Top PDF Transient Stability Performance Analysis of Power System Using Facts Devices

Transient Stability Performance Analysis of Power System Using  Facts Devices

Transient Stability Performance Analysis of Power System Using Facts Devices

IV. Modeling of STATCOM controller: The controller for STATCOM is shown in fig1. The voltage and current are referred from area2 generator represented with Vabc and Iabc. With these parameters, real and reactive powers are calculated. These power system is controlled independently by using transfer functions to derive direct and quadrature axis voltages. These direct axis voltage can control real power and quadrature axis will control the reactive power flow from STATCOM. The two phase voltages are converted into three phase (dq -abc) voltages and this reference voltage is fed to PWM converter to generate pulses to STATCOM. This controls the direction of current flow from STATCOM to system or vice-versa based on difference in voltage magnitude at reference point at STATCOM DC voltage. If at reference point, voltage is higher, current will flow to STATCOM and when at reference point are low, current flows from STATCOM. The voltage at reference point can be high due to Ferranti effect or sudden load throw off, lightning and voltage may decrease due to heavy loading or due to faults. The aim of STATCOM is maintain constant voltage magnitude at reference point, minimise inter-area oscillations and to enhance stability and reliability. The results are compared without STATCOM and with STATCOM for the circuit shown figure2 and figure 3. A three phase to ground fault occurs at 0.1 seconds and clears naturally at 0.2 seconds with fault resistance of 1mJ respectively between phases and ground. Three winding transformers are used; primary winding is connected to area1, secondary winding is connected to area2 and tertiary winding is connected to STATCOM1.
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Implementation of Line Stability Index for Contingency Analysis and Screening in Power Systems

Implementation of Line Stability Index for Contingency Analysis and Screening in Power Systems

collapse point. The index can either reveal the critical bus of a power system or the stability of each line connected between two buses in an interconnected network or evaluate the voltage stability margins of a system. Results: Flexible Alternating Current Transmission Systems (FACTS) devices have been proposed as an effective solution for controlling power flow and regulating bus voltage in electrical power systems, resulting in an increased transfer capability, low system losses and improved stability. However to what extent the performance of FACTS devices can be brought out highly depends upon the location and the parameters of these devices. Unified Power Flow Controller (UPFC) is the most promising FACTS device for power flow control. Conclusion/Recommendations: The performance of this index is presented and the effectiveness of the analyzed methods is demonstrated through simulation studies in IEEE 14 bus reliability test systems.
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Computer Aided Transient Stability Analysis

Computer Aided Transient Stability Analysis

The flow chart shown represents the main program which calls different subroutines; such a structure which permits the removal and addition of system components. The transient stability program operates when a fault occurs on the system. If the system is unstable, it gives hint to the load flow program to redistribute the power, i.e., increase the electrical power for generating units in steps chosen. The program will start by reading the data file, converting the transformers to their π-equivalent, forming the Y- matrix and starting the iterative solving algorithm using fast decoupled method. When the program reaches to a
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Design and Modelling of Fuzzy and Model Predictive Controllers for STATCOM to enhance Transient Stability of Power System

Design and Modelling of Fuzzy and Model Predictive Controllers for STATCOM to enhance Transient Stability of Power System

In this paper the STATCOM control scheme for the Single-Machine Infinite Bus (SMIB) system to improve transient stability is simulated using MATLAB/Simulink in power systems block set. The Simulation models of PI, FLC and MPC were developed. The Performance of different controllers is analyzed for a load disturbance. When comparing the results, performance of PI controller with STATCOM, gives high peak overshoot and more settling time. Performance of fuzzy logic controller with STATCOM, gives low peak overshoot and quick settling time when comparing the results with PI controller. The Response of Model Predictive controller with STATCOM, the values of peak overshoot and settling time is found to be lower than the results of FLC with STATCOM. Thus MPC provide better control in transient stability improvement of the simulated power system.
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FACTS Devices Using Neuro Fuzzy Controller in Stabilization of Grid Connected Wind Generator.

FACTS Devices Using Neuro Fuzzy Controller in Stabilization of Grid Connected Wind Generator.

Wind power is one of the renewable energy sources. It has various advantages like, cost competitiveness, environmentally clean and safeness. Large wind farms have stability problems when they are integrated to the power system. A thorough analysis is required to identify the stability problems and to develop measures to improve it. Mostly used wind generator is a fixed speed induction generator, which requires reactive power to maintain air gap flux. Reactive power equipments are used to enable recovery of large wind farms from severe system disturbances. In this paper shunt and series FACTS devices, Static Synchronous Compensator (STATCOM) and Static Synchronous Series Compensator are used for the purpose of stabilizing grid connected wind generator against the grid-side disturbances. The essential feature of the FACTS devices is their ability to absorb or inject the reactive power. Since stability is a non linear process so system performance can be improved by using nonlinear controllers. Neurofuzzy controller (NFC) is a non linear controller. NFC has faster response than conventional PI controllers.
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Fuzzy Logic Controller for Static Synchronous Series Compensator with Energy Storage System for Transient Stability Analysis

Fuzzy Logic Controller for Static Synchronous Series Compensator with Energy Storage System for Transient Stability Analysis

Interfacing SMES with VSI: A superconducting magnetic energy storage containing electronic converters rapidly injects and/or absorbs the real and/or reactive power or dynamically controls the power flow in an ac system. Since the dc current in the magnet does not change rapidly, the power input or output of the magnet is changed by controlling the voltage across the magnet with a suitable electronics interface. An electronic interface known as chopper is needed between the energy source and the VSI. For VSI the energy source compensates the capacitor charge through the electronic interface and maintains the required capacitor voltage. Two-quadrant n-phase DC- DC converter as shown in Fig. 6 is adopted as interface. Here ‘n’ is related to the maximum current driven by the superconducting device. The DC-DC chopper solves the problems of the high power rating requirements imposed by the superconducting coil to the SSSC. It allows to reduce the ratings of the overall power devices by regulating the current flowing from the superconducting coil to the inverter of the SSSC (Padma and Lakshmipathi, 2010). It is composed of many shunt connected diode-thyristor legs that permit the driving of the high current ratings stored in the superconducting coil. In this study two-quadrant three phase chopper is taken.
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Voltage Stability Enhancement and Efficiency Improvement of Nigerian Transmission System Using Unified Power Flow Controller

Voltage Stability Enhancement and Efficiency Improvement of Nigerian Transmission System Using Unified Power Flow Controller

ABSTRACT: Consistent increase in the demand for electrical energy often leads to heavy loading of transmission lines. One of the consequences of this is that such transmission systems are subjected to imbalance in the reactive power and hence voltage instability and reduction in real power of the system. Conventional methods of enhancing voltage stability and improving efficiency have proven to be slow and difficult to control. A new approach, however, is the use of Flexible AC Transmission System (FACTS) controllers. This paper applied Unified Power Flow Controller (UPFC), a member of this class of devices to Nigeria’s 330kV transmission system using MATLAB. Obtained results showed an improvement in the voltage magnitude of bus 9 and bus 13 from 0.9896 and 0.9765 to 1.02 and 1.0199 respectively. Also, the active power loss was reduced by 2.53% from 85.177MW to 83.025MW when UPFC was applied. Incorporation of UPFC improved the system’s voltage stability and reduced active power losses. The UPFC could therefore be deployed to minimize prolonged and frequent voltage instability in transmission networks and enhance system efficiency.
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Transient Stability Analysis of a Three-machine Nine Bus Power System Network

Transient Stability Analysis of a Three-machine Nine Bus Power System Network

Abstract- Transient stability analysis plays an important role for planning, designing and upgrading an existing electrical power system network. In this paper, transient stability analysis is carried out by considering a three-phase fault at the busbars 7 and 4 with the effect of various fault-clearing times. The simulation is carried out using CYME 5.02 power system software with fast decoupled method. It is found that at fault clearing times of 0.05s, 0.1s, and 0.15s, the generators (G2, G3) under test are stable with respect to the simulation time. Whereas, at fault clearing times of 0.2s and 0.3s, these generators are found to be unstable for both faulted busbars 7 and 4. These simulation results are then compared with the proposed model results and are found to be in good agreement. In addition, it has been demonstrated that the transient stability of a system can be improved using control devices.
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Performance Assessment of Brazilian Power Transmission and Distribution Segments using Data Envelopment Analysis

Performance Assessment of Brazilian Power Transmission and Distribution Segments using Data Envelopment Analysis

Regarding Table 6, ELETROPAULO achieved the best result of overall efficiency, followed by COELBA, CEMIG-D, CPFL-PAULISTA, CELPE and ELEKTRO. In addition, ELETROPAULO was considered the corporation with greatest stability, since it achieved the lowest STDV value among all companies. On the other hand, CELG-D was considered the company with worst stability and CELESC-D the one with worst performance, since its values for STDV and AVG are the highest and lowest, respectively. Moreover, comparing both scenarios, distribution and transmission of electrical energy, it is possible to infer that companies within distribution system presented higher stability compared to those within transmission system, since values of STVD are overall lower. Overall efficiency can also be assessed by averaging all efficiency values for each window. As shown in Table 7, distribution system achieved higher values of overall efficiency regarding all windows. Those findings suggests that in general corporations within distribution system have a better level of management regarding their operating costs than those within transmission system, verifying the results regarding cost reductions carried out previously.
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Index Terms  Performance Analysis, Commercial Power

Index Terms  Performance Analysis, Commercial Power

The increased requirements on supervision, control, and performance in modern power systems make power quality monitoring a required practice for utilities. Some electronic devices, such as microprocessors, micro-controllers, sensitive computerized equipment and telecommunications equipment, etc., use ground as the reference for all their internal operations and connect throughout the plant. This makes them susceptible to ground differences and to power quality problems. Power disturbances compromise product quality, increase downtime, and reduce customer satisfaction. By knowing the amount of harmonics, transient impulses and noise distortion in the system, it is possible to take appropriate actions to reduce the harmful effects [1], [2]. Consequently, there is an ever increasing need for power quality monitoring systems. This performance analysis is of particular interest because it has been found that different PQ
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Induction motor voltage flicker analysis and its mitigation measures using custom power devices: A case study

Induction motor voltage flicker analysis and its mitigation measures using custom power devices: A case study

induction motor loads of municipal integrated water pumping system. The impact of additional connection of induction motors to the same system has been analyzed. Measurements are done at the point of common coupling (PCC) to identify background short time flicker levels and the contribution of the already operating induction motors. The paper also analyses and compares different voltage flicker mitigation methodologies to assess their performance with change in line impedance phase angle for this particular application. Here, Matlab-7.01/PSB is used to present the detailed results of all voltage flickers compensating methodologies and to assess the impact of line impedance X/R sweep on effectiveness of custom power devices. It is observed that distribution static synchronous compensator (DSTATCOM) is found more effective for compensating voltage flicker generated by the induction motor load.
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TRANSIENT STABILITY ANALYSIS OF PERMANENT MAGNET SYNCHRONOUS GENERATOR WITH TWO LEVEL CONVERTER INVERTER

TRANSIENT STABILITY ANALYSIS OF PERMANENT MAGNET SYNCHRONOUS GENERATOR WITH TWO LEVEL CONVERTER INVERTER

Due to the fluctuating nature of wind the output of the variable speed PMSG varies in amplitude and frequency which is not suitable for use. In the model system used in this paper a PMSG wind generator is connected to the power system network through a fully controlled power converter. The power convertor consists of generator side AC/DC convertor, DC link capacitor and grid side DC/AC invertor. The generator side convertor controls the electromagnetic torque and therefore the extracted power while the grid side convertor controls both the DC link voltage and the power factor. The simulation analysis is performed by using MATLAB, Simpower system. By suitably controlling the power converters of PMSG in proper way, the transient stability of VSWT-PMSG can be enhanced.
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Simulation and Comparison of Various FACTS Devices in Power System

Simulation and Comparison of Various FACTS Devices in Power System

Abstract - The Power electronic based FACTS devices can be added to power transmission and distribution systems at strategic locations to improve system performance. This paper deals with the simulation of various FACTS controllers using simulation program with Integrated circuits Emphasis (PSPICE) .The FACTS controllers will control series impedance, shunt impedance, current, voltage and phase angle. In this paper, simple circuit model of Thyristor Controlled Reactor, Thyristor Controlled voltage regulator and UPFC systems were simulated. The simulation results coincide with the theoretical results.
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Transient Stability Assessment of a Power System Using Probabilistic Neural Network

Transient Stability Assessment of a Power System Using Probabilistic Neural Network

The use of PNN has been proposed for transient stability assessment of electrical power system by means of classifying the system into either stable or unstable states for several three phase faults applied to the system. Time domain simulations were first carried out to generate training data for the PNN and to determine transient stability state of a power system by visualizing the generator relative rotor angles. Principle component analysis is also applied to extract the useful input features to the PNN. The PNN is then compared with the MLPNN so as to evaluate its effectiveness in transient stability assessment. Results show that the PNN gives better performance than the MLPNN in terms of transient stability classification. Another advantage of PNN compared to MLPNN is that the training time is significantly faster. Thus, the PNN is a promising neural network technique for the transient stability assessment of power systems.
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Power System Stability Enhancement Using Unified Power Flow Controller

Power System Stability Enhancement Using Unified Power Flow Controller

Modern power system network is getting much more complicated and heavily loaded than ever before. The consequence of such is the risk of stability problem. Transient stability is one of the important aspects in power system (Zarate-Minano at al., 2010; Pizano-Matinez at al., 2009; Augusto at al., 2008). There are many advanced devices have been proposed during the last three decades to improve stability of power system such as High Voltage Direct Current (HVDC) system and Flexible AC Transmission System (FACTS) devices (Ahmad and Al-Husban, 2009; Moghadasi et al., 2008; Kumkratug, 2010).
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Simulation of Voltage Stability and Alleviation Through Knowledge Based System

Simulation of Voltage Stability and Alleviation Through Knowledge Based System

Abstract: Modern power systems are large sized and rapidly growing. They require constant attention to monitor their performance. Attention is also required to ensure that the voltage stability margin of the power system is above a desired level. In order to achieve the objective, this study proposes a knowledge-based system. It computes using simple Fast De-Coupled Load Flow (FDLF), the state of a power system. Thereafter, the power system is subjected to an additional load at a certain power factor. If the power system collapses, then additional capacitor that needs to be switched on is computed by an iterative procedure. This is done for different load levels and tabulated. Thereafter, in the actual usage, based upon the computed Table, given any load one may determine the level of compensation required to avert voltage collapse.
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The Mathematical Model of Power System with Thyristor Controlled Series Capacitor in Long Transmission Line

The Mathematical Model of Power System with Thyristor Controlled Series Capacitor in Long Transmission Line

It was found from the simulation results that the resistance of the line provides the improvement of the first swing but not for the second swing. It was found from this study that for practical long line, the resistance is very import parameters to determine the critical clearing time of the single machine infinite system whereas shunt capacitance would not affect on critical clearing time of single machine infinite bus system. It was also found in this study that the TCSC can enhance transient stability of power system.
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CHARACTERISTIC OF STEADY-STATE REGIME FOR ONE OF SCENARIOUS OF MOLDOVA RIGHT BANK POWER SYSTEM INTEGRATION TO ENTSO-E

CHARACTERISTIC OF STEADY-STATE REGIME FOR ONE OF SCENARIOUS OF MOLDOVA RIGHT BANK POWER SYSTEM INTEGRATION TO ENTSO-E

[6] Zaitev D., Golub I., Tirsu M., Calinin L.Comparative analysis of the options for the development of power system networks in the frame of scenarios which including joint of Moldova (only right bank) to ENTSO-E., INTERNATIONAL CONFERENCE “SIELMEN– 2013, Chisinau, Republic of Moldova

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The Mathematical Model and Simulation of Static Var Compensator in Medium Transmission Line

The Mathematical Model and Simulation of Static Var Compensator in Medium Transmission Line

Abstract: Problem statement: The Static Var Compensator (SVC) have been widely investigated its effect on transient stability of Single Machine Infinite Bus (SMIB) system. The exact medium transmission line model in power system consists of the series resistance series reactance and shunt capacitance. It is not easy task to obtain the mathematical model of the SVC with the exact medium transmission line model for investigating transient stability performance. Approach: This study applied the concept of the two-port network to simplify the mathematical model of the power system. The full capacity of the SVC on transient stability improvement of the SMIB with the medium transmission line was then investigated. The proposed method was tested on sample system and compared on various cases. Results: The first swing of rotor angle curve of the faulted system without resistance was obviously higher than that of with resistance whereas the second swing of the faulted system without resistance was slightly less than that of with resistance. The system with a SVC could improve transient stability of power system. Conclusion: The SVC and resistance of the line can improve first swing of rotor angle. The resistance of the line provides negative effect on second swing of rotor angle. The simulation results indicate that for practical medium line, the resistance is very import parameters for evaluating transient stability of power system.
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