Electronics & Communication Technologies - Digital Controller for Wind Electric Generators

Introduction

Indian research centre set up in 1974 is offering technology for digital controller for wind electric generators. It is engaged in control and instrumentation, networking technology, ASIC design, audio/video technology and hardware software realisation, power electronics, underwater electronics. The centre is interested in offering the above technology to business enterprises.

Digital generators for wind electric turbines are controller to get unity power factor at the grid and to track the maximum power point by variable speed operation. AC-DC-AC conversion is employed. Digital controller based on digital signal processor is used to implement the control functions.

Salient features:

• The digital controller for wind electric generator (WEG) is developed for variable speed operation of the induction generator and power export to grid at unity power factor.
  
• Variable speed operation of the induction generator
  
• Improvement in turbine utilisation
  
• Extraction of maximum available power at various wind conditions
  
• Unity power factor operation at the grid side
  
• Absence of separate power factor correcting capacitors

A wind turbine operates with its maximum efficiency at a particular tip speed ratio. Therefore to achieve maximum power extraction at all wind speeds, the tip speed ratio is maintained constantly by varying the rotor speed with reference to the wind speed.

The system is made of two bi-directional power stages, one at the generator side to control the power generation and the other at the grid side to control the active/reactive components of power feed to the grid. The power controllers are three phase inverters using insulated gate bipolar transistors (IGBT). The two stages are coupled through a DC link working at a voltage level of 650V. The grid side controller synchronises system output with the grid and enables the power flow from the DC bus to the grid at unity power factor for all wind speeds. The machine side controller tracks the maximum power factor for all wind speeds. The machine side controller tracks the maximum power applying square low for turbines. The machine is supplied with a variable frequency variable voltage supply according to the wind conditions. The operating region is tailored to match with the optimum turbine power co-efficient at all wind speeds so that maximum power can be derived.

The real time controller synthesizes parameters like grid voltage, grid frequency, line currents, DC voltage etc. in a sample time of 50us to generate suitable switching pattern for both the converters. The digital controller hardware has been built based on two Texas TMS320C5xDSPs along with an 80188 micro-controller. The DSP part is used for operations involving large amount of computations and signal processing, and the micro-controller part of interfacing and supervisory operations. The triggering signals are coupled to the power.

Stages through fibre optic cables to achieve necessary isolation and EMC compatibility. A computer interface is provided for data logging. The signals from the existing controller are communicated with the digital controller using an interface unit. The status of the system (voltage, frequency, power, wind speed, etc.) is displayed in the display unit. Settings like voltage limits, frequency limit etc. can be made with the help of push button switches in the display and control unit.

Environmental aspects: Green technology in the sense that power from wind is optionally extracted.

Areas of Application

Wind Electric Turbines

Advantages

Power factor unity
Stability of the grid improved
Power generation increased

Stage of Development

Prototype, Patented

Inputs Required

Raw materials: Electrical and electronic components
Manpower: Total 6 including 2 technicians, 2 skilled, 2 unskilled

Economic Data

Know-how fee and training fee : Negotiable

For further information please contact :

Technology Bureau for Small Enterprises
APCTT Building, Qutub Institutional Area
P.O. Box – 4575
New Delhi – 110016, India

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