Volume 03 Issue 12-2023
14
American Journal Of Applied Science And Technology
(ISSN
–
2771-2745)
VOLUME
03
ISSUE
12
Pages:
14-18
SJIF
I
MPACT
FACTOR
(2021:
5.
705
)
(2022:
5.
705
)
(2023:
7.063
)
OCLC
–
1121105677
Publisher:
Oscar Publishing Services
Servi
ABSTRACT
This article provides an overview of the current state of reactive power compensation technologies. The principles of
operation, design characteristics and examples of the use of VAR compensators on thyristors and self-commutated
converters are given. VAR static generators are used to improve voltage regulation, stability and power factor in AC
transmission and distribution systems. Also described are examples obtained from the respective annexes describing
the use of reactive power compensators implemented using the new static VAR technologies.
KEYWORDS
VAR, principles of operation, self-commutated.
INTRODUCTION
VAR compensation is defined as reactive power
management to improve the performance of AC
systems. The VAR compensation concept covers a
wide and diverse range of problems for both the
system and consumers, especially related to the quality
of electricity that can be mitigated or solved by
adequate reactive power management [1]. In general,
the problem of reactive power compensation is
considered from two sides: load compensation and
voltage support. In load compensation, the goals are
to increase the value of the system's power factor,
balance the actual power consumed from an
alternating current source, compensate for voltage
regulation and eliminate the harmonic components of
the current created by large and fluctuating nonlinear
industrial loads [2], [3]. Voltage support is usually
required to reduce voltage fluctuations at a given end
of the transmission line. Reactive power compensation
in transmission systems also improves the stability of
the AC system by increasing the maximum active
power that can be transmitted.
Research Article
REACTIVE POWER COMPENSATION TECHNOLOGIES
Submission Date:
December 04, 2023,
Accepted Date:
December 09, 2023,
Published Date:
December 14, 2023
Crossref doi:
https://doi.org/10.37547/ajast/Volume03Issue12-04
M.A. Alibekova
Andijan machine - building institute, Uzbekistan
Journal
Website:
https://theusajournals.
com/index.php/ajast
Copyright:
Original
content from this work
may be used under the
terms of the creative
commons
attributes
4.0 licence.
Volume 03 Issue 12-2023
15
American Journal Of Applied Science And Technology
(ISSN
–
2771-2745)
VOLUME
03
ISSUE
12
Pages:
14-18
SJIF
I
MPACT
FACTOR
(2021:
5.
705
)
(2022:
5.
705
)
(2023:
7.063
)
OCLC
–
1121105677
Publisher:
Oscar Publishing Services
Servi
Fig. 1. Principles of shunt compensation in a radial AC system.
a) Without reactive compensation.
b) Shunt compensation with a current source.
Sequential and shunt VAR compensation are used to
change the natural electrical characteristics of AC
systems. Sequential compensation changes the
parameters of the transmission or distribution system,
while shunt compensation changes the equivalent load
impedance [1], [7]. In both cases, the reactive power
flowing through the system can be effectively
controlled, improving the performance of the entire AC
system. Traditionally, rotating synchronous capacitors
and fixed or mechanically switchable capacitors or
inductors have been used to compensate for reactive
power. However, in recent years, static VAR
compensators have been developed, which use
thyristor-switched capacitors and thyristor-controlled
reactors to provide or absorb the required reactive
power [7], [8], [9]. In addition, the use of self-switching
PWM converters with an appropriate control circuit
allows the implementation of static compensators
capable of generating or absorbing reactive current
components with a time reaction faster than the main
cycle of the power grid [10], [11], [12]. Selection of the
structure model and boundary conditions. In a linear
scheme, reactive power is defined as a component of
an alternating current of instantaneous power with a
frequency equal to 100/120 Hz in a system with a
frequency of 50 or 60 Hz. The reactive power
generated by an alternating current source is stored in
a capacitor or reactor for a quarter of a cycle, and in the
next quarter of the cycle it is sent back to the power
source. In other words, the reactive power fluctuates
between an alternating current source and a capacitor
or reactor, as well as between them, with a frequency
equal to twice the nominal value (50 or 60 Hz). For this
reason, it can be compensated with VAR generators,
avoiding its circulation between the load (inductive or
capacitive) and the source, and thus improving voltage
stability in the power system. Reactive power
Volume 03 Issue 12-2023
16
American Journal Of Applied Science And Technology
(ISSN
–
2771-2745)
VOLUME
03
ISSUE
12
Pages:
14-18
SJIF
I
MPACT
FACTOR
(2021:
5.
705
)
(2022:
5.
705
)
(2023:
7.063
)
OCLC
–
1121105677
Publisher:
Oscar Publishing Services
Servi
compensation can be implemented using VAR
generators connected in parallel or in series.
As a rule, VAR generators are classified depending on
the technology used in their implementation and the
way they are connected to the power system (shunt or
serial). Rotating and static generators were commonly
used to compensate for reactive power. In the last
decade, a large number of different static VAR
generators using power electronic technologies have
been proposed and developed [7].
There are two approaches to the implementation of
VAR compensators based on power electronics: one
uses thyristor-switched capacitors and reactors with
branch-switching transformers, and the second uses
static converters with automatic switching.
Fig. 2. Serial capacitor compensator and the corresponding protection system.
Fig. 3. Configuration of a capacitor with thyristor switching.
A brief description of the most commonly used bypass
and sequential compensators is provided below.
Regardless of the type of source or system
configuration,
various
requirements
must
be
considered for the successful operation of VAR
generators. Some of these requirements are simplicity,
manageability, dynamics, cost, reliability, and harmonic
distortion. The following sections describe the various
solutions used to generate VAR, as well as the
associated operating principles and compensation
characteristics.
The capacitor can be switched with a minimum of
transients if the thyristor is switched on at a time when
the capacitor voltage and the mains voltage have the
same value. Static compensators of the TSC type have
Volume 03 Issue 12-2023
17
American Journal Of Applied Science And Technology
(ISSN
–
2771-2745)
VOLUME
03
ISSUE
12
Pages:
14-18
SJIF
I
MPACT
FACTOR
(2021:
5.
705
)
(2022:
5.
705
)
(2023:
7.063
)
OCLC
–
1121105677
Publisher:
Oscar Publishing Services
Servi
the following properties: stepwise control, an average
delay of half a cycle (maximum one cycle) and the
absence of harmonic generation, since the transient
component of the current can be effectively
attenuated [6], [7].
Fig. 4. Experimental compensating phase current of a thyristor-diode switching capacitor.
The advantages of this topology are that many
compensation levels can be implemented with
multiple branches, allowing continuous change
without
distortion. In addition, the topology is simpler and
more economical compared to thyristor-switched
capacitors. The main disadvantage is that it has a time
delay of one full cycle compared to the half-cycle of the
TSC.
Conclusions. An overview of the technological
development of VAR generators and compensators is
presented. Based on the principles of VAR
compensation, classical solutions using phase-
controlled semiconductors were considered.
The introduction of self-switching topologies based on
IGBT and IGCT semiconductors has significantly
improved the characteristics of VAR compensators:
they have faster dynamic behavior and can control a
large number of variables. The introduction of new
self-switching topologies at even higher voltage levels
will enhance the impact of VAR compensation in future
applications. Some relevant examples of projects have
been described where it can be seen that modern VAR
compensators improve the operation of power
systems, helping to improve the reliability and quality
of electricity supplied to consumers. These examples
show that VAR compensators will be used on a much
larger scale in the future, as network performance and
reliability will become even more important factors.
Better manageability of the energy system will allow
utilities to reduce investments in the transmission lines
themselves. The combination of modern management
with real-time information and information technology
will bring them closer to their physical limits. In
addition, the development of faster and more
powerful semiconductor valves will expand the
possibilities of using VAR generators to higher limits.
REFERENCES
Volume 03 Issue 12-2023
18
American Journal Of Applied Science And Technology
(ISSN
–
2771-2745)
VOLUME
03
ISSUE
12
Pages:
14-18
SJIF
I
MPACT
FACTOR
(2021:
5.
705
)
(2022:
5.
705
)
(2023:
7.063
)
OCLC
–
1121105677
Publisher:
Oscar Publishing Services
Servi
1.
T. J. Miller, “Reactive power Control in Electric
Systems,” John Willey & Sons, 1982.
2.
E. Wanner, R. Mathys, M. Hausler, “Compensation
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ystems for Industry,” Brown Boveri Review, vol.
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A. Hammad, B. Roes
le, “New Roles for Static VAR
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Nickolai Grudinin and Ilya Roytelman, “Heading Off
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Carson W. Taylor, “Improving Grid Behavior”, IEEE
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7.
Canadian
Electrical
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Compensators for Reactive Power Control,”
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Power Generation and Control by
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Applications, vol. IA-15, nº 5, pp. 521-532, Sept./Oct.
1979.
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L. Gyugyi, R. Otto, T. Putman, “Principles and
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