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Energy storage system components:

detailed explanation of power storage converter (PCS)

 

 

Under the background of global energy structure transformation, energy storage technology, as a key means to solve the imbalance of energy supply and demand and improve energy utilization efficiency, is facing unprecedented development opportunities. As the core equipment of energy storage system, the performance of power conversion system (PCS) directly affects the operating efficiency and reliability of energy storage system.

 

01PCS: The “Energy Router” of Energy Storage System

The power storage converter (PCS) is a key device that connects the energy storage battery and the per grid/load. Its main function is to achieve two-way conversion and control of electric energy. It accurately regulates the battery charging and discharging process according to system requirements to ensure efficient and stable operation of the energy storage system. In modern energy systems, the role of PCS is similar to that of an "energy router", which can flexibly allocate the flow of electric energy to meet energy needs in different scenarios.

 

Working principle: PCS is based on the principle of a controllable four-quadrant converter on the AC and DC sides. It implements a constant power or constant current control strategy to achieve a two-way flow of electric energy. On the grid side, PCS charges or discharges according to grid demand; on the battery side, it accurately controls the battery's charge and discharge current and voltage to ensure the battery's safe and efficient operation. For example, when the grid load is low, PCS can store electric energy in the battery; when the load is high, PCS can release the electric energy in the battery to the grid to achieve optimal energy allocation.、

 

02 Technical architecture: core components of PCS

1. Power Electronics

Power electronic devices are the core of PCS, mainly including thyristors (SCR), insulated gate bipolar transistors (IGBT), metal oxide semiconductor field effect transistors (MOSFET), etc. These devices achieve efficient conversion and control of electric energy by controlling the switching state of current and voltage. In recent years, with the application of wide bandgap semiconductor materials (such as silicon carbide and gallium nitride), the performance of power electronic devices has been continuously improved, further improving the conversion efficiency and power density of PCS.

 

2. Control circuit

The control circuit is the "brain" of the PCS, responsible for signal acquisition, processing and control algorithm execution. The signal acquisition module is responsible for collecting key signals such as current, voltage, and temperature; the processing module filters and preprocesses the collected signals; the control algorithm module calculates accurate control signals based on the processed signals to drive the switching action of power electronic devices. Advanced control algorithms can achieve more accurate charge and discharge control and improve the overall performance of the system.

 

3. Electrical connection components

Electrical connection components are important components of PCS, including cables, plugs and sockets, and terminal blocks. These components are required to have good conductivity and reliable contact performance to ensure stable transmission of electrical energy. In practical applications, the quality of electrical connection components directly affects the operational reliability and safety of PCS, so their quality needs to be strictly controlled.

 

03 Working mode: flexible application of PCS

1. On Grid mode

In on grid mode, PCS realizes bidirectional energy conversion between battery packs and the grid. It can charge the battery during the low load period of the grid and release the battery's power to the grid during the peak period to achieve "peak-valley arbitrage". In addition, PCS can also perform active and reactive power compensation when the power quality is poor to improve the stability of the grid. For example, when the grid voltage fluctuates or the frequency deviation is large, PCS can adjust the output power and stabilize the grid parameters through rapid response.

 

2. Off Grid mode

In off-grid mode, PCS is disconnected from the main grid, providing AC power to some local loads and independently stabilizing voltage and frequency. In this mode, PCS becomes the core power source of the microgrid or off-grid system, ensuring continuous power supply to critical loads. For example, in scenarios where there is no access to the main grid, such as remote areas or islands, off-grid PCS can provide reliable power supply to local residents or businesses.

 

3. Hy Grid mode

Hy grid mode is an advanced operating mode of PCS, which can flexibly switch between grid-connected and off-grid modes. In this mode, PCS can automatically select the optimal operating mode according to the grid conditions and system requirements to improve the reliability and flexibility of the system. For example, during grid failure or maintenance, PCS can automatically switch to off-grid mode to ensure the power supply of local loads; after the grid returns to normal, it can seamlessly switch back to grid-connected mode.

 

04 Selection points: precise matching of PCS

1. Power and capacity

The power and capacity of PCS should be determined according to the actual load demand in the microgrid, the capacity of distributed generation energy, and the scale and application requirements of the energy storage system. At the same time, it is also necessary to select the appropriate converter type in combination with the voltage level of the project. For example, for a small distributed energy storage system, a low-power, high-efficiency PCS can be selected; while for a large energy storage power station, a high-power, high-capacity PCS is required to meet the demand.

2. Transformer ratio

The transformer ratio is determined by the battery voltage range and must be matched with the voltage of the energy storage battery system. Reasonable transformer ratio selection can improve the conversion efficiency of the system and reduce energy loss. In actual selection, the transformer ratio should be accurately calculated based on the nominal voltage of the battery and the rated voltage of the system to ensure stable operation of the system.

 

3.Reliability

Reliability is a basic requirement for energy storage converters. When selecting, PCS products with high reliability design should be given priority, such as redundant design and high-quality components, to ensure stable operation of the system. For example, a PCS with dual power supply redundancy design can automatically switch to another power supply when one power supply fails to ensure continuous operation of the equipment.

 

4. Efficiency

An efficient PCS can reduce losses during energy conversion and lower operating costs. When selecting a model, you should pay attention to the efficiency performance of the PCS under different working conditions and choose a high-efficiency product. For example, some advanced PCS can achieve a conversion efficiency of more than 98% at full load and maintain a high efficiency at light load, thereby effectively reducing system losses.

 

5. Communication and remote monitoring functions

Modern energy storage systems usually need to have communication and remote monitoring functions in order to monitor and remotely control the operating status of the PCS in real time. When selecting a product, priority should be given to PCS products that support standard communication protocols (such as Modbus, Profibus, etc.) and have complete remote monitoring functions. Through remote monitoring, operation and maintenance personnel can obtain the operating data of the equipment in real time, discover and handle faults in a timely manner, and improve the operation and maintenance efficiency of the system.

 

6. Cost

Under the premise of meeting performance requirements, PCS products with high cost performance should be selected as much as possible. When selecting, factors such as equipment purchase cost, operation and maintenance cost, and replacement cost should be comprehensively considered to select the solution with the lowest life cycle cost. For example, although the initial purchase cost of high-performance PCS products is high, if they have high operating efficiency and good reliability, in the long run, they may bring lower operation and maintenance costs and higher economic benefits.

 

05 Application scenario: Multiple values of PCS

1. New energy power generation supporting

In photovoltaic, wind power and other renewable energy power generation scenarios, PCS can smooth the volatility of renewable energy and improve the absorption capacity of renewable energy. Through the charge and discharge control of PCS, real-time matching of renewable energy power generation and grid load can be achieved. For example, in a photovoltaic power station, PCS can store excess electricity in batteries when there is sufficient sunlight during the day, and release electricity at night or on cloudy days, thereby improving the stability and reliability of the photovoltaic power station.

 

2. Microgrid and off-grid systems

In microgrids or off-grid systems, PCS, as a core power supply device, can ensure continuous power supply to key loads. Through the flexible control of PCS, efficient and stable operation of microgrids or off-grid systems can be achieved. For example, in island microgrids, PCS can work with diesel generators, solar panels and other equipment to optimize energy configuration, reduce dependence on diesel generators, and reduce operating costs.

 

3. Grid ancillary services

PCS can participate in the auxiliary service market of the power grid, such as frequency regulation and peak regulation. Through the rapid response and precise control of PCS, the stability and reliability of the power grid can be improved. For example, in the power grid frequency regulation service, PCS can quickly adjust the charging and discharging power according to the changes in the power grid frequency to stabilize the power grid frequency.

 

4. Distributed energy storage system

In a distributed energy storage system, PCS can realize centralized control and optimized scheduling of multiple energy storage units. Through the coordinated control of PCS, the overall performance and economic benefits of the distributed energy storage system can be improved. For example, in a distributed energy storage system of a commercial building, PCS can flexibly adjust the charging and discharging strategy of the energy storage unit according to the building's power load and electricity price changes, achieving "peak shaving and valley filling" and reducing electricity costs.

 

06 Future Trends: Technological Evolution of PCS

1. High efficiency and high density

With the continuous advancement of power electronic device technology, the efficiency of PCS will be further improved, and the power density will continue to increase, which will enable PCS to achieve higher power output with smaller size and weight.

 

2. Intelligence and Automation

The future PCS will be more intelligent and automated. By integrating advanced control algorithms and artificial intelligence technology, PCS can achieve functions such as adaptive control and fault prediction, further improving the reliability and efficiency of the system.

 

3. Multifunctional integration

In the future, PCS will develop towards multifunctional integration. In addition to the basic charging and discharging control functions, PCS will also integrate power quality management, reactive power compensation and other functions to achieve multiple uses of one machine and enhance the comprehensive value of the equipment.

 

07 Conclusion: PCS opens up a new energy future

With the continuous advancement of technology and the continuous expansion of application scenarios, PCS will usher in a broader development prospect. In the future energy system, PCS will become the key link connecting new energy, power grid and load, providing solid support for the sustainable development of human society.