November 17, 2021
Next Generation Power Conversion Systems for Energy Storage
It is time to start talking about the next generation of Power Conversion Systems for battery energy storage. As the North American market moves toward longer duration storage tied to renewable energy the stage is set for the next generation of power converters. With the evolution in information technology the next generation will be smarter, faster and more resilient as well as more secure. But they may also look very different from the devices that are available on the market today. As anyone with any experience in the solar market knows, when string inverters entered into the Utility Scale PV sector, the demand for Centralized inverters plummeted and the market landscape changed overnight. It isn’t difficult to imagine a similar disruption in the energy storage sector. A new generation of inverters that combine all of the functions to manage PV+BESS with a single device is emerging. The next generation of Power Conversion Systems will help increase the power density of a forty-foot container from 2.8MW today, through innovations in power module architecture drawing on architectures in Medium and High Voltage drives. This will reduce the number of units/MW that need to be installed. The control platform on the units in the future will be able to make real time decisions about energy transactions to maximize revenues as well as manage a diverse set of grid services so that owners can get the most usage out of their systems and never have to worry about them getting stranded.
One of the key innovations on the market today is the DC/DC power unit with galvanic insulation which protects the batteries from common mode stresses enhancing the reliability of the system as well as the safety. In addition, the module offers higher efficiency and simplifies the overall system design, significantly reducing installation and commissioning for a truly plug and play experience in the field. Customers have to bring their assets on-line as quickly as possible to start generating revenues. Simplifying the system reduces installation time and ensures predictable performance. The device is also being used in Hybrid Power Quality systems combining Battery Energy Storage with Statcom devices. The hybrid systems are not only able to support typical functions like voltage variations, frequency regulation and black start in island mode but are also able to provide reactive and active power as well as harmonics cancellation.
Another area of innovation for overall system design is in the field of transformer-less technology. With advances in semiconductors and control technologies power devices can be modulated for a power factor of one with ultra-low harmonics so that the only transformer needed is the step-up or step-down transformer for grid connection and there is no need for harmonic filters. This innovation not only reduces CAPEX but also improves efficiency as transformers generally account for 2-3% of overall system losses.
The final area of innovation is in the field of real time control of big data. Power Management Systems for Energy Storage must manage millions of data points and react to energy and power demands in less than 120 milli-seconds and the race is on to reduce this time even further. This translates into greater accuracy in energy control as well as real-time diagnostics and troubleshooting, not to mention Virtual Power Plant functions that allow decentralized assets to be managed from a single control center. Customers depend on robust Energy and Power Management Systems, preferably based on real-time industrial automation platforms that have been used in thousands of mills and factories across the globe for greater reliability. These types of systems are extremely robust and usually use standard off-the-shelf hardware to facilitate maintenance and avoid issues of component obsolescence. R&D efforts are constantly enhancing the speed and performance of algorithms with a focused on optimization. An algorithm is robust if it can achieve anywhere from 4 to 10% better performance in the state-of-health of the batteries which means it is able to improve on the battery life cycle in terms of less degradation, offering Customers better assurances that the system will perform over time, with the additional benefit of reducing warranty risks. Work on using second life batteries for energy storage is pushing the development of even more innovative algorithms that can manage data on the state-of-health and charging profile down to the single module for even better overall performance of the energy storage systems.
About Nidec Industrial Solutions
Nidec Industrial Solutions is Europe’s top Utility Scale Battery Energy Storage providers and has ranked amongst the world’s top three for the past five years. With a manufacturing base in Cleveland, Ohio the group is now present in North America and just recently commissioned a large Utility scale BESS project for Enel Green Power in Lily, Texas.