27-11-2012, 05:59 PM
Fuzzy Logic Control of Doubly Fed Induction Generator Wind Turbine
Fuzzy Logic Control of Doubly Fed Induction Generator Wind Turbine.pdf (Size: 447.93 KB / Downloads: 269)
INTRODUCTION
Wind energy is one of the extra ordinary sources
of renewable energy due to its clean character and
free availability. Moreover, because of reducing the
cost and improving techniques, the growth of wind
energy in Distributed Generation (DG) units has
developed rapidly
In terms of wind power generation technology,
because of numerous technical benefits (higher energy
yield, reducing power fluctuations and improving var
supply) the modern MW-size wind turbines always use
variable speed operation which is achieved by a
converter system [1]. These converters are typically
associated with individual generators and they
contribute significantly to the costs of wind turbines.
Between variable speed wind turbine generators,
doubly fed induction generators (DFIGs) and
permanent magnet synchronous generators (PMSGs)
with primary converters, are emerging as the preferred
technologies [2].
STUDY SYSTEM
represents single line diagram of studied
system in this paper. Configurations and parameters of
the system are extracted from [5] with a little change in
local load values. Micro-grid consists of three main
feeders, two DG units and five local loads. Main grid is
represented by a three phase 69 kV voltage source with
1000MVA short circuit capacity and X/R ratio of 22.2.
Micro-grid is normally connected to the main grid
through a 15MVA upward transformer.
L1 to L4 are local linear loads and L5 is a
nonlinear load which is presented thorough a three
phase diode rectifier that feeds a resistance as a
resistive load
Connection point of main and micro-grid which is
called Point of Common Coupling (PCC) is fed through
a 1.5 Mvar fixed shunt capacitor bank.
DG1 is a 5MVA synchronous generator with its
exciter and governor system. It can be considered as a
diesel or gas turbine generator unit. It’s connected
directly to bus 1 and thorough a 2.06Km radial line to
the PCC. Its parameters are described in Table 1.
DFIG MODEL
As illustrated in Fig. 3, DFIG system is a wound
rotor induction generator with slip ring, with stator
directly connected to the grid and with rotor interfaced
through a back to back partial scale power converter.
The converter consists of two conventional voltage
source converters that are called Rotor Side Converter
(RSC) and Grid Side Converter (GSC) and a common
DC-link [3]. Consequently the DFIG can be regarded as
a traditional induction machine with a nonzero rotor
voltage.
FUZZY CONTROL
The control system is based on fuzzy logic. This
type of control, approaching the human reasoning that
makes use of the tolerance, uncertainty, imprecision
and fuzziness in the decision-making process, manages
to offer a very satisfactory performance, without the
need of a detailed mathematical model of the system,
RESULTS
For studying dynamic behavior of proposed system
based on fuzzy logic controller, some different
situations and events are considered. Based on different
fault locations and severity, the system has different
responses. In each condition, many different parameters
such as wind speed, voltage, active and reactive power
and etc are shown to prove the capability of the
proposed controller.
Single line to ground fault near DG1: In this part a
single line to ground short circuit fault with duration of
0.1s is applied near the synchronous generator (DG1).
The fault is applied at 5s and is removed at 5.1s.