Predictive Optimal Matrix Converter Control for a Dynamic Voltage Restorer with Flywheel Energy Storage

Abstract

This paper presents a predictive optimal matrix converter controller for a flywheel energy storage system used as Dynamic Voltage Restorer (DVR). The flywheel energy storage device is based on a steel seamless tube mounted as a vertical axis flywheel to store kinetic energy. The motor/generator is a Permanent Magnet Synchronous Machine driven by the AC-AC Matrix Converter. The matrix control method uses a discrete-time model of the converter system to predict the expected values of the input and output currents for all the 27 possible vectors generated by the matrix converter. An optimal controller minimizes control errors using a weighted cost functional. The flywheel and control process was tested as a DVR to mitigate voltage sags and swells. Simulation results show that the DVR is able to compensate the critical load voltage without delays, voltage undershoots or overshoots, overcoming the input/output coupling of matrix converters.

Methods of source current reference generation for predictive control in a direct matrix converter

“…with q * s = 0, in order to have a unity power factor on the input side. Finally, (17) and (18) are combined into a single so-called cost function…”

“…Recent research has indicated the potential of model predictive control (MPC) techniques to monitor and reduce the high processing power required by microprocessors in many power electronics applications [17]. Predictive current control (PCC) can be described as a particular instance of MPC that takes into account the inherent discrete nature of the power converter using its switching states or voltage vectors and digital implementation [8,[17][18][19][20]. Several PCC methods used in MCs take into consideration the output current regulation and the reactive power minimisation on the source side, resulting in source currents that are instantaneously in phase with their respective phase voltage [8,19,21].…”

Review of model predictive control strategies for matrix converters

“…PCC and PTC. Other implementations, such as predictive voltage control [39, 40, 43, 44] and predictive reactive/active power control [20, 41] can be found in the literature as well, but they are not analysed in detail here. Moreover, other variations have been presented which cannot be directly included in the classifications of Fig.…”

“…Several research works, such as [22, 29–33, 37, 38, 40, 43, 45, 53, 59, 60], have discussed controlling this converter with an MPC scheme for a wide range of industrial areas including motor drive and grid‐connected applications. This control scheme contributes several advantages to the DMC.…”

“…Despite their improved control performance, these approaches impose complications and extra calculations to the control platform and might not be suitable for practical applications. Some leading strategies like model predictive control (MPC) have been newly proposed in order to simplify the control of MCs and provide fast and satisfactory performance in both transient and steady states [20–46]. Fig.…”