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This paper analyses the behaviour of a full-converter wind generation system with a back-to-back conversion structure using Neutral Point Clamped (NPC) converters during network faults. A Permanent Magnet Synchronous Generator (PMSG) is used as the generator. The main problems of this structure during voltage sags are firstly, the accumulation of power in the DC-link due to the reduction of power...
The rate at which large variable speed wind farms are being developed had increased rapidly as the demand for green energy has grown. With this increase in distributed energy penetration into power networks, the main focus must be on power quality (Voltage Quality and Supply Reliability). However, new grid codes require wind energy generating systems to ride through grid faults, and at the same time...
This paper aims at a power factor corrected (PFC) buck bridge DC-DC converter for a permanent magnet brushless DC motor (PMBLDCM) for an air conditioner. This PFC converter is fed from a single-phase AC mains through a diode bridge rectifier (DBR) and connected to a voltage source inverter (VSI) feeding the PMBLDCM. The Speed of the proposed PMBLDCM drive is controlled to improve efficiency of the...
This paper presents a STATCOM with a self-oscillating bidirectional dc-dc converter for interfacing battery energy storage in a stand-alone induction generator system. The self-oscillation mode is based on relay feedback control with hysteresis. To reduce the output current ripple, an LCL filter is connected between the half bridge of this dc-dc converter and the energy storage system. The other side...
The paper presents an emerging technology of electricity generation based on decoupled theory. The decoupled generation system operates in wide speed range and control strategy is oriented to select regions of high efficiency of the driving engine. This system is used to operate in parallel with renewable energy source RES, which is unstable and not reliable. In case of high power available from the...
It is proposed in this article an optimal solution to improve the transient behavior of doubly-fed induction generators in wind parks connected to the electrical grid, when they are submitted to voltage sags due to the occurrence of faults in the electrical network. The recommended procedure in these cases is to maintaining the wind generator connected to the electrical network during and after the...
This paper investigates component minimized topology of single-phase to three-phase AC/DC/AC pulse width modulated (PWM) converter. It consists of half-bridge rectifier and two-leg (B4) inverter and is designed for low-power induction machine (IM) drive application. Effect of voltage imbalance between split capacitor bank is discussed and improved control algorithm is proposed to minimize imbalance...
A simple type A three-phase voltage sag generator with programmable is proposed for testing equipment, small or medium-power application, such as adjustable-speed drives (ASDs), contactors, relays, programmable logic-controller (PLC), and personal computers (PCs), etc. The generating system consists of a 1-kVA synchronous generator, a phase-control ac-dc converter, a mechanical prime-mover. Additional...
Crowbar-based control is one of the main low voltage ride through (LVRT) control methods for doubly-fed induction generator (DFIG), but converter is still at risk of being damaged by over-current at rotor side after crowbar exits during fault recovering period. For the issue, a model for fault process analysis based on equivalent dynamic model of DFIG is established. The mechanism of phase angle jumping...
The present paper addresses the control of doubly fed induction generators under unbalanced voltage sags considering the converter limits. A control strategy is proposed by choosing certain current reference values in the positive and negative sequences so that the torque and the DC voltage are kept stable during such unbalanced sags considering the converter limits.
The paper presents detailed simulation based analysis and investigation on grid code compliance of a new configuration of a 2 MW doubly fed induction generator. The converters of DFIG are connected and controlled to function like a unified power quality conditioner (UPQC). One of the converters is connected in series with the stator terminals and acts to maintain the stator voltage at a predetermined...
This paper proposes a new direct power control (DPC) strategy and a novel crowbar protection technique for the doubly fed induction generator (DFIG) used in the wind power generation systems. The main difficulty for a DFIG to ride through severe unbalanced grid voltage dips is the large transient currents induced in the rotor windings, which may damage the ac excitation converter. The proposed DPC...
This paper presents a Z-source ac-ac converter system and control for general-purpose motor drives. The Z-source ac-ac converter system employs a unique LC network to suppress the over-current and surge voltage due to the shoot-through or the open-circuit of the two switches. By controlling the duty cycle, the Z-source can provide buck-boost function, produce greater or less voltage than the line...
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