A small-scale standalone wind energy conversion system featuring SCIG, CSI and a novel storage integration scheme

Abstract

Small-scale standalone wind turbines provide a very attractive renewable energy source for off-grid remote communities. Taking advantage of variable-speed turbine technology, which requires a partial-or full-scale power converter, and through integrating an energy storage system, smooth and fast power flow control, maximum power point tracking, and a highquality power is ensured.Due to high reliability and efficiency, permanent magnet synchronous generator seems to be the dominating generator type in gearless wind turbines, employed for off-grid applications.However, wind turbines using geared squirrel-cage induction generator (SCIG) are still widely accepted due to their robustness, simplicity, light weight and low cost. Permanent magnet induction generator, a relatively new induction-based machine, has recently been recognized in the wind energy market as an alternative for permanent magnet synchronous generator. A thorough comparative study, among these three generator types, is conducted in this research in order to enable selection of the most appropriate generator for off-grid wind energy conversion system (WECS), subject to a set of given conditions. The system based on geared SCIG has been shown to be the most appropriate scheme for a small-scale standalone WECS, supplying a remote area.Different topologies of power electronic converters, employed in WECSs, are overviewed.Among the converters considered, current source converter is identified to have a great potential for off-grid wind turbines.Three current-source inverter-based topologies, validated in the literature for on-grid WECS, are compared for off-grid WECS application. Feasibility study and performance evaluation are conducted through analysis and simulation. Among all, the topology composed of three-phase diode bridge rectifier, DC/DC buck converter, and pulse-width-modulated current-source inverter (PWM-CSI) is identified as a simple and low-cost configuration, offering satisfactory performance for a low-power off-grid WECS.A small-scale standalone wind energy conversion system featuring SCIG, CSI and a novel energy storage integration scheme is proposed and a systematic approach for the dc-link inductor design is presented. iv In developing the overall dynamic model of the proposed wind turbine system, detailed models of the system components are derived. A reduced-order generic load model, that is suitable for both balanced and unbalanced load conditions, is developed and combined with the system components in order to enable steady-state and transient simulations of the overall system. A linear small-signal model of the system is developed around three operating points to investigate stability, controllability, and observability of the system. The eigenvalue analysis of the small-signal model shows that the open-loop system is locally stable around operating points 1 and 3, but not 2. Gramian matrices of the linearized system show that the system is completely controllable at the three operating points and completely observable at...

Rotor Fault Detection of Wind Turbine Squirrel Cage Induction Generator Using Teager–kaiser Energy Operator

“…For the special situation of the studied stator current data in this paper, the sampling frequency of 10 kHz has demonstrated to be very low for the estimation of the frequency bandwidths of the data that were most sensitive to damage, as shown in Figures 2 and 3. Through the Hilbert transform study that has been previously presented in [1], [17], [18], [16], [20], [34], [35], this transform is fully not local, and all the samples are required to be calculated with Hilbert transform at each point. The calculation of the Hilbert transform of a 15 defects presented on the rotor, and also appropriate for real-time implementations.…”

“…On the other side, it has been applied in several applications such as in communications studies to the representation of the instantaneous frequency of transient signals. In energy supply analysis, the energy operator is used for the detection of the three-phase power supply oscillations; in the electrical engineering field, especially for bearings failures diagnostics [10], [11], [20]- [33].…”

“…is the number of sideband jumps. In this work, more attention is given to the first two current components presented in (20) with k = 1. Where the amplitudes of the remaining frequencies decay too fast and are practically more difficult to be detected.…”

A review on technology maturity of small scale energy storage technologies

“…The micro-CAES is a technology for electrical and thermal energy storage, it could improve energy efficiency and optimizing operating efficiency while safeguarding the environment. It can be used as an alternative to the battery for industrial applications, such as UPS and back-up power systems [2,15,19].…”

“…These reviews have been normally done with regard to systems at medium or large scale, but very a few of them specify technology choices for small scale energy systems. Also, other papers tend to present some certain types of energy storage for particular applications at small scale level, such as [14][15][16][17]. Thus, there is a need for a systemic review of energy storage technologies for small scale energy systems.…”