Voltage controller

About: Voltage controller is a research topic. Over the lifetime, 6983 publications have been published within this topic receiving 74547 citations.

A Voltage and Frequency Droop Control Method for Parallel Inverters

Abstract: In this paper, a new control method for the parallel operation of inverters operating in an island grid or connected to an infinite bus is described. Frequency and voltage control, including mitigation of voltage harmonics, are achieved without the need for any common control circuitry or communication between inverters. Each inverter supplies a current that is the result of the voltage difference between a reference ac voltage source and the grid voltage across a virtual complex impedance. The reference ac voltage source is synchronized with the grid, with a phase shift, depending on the difference between rated and actual grid frequency. A detailed analysis shows that this approach has a superior behavior compared to existing methods, regarding the mitigation of voltage harmonics, short-circuit behavior and the effectiveness of the frequency and voltage control, as it takes the R to X line impedance ratio into account. Experiments show the behavior of the method for an inverter feeding a highly nonlinear load and during the connection of two parallel inverters in operation.

On dynamics and voltage control of the Modular Multilevel Converter

Abstract: This paper discusses the impact of modulation on stability issues of the Modular Multilevel Converter (M2C) The main idea is to describe the operation of this converter system mathematically, and suggest a control method that offers stable operation in the whole operation range A possible approach is to as­sume a continuous model, where all the modules in each arm are represented by variable voltage sources, and as a result, all pulse width modulation effects are disregarded After simulating this model and test­ing different control methods, useful conclusions on the operation of the M2C have been extracted The control methods are then implemented on a model with discrete half-bridge modules, in order to compare the results and to validate the continuous model approach When assuring that this model functions as expected, the goal of this paper is to conclude into a self-stabilizing voltage controller A controller is proposed, which eliminates circulating currents between the phase legs and balances the arm voltages regardless of the imposed alteranting current

Secondary Frequency and Voltage Control of Islanded Microgrids via Distributed Averaging

Abstract: In this paper, we present new distributed controllers for secondary frequency and voltage control in islanded microgrids. Inspired by techniques from cooperative control, the proposed controllers use localized information and nearest-neighbor communication to collectively perform secondary control actions. The frequency controller rapidly regulates the microgrid frequency to its nominal value while maintaining active power sharing among the distributed generators. Tuning of the voltage controller provides a simple and intuitive tradeoff between the conflicting goals of voltage regulation and reactive power sharing. Our designs require no knowledge of the microgrid topology, impedances, or loads. The distributed architecture allows for flexibility and redundancy, eliminating the need for a central microgrid controller. We provide a voltage stability analysis and present extensive experimental results validating our designs, verifying robust performance under communication failure and during plug-and-play operation.

Flexible control of small wind turbines with grid failure detection operating in stand-alone and grid-connected mode

Abstract: This paper presents the development and test of a flexible control strategy for an 11-kW wind turbine with a back-to-back power converter capable of working in both stand-alone and grid-connection mode. The stand-alone control is featured with a complex output voltage controller capable of handling nonlinear load and excess or deficit of generated power. Grid-connection mode with current control is also enabled for the case of isolated local grid involving other dispersed power generators such as other wind turbines or diesel generators. A novel automatic mode switch method based on a phase-locked loop controller is developed in order to detect the grid failure or recovery and switch the operation mode accordingly. A flexible digital signal processor (DSP) system that allows user-friendly code development and online tuning is used to implement and test the different control strategies. The back-to-back power conversion configuration is chosen where the generator converter uses a built-in standard flux vector control to control the speed of the turbine shaft while the grid-side converter uses a standard pulse-width modulation active rectifier control strategy implemented in a DSP controller. The design of the longitudinal conversion loss filter and of the involved PI-controllers are described in detail. Test results show the proposed methods works properly.

Power generator having a power selector and organic light emitting display device using the same

Abstract: A power generator includes a booster that boosts an input voltage supplied from a power supply unit and that supplies a boosted input voltage to an output terminal, a selector that selects one of the input voltage and a voltage at the output terminal as a selected voltage and supplies the selected voltage as an output voltage, a reference voltage generator that generates a reference voltage based on the output voltage, a comparator that compares a feedback voltage supplied from the booster and the reference voltage with each other, and a controller that controls the booster to output a chosen voltage from the output terminal according to a comparison result of the comparator.