Multifunctional Control Strategy for Asymmetrical Cascaded H-Bridge Inverter in Microgrid Applications

Abstract

A multifunctional control strategy for a singlephase Asymmetrical Cascaded H-Bridge Multilevel Inverter (ACHMI), suitable for microgrid systems with nonlinear loads, is presented. The primary advantage of ACHMI is to produce a staircase output voltage with low harmonic content utilizing unequal DC voltages on the individual H-bridge cells. In gridconnected mode of operation, the control strategy of the ACHMI is based on the Conservative Power Theory (CPT), providing selective disturbing current compensation besides injecting its available energy. In autonomous mode of operation, two different control methods along with a damping resistor in the filter circuit are developed for regulation of the ACHMI instantaneous output voltage in a variety of load conditions. The first method is a single-loop voltage control scheme without the need of any current measurement. The second one is multi-loop voltage control scheme with a load current feed-forward compensation strategy and preservation of the grid-connected current control scheme. The steady state response and stability of both voltage control schemes are analyzed, and based on the application requirement, the control schemes are implemented individually. The effectiveness of each control strategy is experimentally verified using a hardware-in-the-loop (HIL) setup with the control algorithm implemented in the TMSF28335 DSP microcontroller.

Grid-Connected Symmetrical Cascaded Multilevel Converter for Power Quality Improvement

“…Unequal magnitudes of the dc voltage sources in Fig. 1 would result in an asymmetric CHMI with an increased number of output levels generated by the same number of H-bridge cells [28].…”

“…The CPT [14] allows for the decomposition of the instantaneous currents into different orthogonal current terms, valid for single-and multiphase systems, independent of the voltage conditions. Such components can be applied as reference signals to shunt active filters [15], [16], multifunctional converters [28], [36], [37], or for the design of filter elements, such as semiconductor switches, inductors, and capacitors. Moreover, the resulting compensation strategies are highly flexible since the decompositions allow for the selective identification and minimization of different disruptive effects (nonlinearities, unbalances, and reactive power).…”

Power factor angle consistency control for decentralised power sharing in cascaded‐type microgrid

“…The microgrid concept is a quite appealing alternative to account for this trend [3][4][5]. In microgrid, DGs are commonly connected by power electronic converters in paralleled or cascaded manner [6,7]. Accurate power sharing and system stability are the core problems in microgrid research.…”

A series-parallel PV-storage independent microgrid and its decentralized control

“…The series PV‐storage integrated MG shown in Figure C, which consists of cascaded H‐bridge (CHB) converters, has the capability of supplying a higher voltage levels . The CHB converter is considered as one potential candidate for PV power generation.…”