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Generators used in multi-machine power systems are very affected by transient situations such as malfunctions and line breaks. In transient situations, the system becomes unstable, and oscillations increase. In particular, order modeling of synchronous generators effectively eliminates transient stability situations. To analyze this in the best way, a small signal stability analysis is performed. This study was carried out in the MATLAB-based Power Systems Analysis Program (PSAT), using the 2nd-order and 5th-order models of the synchronous generator for small signal stability analysis in a 3-machine 9-bus power system. While the 2nd-order model is used as the traditional model in synchronous generators, the 5th-order model has been developed as a dynamic order model. Especially in the 5th-order model, it was developed based on a subtemporal model for better damping of the system. In the comparisons made in both order models, the real and imaginary values and participation factors are shown in figures, while the eigenvalues, damping percentage, frequency, dominant values, and operating modes are presented in tables. By using both order models in the synchronous generator, the number of eigenvalues of the system was determined. The results obtained showed that the 5th-order model gave better results in small signal stability analysis. [ABSTRACT FROM AUTHOR]

Due to various operating conditions of power systems, bus voltages and load parameter values decrease. This causes the system to go into instability. Static Synchronous Compensator (STATCOM) is widely used to eliminate instability situations. Fuel cells can be used from energy storage systems to increase the efficiency of STATCOM in power systems. In this study, STATCOM and fuel cell are used together for steady and transient voltage stability in a 6-bus power system. In the voltage stability system, the relationship between the bus voltage-maximum load parameter in the steady-state operation is examined, while in the transient state study, the relationship between the bus voltage-maximum load parameter for the transient stability that occurs in the case of breaker opening-closing on the line in the system. In addition, the effects of the fuel cell at different power values are examined in detail. As a result of the study, it has been seen that the use of STATCOM and fuel cell together gives effective results in terms of voltage stability in continuous and transient situations. [ABSTRACT FROM AUTHOR]

Power systems are vulnerable to transients such as line contingency and short circuit. Various models are used to eliminate instability problems as soon as possible. In particular, the Power System Stabilizer (PSS), which is one of the synchronous generator controller models, is widely used. In this study, the transient stability of IEEE's 14 bus system was investigated in detail by using different PSS models together with secondary voltage control. In addition, it is considered to use the Automatic Voltage Regulator (AVR) together with the most suitable model for the coordinated operation of different PSS models and secondary voltage control. The pilot bus has been determined for the use of secondary voltage control consisting of central area control and cluster control, and it is aimed to provide coordination control of AVR and PSS models in the synchronous generator. This study was analyzed using the Power Systems Analysis Program (PSAT). By using different PSS models, synchronous generator angular speed changes, bus voltage profiles, and synchronous generator active-reactive power changes were investigated. As a result of the study, it was seen that the PSS 2 model provided system stability and reduced oscillations in a short time compared to other models. [ABSTRACT FROM AUTHOR]

Today, Flexible AC Transmission Systems (FACTS) devices provide local reactive power support in load centers and keep bus voltages within safe operating limits. In particular, the single use of parallel FACTS devices may not improve the safe operating conditions of the system depending on the load conditions. Therefore, avoiding parallel FACTS devices' high costs is crucial and determining their optimal places in the system. For this, Static Var Compensator (SVC), one of the parallel FACTS devices, is used. This study investigated the effects of multiple uses of SVC on different load buses on the maximum load parameter of the multi-machine system in a 3-machine 9-bus power system. Moreover, bus-voltage profiles and their changes in active-reactive power are studied in detail. In this study, three analysis methods were used. These are the no SVC, the single use of SVC, and the multiple uses of SVC. The Power Systems Analysis Program (PSAT) was preferred for this simulation study. As a result of the study, using multiple SVCs increases the maximum loading parameter value and improves the bus-voltage profiles and active-reactive power changes compared to others. [ABSTRACT FROM AUTHOR]

Stability analyzes are examined with the help of simulation programs in the continuous, economical and reliable operation of multi-machine power systems. The most common stability analysis in power systems is small signal stability. In this study, small signal stability analysis was investigated with different generator controller models in a 4-machine 2-field test system. Power System Stabilizer (PSS), Automatic Voltage Regulator (AVR) and Turbine Governor (TG) are used as different generator controller models. The simulation study was carried out in the Power Systems Analysis Program (PSAT). Comparisons were made between the situation where there are no controllers in the synchronous generator and the situations with PSS, AVR and TG models. Comparisons are given in figures and tables. In this study, it was observed that the use of PSS, AVR and TG models in a synchronous generator stabilized the system in a short time, the oscillations in the parameters were reduced and the system gave more effective results in terms of small signal stability. [ABSTRACT FROM AUTHOR]

Copyright of Duzce University Journal of Science & Technology is the property of Duzce University Journal of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The damping of small frequency oscillations is an important issue in terms of power system stability. These oscillations are damped by the power system stabilizer (PSS). In recent years, power electronics based Flexible AC Transmission System (FACTS) devices have been used efficiently in power system stability studies. In this study, different PSS models, the most advanced model of FACTS devices Unified Power Flow Control (UPFC) and Power Oscillation Damping (POD) were used to provide coordination controller. In addition to PSS models used in synchronous generators, Automatic Voltage Regulator (AVR) and Turbine Governor (TG) models were also used. Small signal stability analysis was carried out in a 2-field, 4-machine system. Power Systems Analysis Program (PSAT) was used for the simulation study. As a result of the study, angular velocity, voltage, active and reactive power comparisons were made in the use of different PSS models with UPFC-POD, and small signal stability analyzes were interpreted. [ABSTRACT FROM AUTHOR]

Copyright of Duzce University Journal of Science & Technology is the property of Duzce University Journal of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Duzce University Journal of Science & Technology is the property of Duzce University Journal of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

One of the chief methods used to overcome voltage dip problems in doubly fed induction generator (DFIG)-based wind turbines is low voltage ride through (LVRT) capability. In order to solve such voltage dip problems during symmetrical and asymmetrical grid faults, this study presents a novel enhanced dynamic modeling approach for LVRT in DFIG. Positive and negative sequence models, along with natural and forcing flux models were used to enhance the proposed LVRT capability strategy for a DFIG. In addition, electro-motor-force (EMF) was applied for the enhancement of the stator and rotor circuit model. The novel statorrotor dynamic modeling was also used in boosting the transient stability operation against three phase and two phase faults. When the proposed dynamic modeling was applied, the system was stabilized within a short amount of time and the oscillations ceased. [ABSTRACT FROM AUTHOR]

There are many conditions for determining the voltage-maximum loading relationship in multi-bus power systems. One of these is the line contingency in power systems. In this study, Effects on voltage stability of the line contingency occurred different points in IEEE 14 buses power system. Line contingency is considered as disabled for a certain period of time of the breakers situated in line. The effects of line contingency at 19 points on the voltage-loading parameter were observed. Besides, In this study, the effects of bus voltage profile changes were investigated. As a result of this study, it has been seen that line contingency decrease the system loading parameter value and operating limits in different transmission lines. In particular, the line contingency between the state transmission line 2-3, which brought the loading parameter value and the operating limits to the critical value. [ABSTRACT FROM AUTHOR]

The effects of nonlinear load models on the system are an important issue in terms of power quality. In this study, the effect of nonlinear load models in the grid-connected Doubly Fed Induction Generator (DFIG) based wind turbine was investigated. Exponential, constant impedance, constant current, constant active power (ZIP) and induction motor are used as nonlinear load model. Composite load modeling is consist of exponential-ZIP-induction motor. Composite load modeling is turn on and turns off system within different times. Analysis and stability analysis of the composite load modeling were examined. This simulation study was carried out in MATLAB / SIMULINK environment. 34.5 kV bus voltage, DFIG terminal voltage, DFIG electrical torque, DFIG d-q axis stator current variations and DFIG d-q axis rotor current variations in composite load model analysis are examined. As a result of, it has been seen that composite load modeling which is activated as short time is effective on the power system. [ABSTRACT FROM AUTHOR]

Copyright of Mugla Journal of Science & Technology is the property of Mugla Journal of Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)