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The paper presents a brief overview of the standard IEC60255–121 and focusses on the challenges and advantages of using transient simulation for assessing protective relays. The importance of the use of statistical methods to investigate the behaviour of algorithms is discussed. Finally a new solution for performing these kinds of tests is introduced.
A new method for detection occurrences of CT saturation is presented in this paper. The presented algorithm applies only first order derivatives of signals which is possible it has been designed in a new innovative methodology in which phase current signals are considered as coordinates of a 3D vector. The proposed algorithm is compared with standard one applying secondary current signal combined...
Worldwide analysis of recent wide area cascading failures has shown that very often they were mainly caused by the maloperation of the third zone of a distance protection relay. The load encroachment and power swing phenomena are the two dire problems to solve when dealing with the third zone of distance protection. The vast number of blackouts could have been avoided or the consequences lowered if...
There were many accidents of large-scale wind turbines disconnecting from power grid in 2011. Single-phase-to-ground fault cannot be correctly detected. Single-phase-to-ground evolved to phase-to-phase fault. Phase-to-phase fault was isolated slowly, which led to low voltage. And wind turbines without enough low voltage ride-through capacity disconnected from the grid. After some wind turbines disconnected...
Over the years, different methods have been used in order to avoid problems with load encroachment, and each method presents its own set of advantages and disadvantages. Regardless of the method used, each relay will have a maximum "loadability limit" that will cause the relay to operate under high load conditions. Therefore, it is important for the relay engineer to understand and take...
This paper deals with line protection challenges experienced in system having substantial wind generation penetration. Two types of WTGU: Doubly Fed (DFIG) and Squirrel Cage (SCIG) Induction Generators are simulated and connected to grid with single circuit transmission line. The paper summarizes analytical investigations carried out on the impedance seen by distance relays by varying fault resistances...
The concentration of electric power at system buses adds to both the need for high-speed tripping in case of faults and the need to avoid false tripping in case of external faults. This combined need for both superior dependability and security has led to many enhancements and system modifications in bus protection. Bus configurations with multiple zones are particularly difficult to provide with...
This paper presents a novel protective concept for EHV Three-terminal transmission line, teed circuit. The proposed protective relaying techniques use the fourth sequential overlapping derivative, SOD, concept at all line terminals. The SOD signals represent the transient components initiated due to fault occurrence. Such signals are free of both dc and fundamental components. Two protective relaying...
Distance relays used for transmission line protection can mal-operate on power swing. This paper presents protection schemes for out of step detection based on synchronized phasor measurement. Voltages and currents at both the ends of a transmission line are used to derive the parameters required for designing these schemes. The proposed schemes can distinguish stable and unstable power swing and...
At present, gas protection and current differential protection are generally used as the main protection for traction transformer in China high-speed railway. Overcurrent protection with busbar low-voltage start-up is used as the backup protection installed at HV side and LV side of transformer. This paper introduces the principle of overcurrent protection with busbar low-voltage start-up, and then...
This paper addresses three aspects of testing relay protection systems using a real time simulator: (1) simplify the setup by using low level analog signals to the relay; (2) use a ‘threading’ process when a hybrid setup (commercial relays and simulated relay models) is chosen; (3) test substation protection system together with control and communication systems.
The presence of supplementary controllers for thyristor controlled series compensators (TCSC), to damp the Inter-area power system oscillations makes the resultant transmission line (T.L), reactance varying during the damping process. This variation causes an undesirable effect on the distance relay DR, as its setting depends on the physical impedance of the T.L. In this paper, a novel algorithm is...
This paper presents a network-based simulator for protective relaying algorithms. The simulator is based on the client-server paradigm. The simulator which consists of server-side relaying algorithm modules and the user interface provides the network-based environment to simulate a variety of protective relaying algorithms. It is developed by using open-source development tools and model-based design...
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