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This paper present a method to estimate the output current or voltage in the primary-side of a two-transmitter inductive wireless power transfer system, which has been introduced to achieve the continuity of power transfer, without any direct measurement on the receiver coil and load conditions. The proposal can ensure the continuity and stability of charging in dynamic wireless power transfer system...
Piezoelectric actuator connected to the digital synthetic-impedance device (DSID) represents a modern approach for vibration damping. For efficient use of DSID there are requirements for low input-to-output time delay and high output impedance of the DSID's main part - the voltage controlled current source. In this paper we present two types of these analogue front-ends. The first discussed circuit...
This paper presents a comparative analysis of different shoot through control schemes employed in Z-source inverters. Z-source inverter provides a single stage power conversion topology which can give both voltage buck and boost properties. This paper also gives an insight on the working of Z-source inverter by utilization of shoot through forbidden states. These states are utilized by implementing...
Parallel connection of inverter modules is a solution to increase reliability, efficiency and redundancy of inverters in Micro-Grid system. Proper load sharing among parallel inverters is a key point. The circulating current among the inverters can greatly reduce the efficiency or even cause instability of the system. In this paper, a control strategy for improving the load sharing performance in...
Photovoltaic (PV) energy is one of the most important energy resource since it is clean, pollution free and inexhaustible. The number of installed PV power plants is steadily increasing worldwide. This poses new challenges to solar inverters to stabilize the electric grid. New control strategies must be developed to fulfil the requirements of the grid operators.
In this paper a comparison between grid-feeding and grid-supporting inverters is shown based on simulation and measurement of inverter output impedances. The output impedance of a grid-feeding inverter with current control shows capacitive behavior compared to inductive behavior of a grid-supporting inverter with voltage control.
This paper develops the droop control strategy to connect multiple different types of converters in parallel in an isolated single-phase low voltage microgrid. First, the traditional droop control for low voltage microgrids is explained. Then three different types of converters in a microgrid are described, and different droop equations are proposed for each converter to overcome the line impedance...
This paper proposes a technique to perform the multifunctional use of current controlled voltage source inverters used primarily as interface between renewable energy sources and the grid utility. The strategy adopted doesn't demand sensing the grid current neither the load current. Instead, the reference signal for compensation purpose is obtained by filtering the harmonics components of the voltage...
Adaptive voltage positioning (AVP) technique has been widely used in voltage regulator (VR) applications. In this paper, a digitally controlled buck converter with the proposed current sensor-less AVP technique is presented. Without the need for sensing or sampling the loading condition, the proposed control architecture utilizes the error signal of the digitalized controller to obtain the current...
Since the concept that, inverters can controlled to behave like a synchronous generator "Virtual Synchronous Generator" has been proposed, the virtual synchronous generator started to become the mainstream control of distributed generators connected distributed system. This concept simulates the frequency and voltage regulation of synchronous generator to improve the overall stability in...
The renewable energy sources like wind, solar, and fuel cell sources has widely used in the smart gird to reduce the power loss in the conventional central generation. However, these sources usually operated at low output voltage levels. This paper proposes single phase bidirectional inverter is used for voltage regulation which gives less voltage ripple. Proposed quasi - Y source converter has many...
Motivated by the distributed control strategy of a multi-agent system, this paper presents a distributed voltage and frequency synchronization schemes for an AC microgrid (MG). For a low voltage MG, the line impedance between the distributed generator (DG) units are predominantly resistive, therefore the existing droop control approach i.e. P — ω and Q — v droop yields transients and poor stability...
The objective of this paper is to provide a method for steady-state short-circuit analysis in power networks with distributed energy resources (DERs). For this purpose, we suggest an approach that takes into account the impact of current controlled DERs in the fault analysis. The current controlled DER has some characteristics that we should consider–1) DER's large filter inductance and 2) the limit...
This paper describes how a linear relationship between control voltage and transmission coefficient can be obtained for a PIN diode biphase attenuator. This linearisation comes out from a theoretical study of the attenuator. Results given here, are obtained for a microstrip biphase attenuator optimised at 1.59 GHz.
In this paper, a control scheme for stand-alone voltage source inverters using resonant controllers in the 2-phase stationary frame of reference with a zero sequence controller is proposed. The proposed control scheme reduces the number of resonant controllers while achieves the same performance as existing control methods. The total harmonic distortion (THD) of the output voltage is improved over...
An online transmission line impedance parameter identification method is proposed for distributed generation (DG) in this paper. The droop control is adopted for local controller of DG units, which aims to realize accurate power sharing. The impedance parameter model is established by producing a small perturbation on load power after transforming voltage and current to dq coordinate, thus the line...
This paper presents new controller using FPGA and Real-Time Processor based on LabVIEW Programming that can be detected phenomena of Induction Generator (IG) isolated from grid. Advantage of controller can be monitoring voltage, current signal and reducing effect of buildup voltage of IG after disconnecting form grid system by connecting the impedance to IG terminal. The results demonstrate that the...
The paper considers main hardware designed for improvement of electromagnetic compatibility arc furnaces. The furnace power mode is proven to be of a dramatically variable and non-stable nature affecting economic performance of the furnace adversely. The authors provide a detailed description of the method stabilizing power parameters of the arc furnace due to a contactless and high-speed control...
This paper presents a Lyapunov-function based control approach with cascaded proportional-resonant (PR) controller for single-phase grid-tied LCL-filtered quasi-Z-source inverter (qZSI). The proposed control approach guarantees the global stability of the closed-loop system and zero steady-state error in the grid current. The reference values for the inverter current and capacitor voltage are generated...
This paper proposes an optimised design approach for Multi-Modular (M-M), single-phase UPS inverters system. The Voltage Source Inverters (VSIs) have low output impedance for good voltage regulation, which conflict with the requirement of high impedance in the parallel configuration to restrain Inter-Modular (I-M) circulating currents. Conventional dual-loop approach of Proportional-Resonant (PR)...
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