DC-Link Voltage Control Strategy for Three-Phase Back-to-Back Active Power Conditioners

Abstract

The objective of this paper is to propose a threephase back-to-back active power conditioner (APC) with dc-link voltage control strategies for micro-grid applications. The demanded active and reactive power of the APC via bidirectional power flow control can help to regulate the frequency and voltage of micro-grids to achieve high stability. Moreover, the dc-link capacitor is the necessary component of the back-to-back APC for power decoupling and power flow balancing. In order to provide the ability to improve the power quality and stability of micro-grids as well as to reduce the dclink capacitance, two dc-link voltage control methods are developed: a) optimal ac line current regulation strategy and b) dynamic dc-link voltage regulation (DDVR) strategy. Under steady state, the proposed optimal ac line current regulation strategy is able to minimize the change of the input current variation as well as to achieve the dc-link regulation in one 60Hz cycle. As soon as an abrupt or continuous power change occurs, the dc-link voltage of the APC will be changed dramatically and the voltage protection could easily be triggered. Therefore, a novel DDVR strategy is proposed in order to prevent the false alarm as well as to reduce the required dc-link capacitance. Thorough mathematical equations corresponding to the proposed dc-link voltage control strategy are presented which can be used to determine the appropriate dc-link capacitance. Computer simulations and hardware experiments obtained from a 5 kVA prototype circuit demonstrate the feasibility and performance of the proposed APC.

Control and analysis of a 3‐level diode‐clamped split source inverter in the applications of grid‐tied photovoltaic systems

“…So, the dc‐link voltage should revert to the set value to allow the maximum power for the grid or to the load. The mathematical equation to calculate the dc‐link voltage reference is 18,19 : where U abc , DCSSI is the RMS value of DCSSI voltage. In general, the dc‐link voltage reference should be greater than or equal to rms value of the inverter terminal voltage 24…”

“…The deviation in energy can be represented as 19,26 where C is the total capacitance, δ E is the energy received by capacitor. …”

A Review on Optimization and Control Methods Used to Provide Transient Stability in Microgrids

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Discrete-Time DC-Link Voltage and Current Control of a Grid-Connected Inverter with LCL-Filter and Very Small DC-Link Capacitance

“…As an additional resistor increases losses and costs, in this paper, an active damping method is used and incorporated in controller design. [3] 80 µF 750 V 5 kHz 15 kV A L [8] 470 µF ≥565 V 5 kHz 5.5 kV A L [9] 470 µF 400-450 V 20 kHz 1.8 kW LCL [10] 800 µF 235-450 V 20 kHz 1 kW LCL [11] 2 • 500 µF 600 V 10 kHz 2.4 kW LCL [12] 1 000 µF 600 V -2 kW (jumps) LCL [13] 1 500 µF 700 V -12 kW L [14] 1 500 µF 680 V 10 kHz 15 kV A LCL [15] 1 500 µF 800 V -6 kW LCL [16] 2 800 µF 400 V 20 kHz 5 kV A L [17] 6 000 µF 700 V -25 kW LCL [18] 23,000 µF 1 200 V 20 kHz 1.5 MW L [19] 25,000 µF 1 750 V 4 kHz 2.5 MW LCL [20] 25,000 µF 500 V 15 kHz 7.5 kW LCL [21] 300,000 µF 700 V -1.5 MW L [22] 1 100 µF 150 V 20 kHz ≤1 kW L [23] 1 100 µF 800 V 10 kHz 20 kV A L [24] 2 000 µF 680 V 10 kHz 15 kV A LCL [25] 3 300 µF 750 V 5 kHz 17. 5…”