A new digital control of four‐leg inverters in the natural reference frame for renewable energy–based distributed generation

Abstract

Summary Nowadays, stand‐alone dispersed generation (DG) supplied from renewable energies is rapidly growing. In such a condition, four‐leg inverter can be considered as a successful option to supply unbalanced loads, especially in transformerless systems. In this paper, four‐leg inverter is modeled considering the fourth line inductor. The neutral (fourth) line inductor causes a high coupling through control variables in the natural reference frame. To avoid several transformations among reference frames, a new digital controller based on deadbeat (DB) theory is proposed in the natural reference frame to regulate the load voltages under coupled model. The proposed method offers simplicity, ease of digital implementation, and a fast dynamic response. Furthermore, a delay compensation procedure is also proposed to make the overall performance of the proposed DB controller better. Experimental tests based on a 3kW prototype are implemented to support the analytical analysis. Different tests under various single/three‐phase, nonlinear/linear, and unbalanced/balanced load conditions were performed, which confirm the excellent performance of the proposed control system.

A comparative performance study of a closed‐loop boost converter with classical and advanced controllers using simulation and real‐time experimentation

“…Boost converter is a step‐up chopper that provides larger output voltage compared to its input voltage. From prior work, 6‐28 it is observed that several types of linear, nonlinear, optimized, and advanced control approaches are already applied in Boost converters.…”

“…Modeling and advanced control architectures of switching converters which having nonminimum phase problem have been reported by Banerjee et al, Ling et al, Rana et al [20][21][22][23] Robust voltage control with wide parametric variations of switching converters for renewable energy applications are reported in prior works. 24,25 The comparison between different classical and advanced control methods like IMC, SMC for a Boost converter are discussed in Ghosh and Banerjee. 1 Advanced robustness studies, adaptive sliding mode based control and nonlinear dynamics analysis by varying different control parameters in switching converters are reported in recent literatures.…”

“…The stability analysis of switched mode converters with sliding‐mode and fuzzy‐logic based control techniques were discussed by D'Arco et al, 14 Labbe et al 15 and El Khateb et al 16 Online tuning of control parameters, and implementation of advanced control techniques in digital platform are introduced by Lai et al, 17 Ghosh et al, 18 Singh et al 19 for switching converters. Modeling and advanced control architectures of switching converters which having non‐minimum phase problem have been reported by Banerjee et al, Ling et al, Rana et al 20‐23 Robust voltage control with wide parametric variations of switching converters for renewable energy applications are reported in prior works 24,25 . The comparison between different classical and advanced control methods like IMC, SMC for a Boost converter are discussed in Ghosh and Banerjee 1 .…”

Continuous finite‐time control of four‐leg inverter through fast terminal sliding mode control

“…However, an unbalanced loading condition is an inevitable situation that occurs frequently in standalone applications. As a result, a fourth wire power system is mandatory to supply any unbalanced loads …”

Non‐linear integral higher‐order sliding mode controller design for islanded operations of T‐type three‐phase inverter‐interfaced distributed energy resources

“…The existing literature presents different control strategies [19–24] to control both islanded single‐ and three‐phase inverters. These strategies include the interconnection and damping assignment passivity‐based controller (IDA‐PBC) [19], model predictive control (MPC) [20], H three degrees of freedom (H‐3DOF) controller [21], deadbeat controller [22], modified linear active disturbance rejection control (MLADRC) [23], and unbalanced synchronous reference frame (USRF) controller [24]. These controllers are robust against uncertainties and have lower THDs while meeting the standard requirements.…”