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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 illustrates the implementation and the study of a hybrid electric power system based on a 10kW-diesel generator associated to renewable energy sources including a 10kW wind turbine, 12kW photovoltaic, and 53Ah lithium-battery. These energy production sources are interfaced to micro-grid through three-level power electronics converters where the phase-to-phase RMS voltage is 600V. The variable...
This paper investigates a distributed consensus control design for heterogeneous energy storage devices in smart grids. Using communications between energy storage devices in the system, primary and secondary voltage/frequency control are achieved. The primary voltage and frequency synchronization is achieved by equally sharing the active and reactive powers among energy storage devices. The secondary...
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...
Communication data in the communication network of the islanded micro-grid can be disturbed by many methods, such as data attack or packet loss. In order to overtake the communication data disturbance (CDD), a new hierarchical control structure is proposed in the paper. Based on the concept of cyber physical system (CPS), the control structure is divided into two layers: cyber layer and physical layer...
A multi-time scale coordinated voltage control strategy in an islanded microgrid (MG) is proposed in this paper. The strategy is comprised of local voltage control of distributed generators (DGs), secondary voltage control (SVC) based on PI regulators and a proposed tertiary voltage control (TVC) strategy. A multi-objective function of the TVC is designed to achieve a compromise among three objectives:...
This paper proposes a frequency observer based control of a solar energy conversion system (SECS). The proposed control eliminates the DC offset and harmonics current and provides fundamental component of load current. The mathematical analysis of the control is corroborated and discussed in terms of filtering capabilities. Besides, capability of maximum power extraction, it integrates maximum extracted...
With the increasing penetration of renewable energy generations such as solar and wind power, negative impacts of the large-scale integration of renewable energy on the bulk grid cannot be ignored. Thus, grid integration testing of inverter-coupled renewable energy is essential. For this reason, a high power gird simulator capable of emulating various types of realistic grid conditions is needed for...
Voltage phase control is a novel field-weakening scheme for PMSM which was reported as more stable in high speed region. This paper provides a current ripple reduce method and a frequency-compensation method. The current ripple reduce method deals with the problem that the voltage phase control has bigger current ripple compared to the tradition method. The frequency-compensation method decreases...
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 an isolated DB LLC resonant converter with frequency adaptive phase-shift modulation control which overcomes the unity gain problem of conventional DB converter. The proposed control maintains the Zero Voltage Switching (ZVS) to all switches under all operating voltage and load variations. The control proposed for this circuit based on two control variables: switching frequency...
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...
The four-level Hybrid Clamped Converter (4L-HCC) is emerging as a promising DC/AC converter topology for high-efficiency medium-voltage drives. However, without proper control, the voltage fluctuation of the DC-link capacitors will be excessive, resulting in distorted AC current and stability issue in low frequency operation. In reality, the distorted current makes it impractical for motor drive during...
This paper presents a proportional harmonic power sharing (PHPS) control scheme to improve the voltage quality at point of common coupling (PCC) and share harmonic power simultaneously for an islanded microgrid. The proposed control strategy employs P+ multiple resonant controller, and P+ plus Q+-based improved droop control scheme to improve the voltage quality at the load bus. Additionally, the...
In a microgrid with distributed generation (DG) units, proper control of the grid interfacing inverter is critical to facilitate safe and stable operation of the system. The droop control mechanism is a widely accepted control method in a microgrid operation. However, a droop controller is unable to provide inertia support in such systems, and thus, cannot contribute in primary frequency control during...
Harmonic power can be shared by controlling the equivalent harmonic impedance of distributed generation (DG) units in islanded microgrids. This paper firstly reviews several methods for controlling the equivalent harmonic impedance of DGs and adopts the method based on resistive active power filter (R-APF). Then, a droop relationship between the equivalent harmonic impedance of DGs and their remaining...
Modular multilevel converters (MMCs), with the filter-less and transformer-less features, are considered as a promising topology for high-efficiency medium voltage (MV) high voltage (HV) drive systems. However, at low frequencies (< 30 Hz), a large current ripple flowing through the capacitors of each submodule will cause significant capacitor voltage fluctuation. This paper proposes an optimal...
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