Power Invariance Transformation in Power Systems

2000 ◽  
Vol 37 (2) ◽  
pp. 180-189
Author(s):  
J. Heydeman ◽  
W. W. Schongs
Keyword(s):  
Power Systems ◽  
Single Phase ◽  
Positive Sequence ◽  
Equivalent Representation ◽  
Symmetrical Components ◽  
Three Phase ◽  
Sequence Components ◽  
Invariance Transformation

Many textbooks describe a balanced three-phase circuit by a single-phase equivalent representation. Confusion may arise amongst students regarding per-unit values of line-to-line voltages and phase voltages and, therefore, about the magnitudes of currents and powers. This paper proposes that students must first be taught symmetrical components based on power invariance transformation. A balanced three-phase circuit is to be described only in terms of positive sequence components. In the authors' experience, students understand this approach better and make fewer errors in per-unit calculation than when they use the single-phase equivalent representation.

Three Phase Power Flow Incorporating Static Var Compensator

2014 ◽  
Vol 573 ◽  
pp. 747-756 ◽  
Author(s):  
B. Karthik ◽  
Jerald Praveen Arokkia ◽  
S. Sreejith ◽  
S. Rangarajan Shriram
Keyword(s):  
Power Systems ◽  
Transmission Lines ◽  
Power Flow ◽  
Single Phase ◽  
Load Condition ◽  
Test System ◽  
Load Flow ◽  
Static Var Compensator ◽  
Three Phase ◽  
Sequence Components

Application of Flexible AC Transmission Systems (FACTS) devices in a power system is a promising and more efficient way for the transfer and control of bulk amount of power. One of the problems encountered in power-systems operation is the generation of unbalanced voltages and currents in the presence of long transmission lines with few or no transpositions. This includes possible unbalances arising in source and load conditions, or indeed any items of plant such as shunt and series reactors. To improve or investigate these unbalance effects in any detail, a 3-phase load-flow solution that allows representation of all possible unbalances as they exist in the power-systems network without making any assumptions is essential. This paper deals with the three phase power flow incorporating Static Var Compensator (SVC). Here SVC is modeled using variable reactance modeling technique and incorporated into the single phase and three phase load flow. Newton Raphson power flow algorithm is adopted here. The performance of SVC to control the power flow and regulating voltage in the network is discussed. The performance analysis is carried out for 4 case studies namely single phase power flow, single phase power flow with SVC, three phase power flow and three phase power flow with SVC. The change in power flow and losses due to the unbalanced load condition in the three phases in illustrated. The studies are carried out in a standard 5 bus test system. Keywords: Three Phase Power flow, Static Var Compensator, Unbalanced system, Negative sequence components, Zero sequence components.

Study of the Two-Phase Operation Mechanism of Three-Phase Motors Based on LC Phase Shifting Method

2015 ◽  
Vol 741 ◽  
pp. 714-719
Author(s):  
Zai Ping Zheng ◽  
Yu Ping Huang ◽  
Yue Zhong ◽  
Hong Xing Wu
Keyword(s):  
Power Supply ◽  
Single Phase ◽  
Simulation Software ◽  
Phase Shifting ◽  
Practical Significance ◽  
Positive Sequence ◽  
Two Phase ◽  
Symmetrical Components ◽  
Three Phase ◽  
Phase Shifting Method

In the absence of three-phase power supply, it has certain practical significance to connect the three-phase induction motor to the single-phase power supply for single phase operation. This paper analyzes the asymmetric circuit system of the motor by the method of symmetrical components-Lc phase shifting, disassembles the voltage and current of the three-phase motor stator winding into three groups of symmetrical components: positive sequence, negative sequence and zero sequence. We derivate and analysis the LC phase shifting method to simulate and validate the Lc phase shifting method theory, deduce the formula for calculating of optimum external capacitance and inductance, simulate and calculate all kinds of single phase operation method, finally we use the simulation software to simulate and validate three-phase induction motors single phase operation.

Chaotic Modeling of Ferroresonance with Single-Phase Open in a Three-Phase System and Its Fractional-Order Control

2021 ◽  
Vol 31 (08) ◽  
pp. 2150118
Author(s):  
Ali̇ Durdu ◽  
Yilmaz Uyaroğlu
Keyword(s):  
Power Systems ◽  
Fractional Order ◽  
Chaotic System ◽  
Single Phase ◽  
Duffing Oscillator ◽  
Phase System ◽  
Fractional Order Control ◽  
Practical Applications ◽  
Mathematical Expressions ◽  
Three Phase

In this study, a chaos-theoretic method is proposed to model the case of ferroresonance that can occur under nominal conditions in power systems, and the factors that determine the types of ferroresonance to occur are examined. In the ferroresonance chaotic system modeled in Matlab environment, the length of the transmission line and the breaker capacities in the circuit are fixed and its relationship with the transformer efficiency is investigated. In the proposed chaotic modeling, considering the situations that may occur in practical applications, the ferroresonance situations that occur when the single-phase remains open in the three-phase system are examined. In the study, ferroresonance, which occurs when one phase is open in a three-phase system, is analyzed by considering the situations that may happen during practical implementations. The similarity between the mathematical expressions obtained from the systems that create ferroresonance and Duffing oscillator is evaluated. In the chaotic system, fundamental ferroresonance, subharmonic ferroresonance, and chaotic ferroresonance situations are created depending on the transformer loss. Additionally, ferroresonance that occurs when the chaotic system is of fractional-order is analyzed, and it is observed that results of ferroresonance with different fractional-order values are not different. The results show that transformer loss is a significant element to determine the type of ferroresonance in power transformers. Also, when the chaotic system is operated in the fractional-order setting, the ferroresonance cases that occur are re-examined, and it is observed that the system can exit from the chaotic situation and prevent the formation of ferroresonance when fractional-order control is applied. According to the results, the fractional-order method can be used to control ferroresonance.

Sensitivity of Induction Motor under Symmetrical Voltage Sags and Interruption

2014 ◽  
Vol 875-877 ◽  
pp. 1923-1928 ◽  
Author(s):  
Surya Hardi ◽  
Ismail Daut ◽  
Ismail Rohana ◽  
Muhd Hafizi
Keyword(s):  
Power Systems ◽  
Distribution Systems ◽  
Single Phase ◽  
Induction Motors ◽  
Short Circuit ◽  
Inrush Current ◽  
Voltage Sags ◽  
Three Phase ◽  
Nominal Voltage ◽  
Transmission And Distribution

Voltage sags and interruption are one of most important of power quality problems. They can influence performance of equipment such as induction motors. They are generally caused by short circuit faults in transmission and distribution systems which propagate in entire of power systems. When their appear at a motor terminal, its effects are the speed and the torque will decrease to a level lower than values of the normal and even the motor become stall if magnitude of the voltage sags and duration exceed certain limit. The voltage can return to nominal voltage after end of the voltage sag and interruption. The motor will experience re-acceleration to normal condition is accompanied by large inrush current. A study on induction motors was carried out to confirm these effects. Single-phase and three-phase of small induction motors were used for investigating the effects caused by symmetrical voltage sags and interruption through experimental and simulation.

scholarly journals Fault Ride-Through Capability Enhancement for Microinverter Applications

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Sajad Arab Ansari ◽  
Amir Reza Mizani ◽  
Siamak Ashouri ◽  
Javad Shokrollahi Moghani
Keyword(s):  
Power Systems ◽  
Single Phase ◽  
Low Voltage ◽  
Pv Systems ◽  
Low Voltage Ride Through ◽  
Fault Ride Through ◽  
Three Phase ◽  
Future Challenges ◽  
Wind Power Systems ◽  
Conduction Mode

Due to the fast growth of single-phase grid-connected photovoltaic (PV) systems, the existing grid codes are expected to be modified to guarantee the availability, quality, and reliability of the electrical system. Therefore, the future single-phase PV systems should become smarter and support low voltage ride-through (LVRT) capability, which are required for three-phase wind power systems. In this paper, the operation principle of a flyback inverter in a low-voltage ride-through operation is demonstrated in order to map future challenges. The steady state performance of the flyback inverter under voltage rise and drop conditions at boundary conduction mode (BCM) and discontinues conduction mode (DCM) is studied theoretically. The simulation results of the flyback inverter for various grid faults are presented to verify the theoretical analyses. The results indicate the fact that the flyback inverter at BCM condition can provide LVRT capability for photovoltaic microinverter applications in distributed generation (DG) systems, even though it does not need any auxiliary control branches and any limitations in components design.

scholarly journals Hybrid power quality conditioner for three-phase four-wire power systems

2020 ◽  
Vol 178 ◽  
pp. 01009
Author(s):  
Maxim Chernyshov ◽  
Valery Dovgun ◽  
Sergei Temerbaev ◽  
Zumeyra Shakurova
Keyword(s):  
Power Systems ◽  
Power Quality ◽  
Single Phase ◽  
Hybrid Power ◽  
Three Phase ◽  
Zero Sequence ◽  
Network Operation ◽  
Power Quality Conditioner ◽  
Wire System ◽  
Nonlinear Nature

The article considers a hybrid power quality conditioner (HQPC) for 3-phase 4-wire systems with a distributed modular structure. Some conditioner modules provide compensation for the component currents and voltages that form the negative and zero sequence systems. The open structure of the HQPC, consisting of independent modules, allows compensating for distortions of currents and voltages of the 3-phase network caused by the nonlinear nature and asymmetry of single-phase loads. The compensation characteristics of the proposed conditioner were researched using a model developed in the MatLab environment. The simulation showed that the proposed conditioner can ensure normalization of power quality in 3-phase 4-wire system at various modes of network operation.

Analysis of the Influence of Magnetic Field on Voltage Error of Three-Phase Three-Element Combined Transformer

2014 ◽  
Vol 1070-1072 ◽  
pp. 1105-1110 ◽  
Author(s):  
Gang Liu ◽  
Bo Jiang ◽  
Lin Dong Ren ◽  
Guo Ci Lei ◽  
Fu Zhou Zhang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Power Systems ◽  
High Voltage ◽  
Single Phase ◽  
True Error ◽  
Verification Method ◽  
Error Characteristics ◽  
Three Phase ◽  
Current Error

Power systems as 10kV, 35kV and etc have a lot of high-voltage three-phase three-element combined transformer. At present, all of the combined transformers are verified according to single-phase verification method, but the results can’t reflect the true error characteristics of combined transformer. So, it is suggested to adopt three-phase verification method to verify combined transformer. However, when combined transformer is verified according to three-phase verification method, it has not been clear yet that what influence magnetic field generated by current has on voltage error. In this paper, through voltage error test on combined transformer with three-phase verification method at different current, it is discovered that magnetic field has a larger influence on voltage error in the presence of a magnetic field, with the increase of voltage, the influence of magnetic field on voltage error decreased gradually from larger values. The use of three-phase verification method and appropriate modification of current error limits are recommended when combined transformer is verified.

Implementation of Single Phase Locked Loop Based on FPGA and its Application in SVC

2014 ◽  
Vol 986-987 ◽  
pp. 1826-1832
Author(s):  
Yu Jie Pei ◽  
Yun Shan Zhang ◽  
Jian Guo Xu ◽  
Jing Long Mu ◽  
Lei Zhang ◽  
...  
Keyword(s):  
Power Systems ◽  
Adaptive Sampling ◽  
Single Phase ◽  
Response Speed ◽  
Phase Locked Loop ◽  
Sampling System ◽  
Three Phase ◽  
Voltage Phase ◽  
Real Time Digital Simulator ◽  
Phase Phase

Whereas three-phase phase locked loop could not get accurate phase position under three-phase unbalanced condition of the power grid, the design of single phase locked loop is implemented in the principle of single phase locked loop, based on FPGA technology. the paper explains design difficulties of single phase locked loop in detail, puts forward adaptive sampling scheme using single phase locked loop under variable frequency, increases accuracy of SVC sampling system. And tests response speed of phase locked loop via Real Time Digital Simulator for Power Systems (RTDS), through final verification in Fushun Lishizhai SVC Project, the design could meet system requirement for voltage phase accuracy.

scholarly journals Induction Motor Stator Interturn Short Circuit Fault Detection in Accordance with Line Current Sequence Components Using Artificial Neural Network

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Gayatridevi Rajamany ◽  
Sekar Srinivasan ◽  
Krishnan Rajamany ◽  
Ramesh K. Natarajan
Keyword(s):  
Neural Network ◽  
Fault Detection ◽  
Induction Motor ◽  
Short Circuit ◽  
Positive Sequence ◽  
Negative Sequence ◽  
Three Phase ◽  
Sequence Components ◽  
Negative Sequence Current ◽  
Short Circuit Fault

The intention of fault detection is to detect the fault at the beginning stage and shut off the machine immediately to avoid motor failure due to the large fault current. In this work, an online fault diagnosis of stator interturn fault of a three-phase induction motor based on the concept of symmetrical components is presented. A mathematical model of an induction motor with turn fault is developed to interpret machine performance under fault. A Simulink model of a three-phase induction motor with stator interturn fault is created for extraction of sequence components of current and voltage. The negative sequence current can provide a decisive and rapid monitoring technique to detect stator interturn short circuit fault of the induction motor. The per unit change in negative sequence current with positive sequence current is the main fault indicator which is imported to neural network architecture. The output of the feedforward backpropagation neural network classifies the short circuit fault level of stator winding.

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