A novel control method for dispersed converters providing dynamic frequency response

Active power converters are flexible and highly dynamic. Many power converters, as battery charging devices, use only a small part of their technical capabilities. This paper develops a new control method that combines the primary converter function with grid frequency control. Doing this, the frequency stability can be influenced positively, using the power converters control potential, without penetrating its primary functions under normal power system conditions. In case of severe frequency deviations, priority is given to this grid support functionality, which can significantly improve the security of supply. If the converter’s control algorithm does not take frequency stability aspects into consideration, the impact of thousands of these devices on the grid frequency stability will be negative. Electric and hybrid cars with battery storage and plug-in capabilities are used as an example for power conversion units. The impact of many cars, with the referred control method, on the UCTE (Union for the Co-ordination of Transmission of Electricity) grid frequency can be observed by simulations. Even a small percentage of electric cars can significantly influence the grid frequency after a power plant disconnection fault. No communication between network operator and converter is necessary for the basic grid supporting functions. Dispersed frequency support as suggested by the developed control method could be adopted as a requirement to future grid codes.