated grid operation, means that the energy conversion system (PCS) can be disconnected from the main power grid according to actual needs and meet the set requirements, so as to provide AC power to meet the power quality requirements of the grid for part of the local load.

Hybrid mode refers to the ability of the energy storage system to switch between on-grid and off-grid mode. The energy storage system is in the microgrid, the microgrid is connected to the public grid, and it operates as a grid-connected system under normal working conditions. Common applications include filtering, stabilizing power grids, and regulating power quality.