International Journ Internat ISSN No: 245 @ IJTSRD | Available Online @ www A Review Shaikh M P Department of Electrical Engineer ABSTRACT This paper is a review of an innovative t a new concept of transformer-less unifie controller (UPFC). The Transformer-l based on two cascade multilevel inve which reduce the complexity of the construction of the conventional UPF two back-to-back inverters which complexity and bulkiness which transformers which are complication fo attaining high power rating with re waveforms. The proposed controller w cost and space as compared to the UPFC. A multilevel configuration tech used to reduce the total harmonic con increases the overall efficiency of the sy INTRODUCTION The control of an AC power system i involved because power flow is a fu transmission line impedance, the mag sending and receiving end voltages, a angle between these voltages. In recent years, demand for electri continued to grow hence to achieve gre flexibility and better utilization of e systems the concept of flexible AC systems or FACTS is been introduced technology is a collection of Controlle be applied individually or in coordinatio to control one or more of the interr parameters. The most versatile FACT can be used to achieve power flow Unified power flow controllers (UPFCs) nal of Trend in Scientific Research and De tional Open Access Journal | www.ijtsr 56 - 6470 | Volume - 2 | Issue – 6 | Sep w.ijtsrd.com | Volume – 2 | Issue – 6 | Sep-Oct on Transformer - Less UPFC Mohammed Tauseef 1 , S. M. Kulkarni 2 PG Scholar 1 , Associate Professor 2 ring, PES College of Engineering, Aurangabad, M technique with ed power flow less UPFC is erters (CMIs), e circuit. The FC consists of h results in involves the or isolation & equired output will reduce the e conventional hnique will be ntent and thus ystem. in real time is unction of the gnitude of the and the phase ic power has eater operating existing power C transmission d. The FACTS ers, which can on with others related system TS device that control is the ). Fig. 1:- The Conven The Unified Power Flow Con was proposed by Gyugyi in devised for the real-time compensation of ac transmiss multifunctional flexibility req the problems facing the power The UPFC is able to cont selectively, all the parameters the transmission line (i.e., v phase angle), and this unique c the adjective "unified" in independently control both power flow in the line. It prop load capability of existing tran There are several advantage UPFC, but even though requirement of bulky zigzag t the inverters to transmission UPFC bulky and slow respo changes. To overcome conventional UPFC, recently, less UPFC based on Cascade (CMIs) has been proposed. evelopment (IJTSRD) rd.com p – Oct 2018 2018 Page: 940 Maharashtra, India ntional UPFC ntroller (UPFC) concept 1991. The UPFC was control and dynamic sion systems, providing quired to solve many of r delivery industry. trol, simultaneously or affecting power flow in voltage, impedance, and capability is signified by its name. It can also the real and reactive portionally increases the nsmission lines. es of the conventional it suffers from the transformers to interface lines, which makes the onding to dynamic load such drawbacks of , a modular transformer- ed Multi-level inverters
Transcript
International Journal of Trend in
International Open Access Journal
ISSN No: 2456
@ IJTSRD | Available Online @ www.ijtsrd.com
A Review Shaikh Mohammed Tauseef
PG ScholarDepartment of Electrical Engineering
ABSTRACT This paper is a review of an innovative technique with a new concept of transformer-less unified power flow controller (UPFC). The Transformer-less UPFC is based on two cascade multilevel inverters (CMIs), which reduce the complexity of the circuit. The construction of the conventional UPFC consists of two back-to-back inverters which results in complexity and bulkiness which involves the transformers which are complication for isolation & attaining high power rating with required output waveforms. The proposed controller will reduce the cost and space as compared to the conventional UPFC. A multilevel configuration technique will be used to reduce the total harmonic content and thus increases the overall efficiency of the system. INTRODUCTION The control of an AC power system in real time is involved because power flow is a function of the transmission line impedance, the magnitude of the sending and receiving end voltages, and the phase angle between these voltages. In recent years, demand for electric powercontinued to grow hence to achieve greaterflexibility and better utilization of existingsystems the concept of flexible AC transmission systems or FACTS is been introduced.technology is a collection of Controllers, which can be applied individually or in coordination with others to control one or more of the interrelated system parameters. The most versatile FACTS device that can be used to achieve power flow control is the Unified power flow controllers (UPFCs).
International Journal of Trend in Scientific Research and Development (IJTSRD)
International Open Access Journal | www.ijtsrd.com
Shaikh Mohammed Tauseef1, S. M. Kulkarni 2 PG Scholar1, Associate Professor2
Electrical Engineering, PES College of Engineering, Aurangabad, Maharashtra
This paper is a review of an innovative technique with less unified power flow
less UPFC is based on two cascade multilevel inverters (CMIs), which reduce the complexity of the circuit. The
nstruction of the conventional UPFC consists of back inverters which results in
complexity and bulkiness which involves the transformers which are complication for isolation & attaining high power rating with required output
osed controller will reduce the cost and space as compared to the conventional UPFC. A multilevel configuration technique will be used to reduce the total harmonic content and thus increases the overall efficiency of the system.
The control of an AC power system in real time is involved because power flow is a function of the
magnitude of the sending and receiving end voltages, and the phase
electric power has achieve greater operating
flexibility and better utilization of existing power systems the concept of flexible AC transmission
FACTS is been introduced. The FACTS llers, which can
coordination with others to control one or more of the interrelated system
The most versatile FACTS device that used to achieve power flow control is the
s).
Fig. 1:- The Conventional UPFC
The Unified Power Flow Controller (UPFC) concept was proposed by Gyugyi in 1991.devised for the real-time control and dynamic compensation of ac transmission systems, providing multifunctional flexibility required to solve many ofthe problems facing the power delivery industry. The UPFC is able to control, simultaneously or selectively, all the parameters affecting power flow in the transmission line (i.e., voltage, impedance,phase angle), and this unique capability is signified by the adjective "unified" in its name. independently control both the real and reactivepower flow in the line. It proportionally increases the load capability of existing transmission lines. There are several advantages of theUPFC, but even though it suffers from the requirement of bulky zigzag transformers to interface the inverters to transmission UPFC bulky and slow responding to dynamic load changes. To overcome such draconventional UPFC, recently, a modular transformerless UPFC based on Cascaded Multi(CMIs) has been proposed.
Research and Development (IJTSRD)
www.ijtsrd.com
6 | Sep – Oct 2018
Oct 2018 Page: 940
Maharashtra, India
The Conventional UPFC
The Unified Power Flow Controller (UPFC) concept was proposed by Gyugyi in 1991. The UPFC was
time control and dynamic transmission systems, providing
required to solve many of the problems facing the power delivery industry.
he UPFC is able to control, simultaneously or all the parameters affecting power flow in
the transmission line (i.e., voltage, impedance, and nique capability is signified by
in its name. It can also independently control both the real and reactive
It proportionally increases the transmission lines.
advantages of the conventional UPFC, but even though it suffers from the
zigzag transformers to interface lines, which makes the
UPFC bulky and slow responding to dynamic load To overcome such drawbacks of
recently, a modular transformer-on Cascaded Multi-level inverters
International Journal of Trend in Scientific Research and Development (IJTSRD) ISSN: 2456
@ IJTSRD | Available Online @ www.ijtsrd.com
Theory of Transformer – Less UPFC The proposed transformer-less UPFC configuration is shown in Fig. 2(a), which consists of two CMIs: series CMI and shunt CMI.
Fig. 2(a):-
The series CMI is directly connected in series with the transmission line and the shunt CMI is directly connected in parallel to the line but after the series CMI. Each CMI, as shown in Fig. 2(b) and (c), is composed of a number of cascade H-bridge bridge modules.
Fig. 2(b):-
Fig. 2(c):-
Here are the unique features of the new 1. Unlike the conventional back-to-
coupling, there is no transformer needed CMI-based UPFC; hence, the new UPFC can achieve low cost, light weight, small size, high efficiency, high reliability, and fast dynamic response;
2. The shunt inverter is connected after the series inverter, which is distinctively different from the traditional UPFC. Each CMI has its own dc capacitor to support dc voltage;
3. There is no active power exchange between the two CMIs and all dc capacitors are floating;
4. The new UPFC uses modular CMIs and their inherent redundancy provides greater flexibility tosystem design and higher reliability.
International Journal of Trend in Scientific Research and Development (IJTSRD) ISSN: 2456
The series CMI is directly connected in series with the transmission line and the shunt CMI is directly connected in parallel to the line but after the series
Fig. 2(b) and (c), is bridge or half-
the new configuration: -back dc link
coupling, there is no transformer needed in the based UPFC; hence, the new UPFC can
achieve low cost, light weight, small size, high efficiency, high reliability, and fast dynamic
The shunt inverter is connected after the series inverter, which is distinctively different from the
aditional UPFC. Each CMI has its own dc
There is no active power exchange between the two CMIs and all dc capacitors are floating; The new UPFC uses modular CMIs and their inherent redundancy provides greater flexibility to system design and higher reliability.
Advantages � Improves voltage profile for the duration of the
transient conditions in the power transmission systems.
� Low THD of output voltage� Low switching loss. � High efficiency. � Independent active and reactive
control over the transmission line Applications � AC transmission, distribution
electrical energy. � Power grid. � Transmitting electrical energy over long distances� Electricity supply industry� Used to couple stages of
devices such as microphones Conclusion In this paper, review of a new based on a novel configuration of two CMIs was proposed. It has been discussedcan achieve the same controllability as the traditional UPFC. However, the traditional UPFC consisting of two back to-back inverters requiresand zigzag transformers. The new UPFCtwo CMIs offers several traditional UPFC, such as completely transformerand highly modular structure,efficiency, high reliability, low cost, and fast dynamic response. The new transformertherefore, very well suited for fastpower flow control of wind and solar powertransmission. References 1. N. G. Hingorani and L. Gyugyi, UnderStanding
FACTS: concept and technology of flexible AC transmission systems. New York: IEEE Press2000.
2. L. Gyugyi, “Unified powerfor flexible AC transmission systems,” IEE Proc. C Gener., Transmiss. Distrib., vol. 139,pp. 323331, 1992.
3. H. Akagi, S. Inoue, and T. Yoshii, “Control and performance ofa transformerless cascade PWM STATCOM with star configuration,” IEEE Trans. Ind. Appl., vol. 43, no. 4, pp. 10412007.
International Journal of Trend in Scientific Research and Development (IJTSRD) ISSN: 2456-6470
Oct 2018 Page: 941
Improves voltage profile for the duration of the transient conditions in the power transmission
Low THD of output voltage.
Independent active and reactive power flow control over the transmission line.
distribution, utilization of
Transmitting electrical energy over long distances. Electricity supply industry.
amplifiers and to match microphones and record players
a new transformer-less UPFC novel configuration of two CMIs was
discussed that the new UPFC same controllability as the traditional
nal UPFC consisting of requires bulky isolation
zag transformers. The new UPFC consisting of two CMIs offers several advantages over the traditional UPFC, such as completely transformer-less
highly modular structure, light weight, high reliability, low cost, and fast dynamic
transformer-less UPFC is, therefore, very well suited for fast and distributed power flow control of wind and solar power
N. G. Hingorani and L. Gyugyi, UnderStanding FACTS: concept and technology of flexible AC
New York: IEEE Press,
L. Gyugyi, “Unified power-flow control concept for flexible AC transmission systems,” IEE Proc.
Transmiss. Distrib., vol. 139,pp. 323–
H. Akagi, S. Inoue, and T. Yoshii, “Control and performance ofa transformerless cascade PWM STATCOM with star configuration,” IEEE Trans. Ind. Appl., vol. 43, no. 4, pp. 1041–1049,Jul./Aug.
