Control and filter design of three-phase inverters for high power quality grid connection

Electric Power Systems Research

Prodanović

2007

Self Cite

295

195

Section: Grid-connected Modementioning

confidence: 99%

Control of inverter-based micro-grids

Electric Power Systems Research

Prodanović

2007

Self Cite

295

195

“…A schematic of an inverter arranged in current-controlled mode is shown in fig. 1 and follows the proposal made in [22]. The objective is to regulate real and reactive power to follow reference values (P * and Q * ).…”

Section: Vsi In Current Control Modementioning

confidence: 99%

State-space model of grid-connected inverters under current control mode

Kroutikova

Hernandez-Aramburo

IET Electr. Power Appl.

2007

Self Cite

164

The growth of distributed generation has led to distribution systems with a mixture of rotating machine generators and inverter interfaced generators. The stability of such networks needs to be studied through analysis of state-space models and so suitable models of inverters are needed to complement the well established models of rotating machines. Just as machine models include features such as automatic voltage regulators and wash-out functions so too should the inverter model include phase-locking functions and internal control loops.This paper develops the model for voltage source inverters with an internal current control loop, an outer power regulation loop, a measurement of average power and a phase-locked loop. The model is presented in detail and is formed with a state-vector similar to that used for rotating machines. The model includes non-linear terms but can be linearised about an operating point. The state-space model is verified against a component-level time-step simulation in Simulink/PLECS.

“…By using a realistic assumption for the switching frequency of 8 kHz and applying the estimators to improve the control bandwidth as in [23] and [24], the closed-loop response of the internal current control can be approximated in the continuous time domain as in (18)…”

Section: Example Of Distributed Control Of a Multiple Inverter Systemmentioning

confidence: 99%

High-Quality Power Generation Through Distributed Control of a Power Park Microgrid

Prodanović

IEEE Trans. Ind. Electron.

2006

Self Cite

288

127

Abstract-Inverters are a necessary interface for several forms of distributed generation (DG) and where they form a microgrid they have the potential to offer high power quality. The challenge is to coordinate the actions of a group of inverters so that they offer the level of power quality known to be possible from fast local control of a single inverter. The case examined here is a power park of several inverter-based DG in relatively close proximity. A basic requirement is that the inverters regulate the grid voltage and share the real and reactive power demands according to their ratings. In small girds with high proportions of nonlinear and unbalanced loads it is also important to actively control the waveform quality in terms of harmonics, transient disturbances, and balance. Further, it is important that these duties are shared equally between the units rather than having one master unit taking the lead in the voltage control function. A constraint faced in designing a sharing system is the limited bandwidth of signal communication even over distances of a few meters. A control method is proposed that separates the control tasks in the frequency domain. Power sharing and voltage regulation are controlled centrally and commands are distributed through a low-bandwidth communication link. Waveform quality functions are controlled in high bandwidth controllers distributed to each local inverter. Experimental tests on a grid of three 10-kVA inverters are used to show that the method fully exploits the inherent fast response of the inverters while also ensuring voltage balance even with extreme load imbalance. It is shown that circulating currents are avoided during steady state and transients.