Author: Jonathan Bullick, Sales Manager, KEB America, Inc.
KEB’s tech expertise enabled the creation of Energy Recovery Systems (ERS), also known as Energy Conversion Systems (ECS), electronic systems that control turbomachinery and convert energy from some sort of process. This involves converting high-frequency electrical power to something that can be used on the mains or building power. Typical processes could be geothermal, air separation, or waste heat recovery.
A KEB load drive controls the speed of the generator, while the set speed is controlled via a master control system. The load drive regulates the generator speed once the process gas is introduced, and as energy is returned to the electrical system, the Active Front End (AFE) is able to return it to the building power or utility.
In High-speed motor/generator applications, control instabilities and imperfections that are masked at low speeds can become critical at high speeds. The turbomachinery used in energy recovery processes typically use special purpose high-speed generators, which are normally equipped with special magnetic bearings or airfoil bearings and can spin in excess of 100,000 rpm. The advantage of using high-speed generators is that they’re extremely compact, efficient, and have a high power density. KEB drives are capable of outputting frequencies up to 1,600Hz which is required to run these generators/motors.
The SCL-optimised generator control creates less rotor heating and increased energy output and offers plenty of flexibility with parameter adjustments, which allows the KEB system to work with a variety of different generator types and designs characteristics.
KEB offers both air- and water-cooled drives. Liquid-cooled drives offer a number of advantages, particularly if the systems are to be installed at high altitudes or in high ambient temperatures. Air-cooled versions are often preferred for their simplicity. KEB can provide both solutions, depending on the application requirements.
KEB’s energy recovery concept can be easily scaled across different power ranges. With optimisation, it becomes easier to make a business case for investing in an energy conversion system. KEB offers Active Front End (AFE) technology with low harmonic distortion (THiD). AFE is of interest to those looking to generate power back to the mains. The clean generated power will not create issues for other electrical loads and the power factor can even be compensated for as required.
KEB offers a standalone drive panel that includes all the drive, filter, and control necessary to control the motor-generator. A C6 HMI LC provides drive diagnostics and the ability to make parameter adjustments. The HMIs are delivered with a CONNECT runtime, which means the systems can provide remote access. This gives the option to provide remote maintenance and future PLC upgrades.
The KEB conversion system includes a grid protection relay and an EMI filter to mitigate high-frequency noise. There is also provision to detect an emergency situation and then safely disconnect the system. These are features that would need to be considered and implemented anyway. In this case, they are already engineered by KEB into a system that can be easily integrated into the process and quickly implemented into a customer system.