In recent years, the global energy storage industry has been growing rapidly, with a shift in focus from battery hardware to the components of energy storage systems, especially the balance of system (BOS) components or energy storage inverters (power conversion systems, pCS). The applications of energy storage systems in advanced system management and grid integration are increasingly expanding.
Compared to conventional power sources, large-scale energy storage plants can quickly adapt to load fluctuations, offering multiple functions such as peak shaving, valley filling, frequency modulation, phase adjustment, and backup during outages. Additionally, they optimize the power supply structure, promote environmental sustainability, and enhance overall energy efficiency, thereby improving economic benefits. The key device, the energy storage inverter (pCS), consists of a bidirectional DC/AC inverter and a control unit. A crucial function of the pCS is to control the system to charge or discharge the battery based on monitoring commands, maintaining constant power or constant current. In engineering applications, the power ratings of pCS are continuously increasing, as is the voltage, presenting new testing challenges.
The DC side of the energy storage inverter is connected to the battery pack. To improve system efficiency and reduce losses, the DC voltage is gradually increasing, reaching levels of 1000V or even 1500V. This necessitates a high-power, high-voltage bidirectional DC power supply for simulating battery operation to test pCS performance. The ITECH6000C series is a regenerative bidirectional DC power supply that features battery simulation capabilities, with voltage ratings up to 2250V and a power density of 18KW in a 3U form factor. It can seamlessly switch between constant current (CC) and constant voltage (CV) modes, effectively addressing the voltage and current overshoot issues that arise during rapid switching in bidirectional DC/DC converters. It is a professional choice for simulating battery system testing.
In a specific case, a customer testing the pCS found that the DC side parameters were set to 200~600V/10~15A. In tests using another power supply (with non-adjustable loop speed), the output voltage and current oscillated (especially noticeable below 200V) due to the capacitance on the DC side of the pCS. By using the IT6000C and setting the CV loop speed to low, the voltage and current oscillations disappeared, achieving the desired testing outcomes. The IT6000C’s bidirectional operation met the user’s testing requirements.
In microgrids with renewable energy sources, one important application of energy storage systems is to smooth out the output fluctuations of wind and solar power, ensuring microgrid stability and reducing dependence on external grids. Besides the DC-AC structure, ITECH also provides testing solutions for DC-DC bidirectional converter modules within energy storage systems.
A user developed a 15KW bidirectional DC/DC single module with CC/Cp output modes, controlled via a host computer under various states including pre-charge, charging, and discharging.
The user purchased two IT6000C units to connect to both ends of the bidirectional DC-DC converter for charge and discharge testing. Taking the DUT in CC mode as an example: during charging, the IT6000C was set to CV priority with 1500V input and 48V low output. For testing, the IT6018C-2250-20 was set as the input source at 1500V and 10A output, while the IT6015C-80-360 was set as the load with CV=40V. During discharging, the IT6018C-80-360 was set to 60V as the input source, and the IT6018C-2250-20 was set to CV=1200V as the load. Observing the waveforms captured by the oscilloscope during the charge-discharge switching process showed that there was no overshoot in current when switching from discharge to charge.
The ITECH IT6000C series features built-in USB/CAN/LAN/digital I/O communication interfaces, with options for GPIB/analog & RS232. It supports independent edge settings for various modes, adjustable rise and fall times, and includes a solar panel I-V curve simulation function, as well as 20 standard voltage curves for automotive power networks. It holds promising applications in industries requiring large power source-load demands, such as photovoltaics, energy storage, and automotive lithium batteries.
