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Micro grid is a latest concept for upcoming energy distribution system that enables, renewable energy integration. It generally combination of multiple distributed generations (DG's), that are usually connected to the grid through power inverters. During the islanding operation (autonomous mode) of grid, important task are to share the load demand among multiple parallel connected inverters proportionately,...
DC microgrid is becoming popular due to high efficiency, reliability and easy integration of renewable sources. Droop controller based distributed technique is used in dc microgrid for proportional power sharing among sources. However, due to interconnecting cable impedance, trade-off exists between power sharing accuracy and voltage regulation. Centralized controller achieves these objectives using...
Tightly controlled power electronic converters connected to a DC microgrid behave as Constant Power Loads (CPLs) and they have the potential to induce voltage oscillations at the DC bus. These oscillations become more probable in the presence of lightly damped L-C filters at the input of CPLs. The oscillations can be damped by inserting appropriate virtual impedances in the DC microgrid. It has been...
The capacitor voltage of an LC-filtered voltage source inverter is fed back for output-voltage regulation, which includes twin aspects of command tracking and output impedance control. The same feedback can also be used for active damping of filter resonance. Compared with the existing active damping techniques using filter inductor or capacitor current feedback, this technique saves a current sensor...
Low voltage distribution feeders have many imperfections. Their theoretical models give results far from actual values because of ignoring many extraneous factors. Small PV plants have a major share among renewable energy based Distributed Generators. They are interconnected with grid at Low Voltage (LV) distribution level which may adversely affect the voltage profile and phase balancing. Proper...
This paper presents a three-level ZSI for photovoltaic (PV) application to achieve single stage buck-boost (as per the solar variation). A single LC impedance network is used between DC voltage source (including PV array and a bidirectional buck-boost system) and neutral-point clamped (NPC) inverter. Alternative phase opposition and disposition (APOD) modulation technique with proper triplen offset...
In this paper, a modified structure for low-swing voltage-mode drivers in high-speed serial links is proposed, which offers lower static power and reduces the number of transistors compared to the conventional design. This structure adopts an impedance-modulated 2-tap equalizer with analog tap control. The impedance modulation technique is applied to only one input of the driver. Therefore, six transistors...
This paper presents controller design procedure for a fully silicon-carbide (SiC) based three-phase grid-connected PWM drive. The influence of the feedforward compensation for the presented setup is studied and the transfer function of the system with feedforward is derived and compared with the normal condition. The presented analytical model helps to calculate the parameters of the close-loop system...
This paper presents a new method of addressing the constant on time and minimal off time limitation of widely used COT variable frequency control. This is done by means of estimated capacitor current feedforward method. Ultrafast transient response is achieved with a new COT controller reacting much faster to output caps charge and discharge currents following a load transient step. A new output caps...
In this paper, an intelligent double closed loop controller for electric vehicle (EV) charging system in smart grid (SG) is proposed, in which it can perform seamless changeover from constant current (CC) to constant voltage (CV) charging stage. Moreover, it can perform CC and CV charging control separately without adding in an external logic. Experimental results will be provided in full paper submission...
This paper presents a control scheme combining SoC balancing and voltage/current regulation for a distributed battery system based on fly-back converters. In discharging operation, the proposed control scheme consists of two control loops. The first control loop is designed to regulate all battery terminal voltages to be identical, thus SoC imbalance issue is solved from the root. The other control...
Self-excited induction generator (SEIG) is more suitable for wind energy conversion in remote and windy areas but with varying terminal voltage. Terminal voltage has been regulated by adapting the value of excitation capacitance taking into account stator current.
The grid impedance ratio R/X value is the starting point for several conventional studies, such as DC power flow calculations. The conventional studies can be replaced with more generalized studies, in which the grid impedance ratio plays an important role. This paper presents a generalized droop control approach without the requisite estimation of the grid impedance ratio. Instead of performing large...
This paper proposes a synchronization control strategy based on voltage-controlled inverter and the synchronous speed is controllable. The proposed inverter can be simplified as a circuit consists of a controlled voltage source and equivalent impedance, the output voltage amplitude and frequency can be changed by adjusting the axial-regulators. The designed synchronization method has detection module...
This paper proposes a non-linear control strategy to curb for the non-linearities and parameter uncertainties for a grid connected system. Since the conventional techniques performance rely highly on the tuned controller gains prior to grid impedance, its performance deteriorates over time. To incorporate these non-linearities, an adaptive backstepping control strategy has been used subjecting to...
The aim of this study is to analyze and compare three droop controller schemes to regulate the operation of a microgrid. Three droop control schemes are selected because of their capability to regulate voltage, frequency and power sharing without using communication links and complex measurement systems. Specifically, the conventional droop controller and two of its variants are compared, the angular...
A voltage-mode (VM) transmitter which offers a wide operation range of 6-to-32 Gb/s, controllable pre-emphasis equalization and output voltage swing without altering output impedance, and a power supply scalability is presented. A quarter-rate clocking architecture is employed in order to maximize the scalability and energy efficiency across the various operating conditions. A P-over-N VM driver is...
In this paper, a droop control strategy is presented for accurate power sharing between parallel connected inverters in an AC microgrid in autonomous mode. The proposed strategy is based on the droop control techniques P-f/Q-V and P-V/Q-f, with a virtual impedance and using monitored quantities directly at the inverter. This droop control approach can be used in microgrids where communications are...
Droop control is an effective power sharing control scheme for islanding microgrid. With the load increasing, the microgrid may face overload challenge. Dispatch system should schedule energy storage system to provide power reserve or load shedding for preventing islanding microgrid black out. This paper proposes a coordinate control scheme for distributed generation (DG) units and active loads to...
This paper proposes an enhanced distributed generation (DG) unit with an adaptive virtual impedance control approach in order to solve the inaccurate reactive power sharing problem. The proposed method can adaptively regulate DG units with the aid of the equivalent impedance, and the mismatching problem of the feeder impedance is compensated by sharing the reactive power accurately. The proposed control...
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