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A technical implementation variant of a singlephase voltage source inverter control system with sinusoidal pulse-width modulation based on target-oriented control with control actions frequency reduction providing specified nonlinear dynamic properties of the sys-tem and reduced requirements for computing resources of the microcontroller. The control system under consideration provides sinusoidal...
This paper proposes seamless frequency synchronization scheme for fast mode switching of parallel grid-connected inverters operated by droop control in stand-alone mode to grid-connected mode. The proposed scheme analyzes the phase difference between the grid and the inverter for fast frequency synchronization and predicts the synchronization time for frequency increase and decrease. By selecting...
This paper deals with the voltage and frequency restoration problem for a droop controlled islanded microgrid (MG). A consensus based distributed control is proposed for voltage/frequency restoration of MG which allows all the distributed generator (DG) unit voltage magnitude and operating frequency to converge to the nominal values even with different communication topologies. The proposed control...
In this paper the virtual synchronous generator control is introduced to MW-Scale Medium Voltage power system. The virtual synchronous generator with its inertia and damping features can be considered as an improvement for the communication-less control method (droop control). The MW-Scale Medium Voltage is generally preferable for its high power density, reduced current level, and reduced losses...
A muti resonant controller for high-frequency-link single-phase inverter is proposed in this paper. An equivalent circuit, which behave just like conventional unipolar PWM inverter is proposed for the converter. The dynamic model of the inverter, which built in continuous domain, is built. The inverter has the advantages of high efficiency, high power density, low-cost, low noise, bidirectional power...
A novel discrete sinusoidal signal integrator (DSSI) structure is proposed in this paper for single grid-tied inverters. The DSSI provides an adjustable gain and bandwidth at the expected frequency and a highly attenuated gain at other frequencies which make the DSSI based controllers obtain the zero steady-state error tracking performance of arbitrary frequencies. The performance of the conventional...
The voltage source inverters operating in islanded microgrid are used as sources of power similar to synchronous generators (SG) in conventional power system. Unlike synchronous generators, these inverters neither have a natural droop (P-f and Q-V) characteristics nor rotational inertia. The electrical time constant is much lesser than mechanical time constant and hence the load changes will show...
This paper presents a novel hybrid adaptive droop controller to simultaneously regulate both the AC-side and DC-side parameters for power electronic converters in single-phase Microgrids. The main contribution of this paper is to integrate the AC-side and DC-side controllers. Unlike previously presented control schemes, where the DC-bus is considered as an infinite bus or constant voltage bus, the...
Grid-connected Voltage Source Inverters (VSIs) equipped with LCL filters are attractive in utility applications for their better power quality features, while the inherent LCL resonance may limit the current control loop bandwidth or even threaten system stability. Simple but effective single-loop current control strategies have been studied for obtaining a stable system, where either the inverter-side...
In this paper, a three loop control strategy (TLCS) based on decoupled zero voltage switching angle (ZVSA) loop is proposed for a series-series (SS) compensated wireless power transmission (WPT) system. To realize constant current charging for EVs and ZVS operation of primary inverter, variable frequency and phase shift control strategy (VF-PSC) is adopted. However, the control variables that are...
Penetration levels of solar photovoltaic (PV) generation on the electric grid have increased in recent years. In the past, most PV installations have not included grid-support functionalities. But today, standards such as the upcoming revisions to IEEE 1547 recommend grid support and anti-islanding functions-including volt-var, frequency-watt, volt-watt, frequency/voltage ride-through, and other inverter...
Capacitor-current-feedback active damping method is commonly used in LCL-filtered grid-connected inverters, which attenuates the resonance peak by emulating a virtual resistor in parallel with the filter capacitor. Taking the digital control delay into account, the emulation component becomes frequency-dependent, and it will turn negative when the filter resonance frequency becomes higher than one-sixth...
This paper proposes a fixed frequency based sliding mode (SM) controller for transformer-less single phase inverter for photovoltaic (PV) application with active power decoupling minimizing the capacitance requirement. Unlike conventional power decoupling techniques in full bridge converters, the proposed technique incorporates a large sinusoidal swing of the half-bridge capacitor voltages and a limited...
Because of the differences in line impedances, parallel inverters with conventional droop control will have huge circulating current, which does not flow through the loads. To mitigate the circulating current, the research in this paper finds out that parallel-operated inverters should have the impedance in inverse proportion to their capacities, which is difficult to realize in practice. To meet...
In order to address the economical dispatch problem in cascaded microgrids, this digest proposes an optimal economical-sharing scheme via decentralized approach only with the local information. This overcomes the limitations of centralized control, where the central controller and external information exchange are needed. The frequency and current are used as carriers driven the distributed generators...
The increasing penetration of grid-connected RES systems, advanced control algorithms have been developed to operate under grid faults and fulfill strict requirements of the grid codes. In order to overcome this, the current controller performance is critical considering it as the inner control loop of any grid-connected RES system. Based on the resonant control concept, this paper presents a modified...
Fault current limiters (FCLs) are one class of solutions to cope with the upcoming challenges in microgrid protection. Considering high penetration of distributed generations (DGs) in microgrids, the necessity of designing cheap and effective FCL is getting higher. This paper attempts to fill this gap by proposing an embedded FCL operating based on modifying the secondary control of DGs. As this method...
In this paper a current-limiting droop control of grid-tied inverters that introduces virtual inertia and operates without a phase locked loop unit is proposed. The proposed controller inherits a self-synchronization function and can guarantee tight bounds for the inverter frequency. In addition, using nonlinear Lyapunov theory, it is analytically proven that the inverter current never violates a...
In order to offer a good power quality for end users in islanded microgrids, the power sharing between distributed generators (DGs) is the first challenge that must be ensured. In this paper, a droop control method based primary control for two parallel single-phase VSIs forming an islanded microgrid is presented. The proposed control consists of two DGs local controllers, where each controller includes...
A key objective to be fulfilled by distributed voltage source inverters working in parallel in islanded MicroGrids (MGs) is to ensure active power sharing while keeping the frequency at a desired setpoint. Recently, consensus-based control techniques have been applied at the secondary control level for active power sharing while correcting the frequency deviation that the droop control implemented...
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