Improved Direct Deadbeat Voltage Control with an Actively Damped Inductor-Capacitor Plant Model in an Islanded AC Microgrid

Jaehong Kim,Jitae Hong,Hongju Kim

doi:10.3390/en9110978

Jaehong Kim, Jitae Hong + Show 1 more

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https://doi.org/10.3390/en9110978

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Abstract

A direct deadbeat voltage control design method for inverter-based microgrid applications is proposed in this paper. When the inductor-capacitor (LC) filter output voltage is directly controlled using voltage source inverters (VSIs), the plant dynamics exhibit second-order resonant characteristics with a load current disturbance. To effectively damp the resonance caused by the output LC filter, an active damping strategy that does not cause additional energy loss is utilized. The proposed direct deadbeat voltage control law is devised from a detailed, actively damped LC plant model. The proposed deadbeat control method enhances voltage control performance owing to its better disturbance rejection capability than the conventional deadbeat or proportional-integral-based control methods. The most important advantage of the proposed deadbeat control method is that it makes the deadbeat control more robust by bringing discrete closed-loop poles closer to the origin. Simulation and experimental results are shown to verify the enhanced voltage control performance and stability of the proposed voltage control method.

Highlights

Due to an increased global interest in renewable energy systems and environmental concerns, distributed generators (DGs) are being installed increasingly
Islanded operation is essential for inverter-based DGs in microgrid or uninterruptible power supply (UPS) applications
There is a well-known limitation on voltage distortion in islanded DGs and UPS loads, and this has stimulated the development of a variety of different control schemes [1,2,9,10]

Summary

Introduction

Due to an increased global interest in renewable energy systems and environmental concerns, distributed generators (DGs) are being installed increasingly. The high penetration level of distributed energy resources (DERs) in electric power systems has led to a change in the requirements for ancillary services in local DGs such as islanded operation, interconnection control to the grid, and fault management functions [1,2,3,4,5,6]. Islanded operation is essential for inverter-based DGs in microgrid or uninterruptible power supply (UPS) applications. It requires a local voltage and frequency control function for local DGs, which simple grid-tied inverters do not have [3,7,8]. To improve voltage control performance, several high-performance feedback control schemes have been introduced, such as sliding mode control, robust control, model predictive control (MPC), and deadbeat control.

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