Download The thyristors switched reactor based SVC to load voltage

IMPROVEMENT OF REACTIVE POWER BY
TSR
Hetal P. Patel1, Assist. S.L.Kailya2
1,3
Department of Electrical Engineering, Gujarat Technological University
Rajkot, India
Address
[email protected]
[email protected]
Abstract— In long EHV transmission lines at lightly
loaded condition the receiving loaded condition, the
receiving end voltage goes beyond the sending end
voltage due to leading capacitive charging. Moreover
the problem of power factor deviation and reactive
power disturbance also occurs. In such condition TSR
provides effective and promising against these
problems. TSR consumes lagging reactive current and
reduces the leading capacitive current and reduces the
leading capacitive current of the transmission line. In
this paper simulation of TSR is carried out and ability
to generate lagging re-active current at different firing
angle is compared.
Keywords— Flexible AC Transmission systems,
Thyristor, Switched Reactors, SVC, MATLAB
I. INTRODUCTION
Flexible AC Transmission Systems (FACTS)
Controllers can be used for solving these problems.
Different types of FACTS controllers are described.
Flexible AC Transmission system (FACTS) is a new
integrated concept based on power electronic
switching converters to enhance the system
utilization and power transfer capacity as well as
stability, security and reliability, power quality of AC
system interconnections. Flexible AC Trans-mission
Systems (FACTS) by incorporating power electronic
controllers.[2]
FACTS in AC system can be used compensation,
control of phase angle, voltage control, damping of
system oscillations and control of power flow in
transmission line. Power factor is the phase shift
between the phase shift the voltage and line voltage
and line current waveforms. Power factor is
necessary for working of electrical equipments.
The thyristors switched reactor based SVC to load
voltage has been examined in the three phase system
at statics load and dynamic load conditions. Power
factor is a small amount of reactive power is
necessary for working of electrical equipments.
Power factors can be increased by (1) synchronous
motor or synchronous generators (2) capacitor banks
(3) synchronous condensers (4) static VAR
compensators (5) static synchronous compensator.
SVC based two types: 1. TSR
2. TCR
Basically fc-tcr (fixed capacitor-thyristors controlled
reactor) in this device the Q value of the capacitor is
constant as the capacitor is a fixed one and we can
get the required reactive power by varying the Q of
inductor using thyristors.
QREQ = QCAP - QTCR for TSC (THYRISTOR
SWITCHED CAPACITOR) here we can vary the
thyrisors in only two ways ie. Full or partial
conduction. But in tcr we can vary the thyristors
angle from 0-180° usually a combination of tcr, tsc
and tsr makes a svc[3].
II. PRINCIPLES OF TSR
TSR is a shunt connected devices that can absorb
reactive power.TSR having following properties: its
operating principle simple, delay of one half a cycle
and no generating of harmonics.fig 1. The TSR
equivalent circuit is show.TSR consists of two
thyristors in anti-parallel and to be switched.
BLOCK DIAGRAM:
Fig.1 Main structure of TSR
In 3-phase application the basic TSR elements are
connected in delta. The control in TSR two
techniques are: 1. either fully on, 2. either fully off.
3-phase system long transmission line one load is
connected. Indicator is also connected to the
transmission line[4]. The transmission line CT and
PT is also is also calculated to impedance
calculation.TSR is connected and two anti parallel
switches connected. The TSR firing angle calculation
using zero inductive current controller.TSR based
SVC equivalent circuit
Fig 2. TSR-Based SVC Configuration
The SVC is acquired to reactive and capacitive
operation interval. Thyristor in structure of TSR are
fired at the positive/negative peak of the source
voltage or at the zero crossing of the line current. The
harmonic generation has been prevented in the
energy system [5].
Fig 3. Basic Block Diagram
III. DESIGN AND IMPLEMENTATION
The TSR is a special case of a TCR in which the
variable firing angle control option is not exercised.
In the device is operated in two states only: either
fully on or fully off. If the thyristor valves are fired
exactly at the voltage peaks corresponding to AC 90
for the forward thyristor valve T1 and AC 270 the
reverse thyristor valve T2,as depicted ,full
conduction results[7].
The TSR will remain in a blocked off state, and no
current can flow. The TSR ensures a very rapid
availability of rated inductive power to the system.
when a large magnitude of controlled reactive power
Q, is required, A part of Q is usually assigned to a
small TSR of rating say Q/2; [3] the rest is realized
by means of a TSR also of a reduced rating Q/2.This
arrangement results in substantially losses and
harmonic content as compared to a single TCR of
rating Q.
α = 120°
α = 140°
Fig 4. Single phase TSR based svc
configuration
α = 90°
Firing angle is increase voltage is increase and
current is decrease. Waveform of α = 90,105,120,140
are desigen.
III. CONCLUSION
In this report the simulation of TSR is carried out open loop
configuration more of flexibility also proposed scheme if
tested used different firing angle value. In next stage the
simulation of TSR closed loop of configuration can be
carried in closed loop configuration with more preside
control.
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