Aysen Basa Arsoy

Voltage profile and short circuit analysis in distribution systems with DG

The use of distributed generation (DG) within distribution systems has increased for the last two decades due to institutional requirements and technical advances. This study presents the impact of DG in different types of distribution systems in terms of voltage profile and short circuit analysis. Test systems representing three types of distribution systems (radial, loop and network) are simulated using the simulation tool of Powerfactory-DigSilent while changing the location and penetration level of DG in the system. The results are useful in better understanding the system impact of DG.

Assessment of integral based fault detection methods for power system relaying

In this paper, cumulative sum and moving sum based fault detection algorithms are presented for a power system relaying application. Simplicity and accuracy are the two attractive features for both of the methods. The methods are tested in a simple test system. When compared with conventional methods, it is found that integral based fault detection methods are more effective than the conventional ones. CUSUM method is not affected in the presence of noise, system frequency deviation and the other uncertainties. The moving sum method has a small detector output for the same conditions. But since the index value is high for this method, it can be accepted as negligible.

Impact of Coupling Breakers in a Power Plant Fault Analysis

Over the last decades, the private sector power plants are integrated into the power system with growing number and size. Since these power plants are large, their impacts on the grid are strong as well. The steady state and transient analyses required for plant connection to the grid, mostly play a role in the selection of the equipment and determination of the protection settings. Installation and commissioning of power plants based on accurate analyses are of great importance in raising the reliability of the system. The number of generating units in a power plant can be increased for capacity expansion. The coupling breakers (bus tie breakers) are used in plant substations configured in double bus scheme. Each generator are connected to the grid through these buses having the coupling breaker in a closed/opened position. This study investigates the impact of these breakers in terms of short circuit faults by using a real data obtained from the natural gas power plant connected to the 154 kV grid through overhead transmission line. Fault currents are computed based on IEC 60909 and compared for different status of coupling breakers.

Analysis of Reduced Order Model based on doubly-fed induction generators during different fault times

In this study, three phase fault analysis of wind turbines consist of Doubly-Fed şnduction Generators (DFIGs) has been examined. The dynamic analysis of DFIG has been conducted by Reduced Order Model (ROM). Three Phase fault has been made in 34.5 kV bus, happended in three bus power systems. The three phase fault time has been choosen as 0.02 second, 0.05 second and 0.1 seconds. 154 kV bus voltage, 34.5 kV bus voltage, DFIG output voltage, DFIG angular speed, DFIG electrical torque and DFIG d-q axes stator and rotor current variations of system in different fault times has been examined. According to the results, it has been seen that three phase fault is especially effective upon 34.5 kV bus voltage and DFIG output voltage in different fault times analysis.

A reliability study of medium voltage grid with private sector power plants

The number of private sector power plants connected to the national grid has been increasing recently. Those plants with various in sizes may have a positive contribution to the grid. Numerous calculations are carried out in equipment selection and protection setting to integrate the power plant to the grid. Not only these calculations but also a proper operation of a plant are so important in improving system reliability. This is mostly considered as the base case for the worst scenario. In this paper, a reliability evaluation study of private sector power plants connected to an MV grid is given in terms of plant and grid reliability and reserve margin. Data taken from a real power plant operation is used for this study. Obtained results are compared to show the improvement in grid reliability.