A power conversion system (PCS) is a crucial unit for power exchange between energy storage batteries and the power grid, accounting for approximately 20% of the value of an energy storage system. In recent years, the global energy storage market has experienced explosive growth, increasing the demand for PCS. Domestic manufacturers are continuously expanding into overseas markets, making PCS research a hot topic.
PCS Working Principle and Functions
PCS consists of hardware such as IGBT (Insulated Gate Bipolar Transistor), PCB (Printed Circuit Board), wires and cables, and can be divided into single-camera and triple-camera systems.
PCS (Power Control System) can be categorized into three types based on power output: high-frequency isolation, power frequency isolation, and no isolation. Single-phase and three-phase PCS below 20kW use high-frequency isolation, those from 50kW to 250kW use power frequency isolation, and those above 500kW use no isolation.
The main technical parameters for PCS (Power Storage System) are system voltage, power factor, switching time, and peak power, as these parameters have a significant impact on the function of the energy storage system.
The PCS operates in two main modes: grid-connected and off-grid.
In grid-connected mode, the PCS enables bidirectional energy conversion between the energy storage battery and the grid. Its main function is to perform constant power or constant current control according to microgrid monitoring instructions, to charge or discharge the battery, and to smooth out the highly volatile output of wind and solar power.
In off-grid mode, the PCS can provide local loads with AC power that meets the power quality requirements of the grid, based on actual needs.
The main functions of PCS include protection against over-voltage, under-voltage, overload, overcurrent, short circuit, and over-temperature; islanding detection capability for mode switching; communication with the upper-level control system and energy exchanger; and smooth grid-to-off-grid switching control.
The main features of PCS include an integrated charging and discharging design, enabling bidirectional energy flow between AC and DC systems; seamless switching between grid-connected and off-grid operation; and an arbitrarily adjustable power factor, allowing full reactive power generation within the capacity range for reactive power compensation.
In addition, features include the ability for multiple PCS units to operate in parallel with a total output power of not less than 95% of the total superimposed power; independent operation between individual 10kW converter units; high-reliability power modules used in the main power circuit; support for various energy storage batteries, with only differences in controller software between different models; and comprehensive extreme protection functions to effectively prevent abnormal damage to the inverter.
Application scenarios and domestic manufacturers
Depending on the application scenario, PCS can be divided into four categories: energy storage power station, centralized, industrial and commercial, and residential. The main difference is the power output.
The power of a power storage power station PCS is generally greater than 10MW. It adopts a cascaded multilevel topology and uses IGBT module design. Typically, N AC units are installed inside the container to support parallel operation of multiple units. A transformer is required to step up the voltage and connect to the power grid.
Centralized PCS has a power of over 250KW and currently mostly adopts a two-level topology. It also uses IGBT modular design, uses fewer power devices, and the power of a single unit can reach the MW level, which requires high system reliability.
Industrial and commercial PCS typically have a power output below 250KW. Currently, they mostly adopt a three-level topology and are combined with distributed photovoltaics to achieve self-generation and self-consumption. In foreign countries, they can also profit from the peak-valley price difference of the power grid.
Household PCS with a power output of less than 10KW, combined with household photovoltaic systems, serves as an emergency power source and for electricity bill management, and has high requirements for safety standards and noise levels.
PCS technology is largely equivalent to that of traditional photovoltaic inverters, so the companies that entered the PCS market early on were mostly inverter manufacturers.
From the perspective of the PCS industry chain, the upstream consists of IGBTs, PCBs, etc., the midstream consists of various types of energy storage converters, and the downstream consists of wind and solar power plants, power grid systems, etc.
The core of PCS upstream materials is IGBT. However, IGBT has high requirements for design and process. Chinese companies started late, and currently, foreign multinational companies such as Infineon, Mitsubishi Electric, and Fuji Electric dominate the market. Infineon has the highest market share at 15.9%. However, in recent years, my country's IGBT self-sufficiency rate has been gradually increasing, and domestic products are showing a trend of replacing overseas products.
The midstream and downstream manufacturers of PCS (Polymer Processing System) are basically the same group as photovoltaic inverter manufacturers. Major domestic companies include Sungrow Power, BYD, Kehua Data, Sungrow Power Supply, GoodWe, Kunlan New Energy, Shenghong Power, Soying Electric, and Kelun Electronics. However, due to the inherent barriers to entry in different PCS technologies and their varying application areas, there is currently no absolute industry leader.
Sungrow Power: Primarily focuses on large-scale power-side energy storage PCS products, mainly for supporting its own energy storage systems, with some sales to external parties. Sungrow Power's energy storage business is positioned to provide energy storage system solutions.
Sungrow Power Supply Co., Ltd.: The company's main products are AC energy storage converters and DC energy storage converters, which are respectively applied in the fields of new energy grid connection and joint frequency regulation of thermal power energy storage on the power generation side, frequency regulation and peak shaving on the grid side, and energy storage in the industrial and commercial fields on the user side.
GoodWe offers a comprehensive range of energy storage products and energy solutions, covering a full range of inverters and energy storage batteries, including single-phase, three-phase, high-voltage, low-voltage, DC-coupled, and AC-coupled models.
KSTAR: The company's existing products include modular energy storage converters and centralized energy storage converters, with energy storage business accounting for 10% of total revenue.
Shenghong Technology: Shenghong Technology pioneered the multi-branch energy storage converter, which connects multiple battery groups to the energy storage converter in a distributed manner, reducing the parallel connection of battery clusters, reducing battery losses, and maximizing battery utilization.
Future Outlook
Global warming has become the world's biggest ecological problem, and the world is beginning to transition to "low carbon". my country has also proposed the "30·60" strategic goal. Currently, the most effective way for people to obtain renewable energy is through power generation. Therefore, energy storage is an indispensable part of achieving the "30·60" goal, and its market size is constantly growing. PCS is also one of the irreplaceable components in energy storage devices, presenting huge development opportunities.
The energy storage PCS market is currently quite large and has ample room for growth. PCS companies are no longer competing on hardware costs, but rather focusing on market penetration, customer service, and after-sales support, resulting in higher gross profit margins.
It is reported that in 2015, my country's PCS production was only 55,000 KW, and the average market price was around 1 yuan/W. By 2021, PCS production had increased to 1,947,500 KW, with an annual growth rate of over 80%, and the average market price had reached 1.135 yuan/W.
According to relevant organizations, the global PCS market is expected to reach 41 billion yuan by 2025, with an annual growth rate of about 60%.
