Showing 4 results for Distance Relay
Y. Damchi, J. Sadeh, H. Rajabi Mashhadi,
Volume 11, Issue 2 (6-2015)
Abstract
The aim of the relay coordination is that protection systems detect and isolate the faulted part as fast and selective as possible. On the other hand, in order to reduce the fault clearing time, distance protection relays are usually equipped with pilot protection schemes. Such schemes can be considered in the distance and directional overcurrent relays (D&DOCRs) coordination to achieve faster protection systems, while the selectivity is maintained. Therefore, in this paper, a new formulation is presented for the relay coordination problem considering pilot protection. In the proposed formulation, the selectivity constraints for the primary distance and backup overcurrent relays are defined based on the fault at the end of the transmission lines, rather than those at the end of the first zone of the primary distance relay. To solve this nonlinear optimization problem, a combination of genetic algorithm (GA) and linear programming (LP) is used as a hybrid genetic algorithm (HGA). The proposed approach is tested on an 8-bus and the IEEE 14-bus test systems. Simulation results indicate that considering the pilot protection in the D&DOCRS coordination, not only obtains feasible and effective solutions for the relay settings, but also reduces the overall operating time of the protection system.
Y. Damchi, J. Sadeh, H. Rajabi Mashhadi,
Volume 11, Issue 3 (9-2015)
Abstract
Most studies in relay coordination have focused solely on coordination of overcurrent relays while distance relays are used as the main protection of transmission lines. Since, simultaneous coordination of these two types of relays can provide a better protection, in this paper, a new approach is proposed for simultaneous coordination of distance and directional overcurrent relays (D&DOCRs). Also, pursued by most of the previously published studies, the settings of D&DOCRs are usually determined based on a main network topology which may result in mis-coordination of relays when changes occur in the network topology. In the proposed method, in order to have a robust coordination, network topology changes are taken into account in the coordination problem. In the new formulation, coordination constraints for different network topologies are added to those of the main topology. A complex nonlinear optimization problem is derived to find the desirable relay settings. Then, the problem is solved using hybridized genetic algorithm (GA) with linear programming (LP) method (HGA). The proposed method is evaluated using the IEEE 14-bus test system. According to the results, a feasible and robust solution is obtained for D&DOCRs coordination while all constraints, which are due to different network topologies, are satisfied.
Y. Fattahyan, N. Ramezani, I. Ahmadi,
Volume 18, Issue 3 (9-2022)
Abstract
Using doubly-fed induction generator (DFIG) based onshore wind farms in power systems may lead to mal-operation of the second zone (Z2) of distance protection due to the uncertain number of available wind turbines on the one hand and the function of DFIGs control system to maintain the bus voltage on the other hand. In such cases, variable injected current by the wind farm causes distance relay fall in trouble to distinguish whether the fault point is in the Z2 operating area or not. In the current study, an adaptive settings scheme is proposed to determine the Z2 setting value of distance relays for such cases. The proposed method is based on the adaptive approach and the settings group facility of the commercial relays. The proposed method applies the k-means clustering approach to decrease the number of setting values calculated by the adaptive approach to the number of applicable settings group in the distance relay and uses the Particle Swarm Optimization (PSO) algorithms to achieve the optimum setting values. The high accuracy of the proposed method in comparison with other methods, suggested in the literatures, is shown by applying them to the IEEE 14-bus grid.
H. Yaghobi,
Volume 19, Issue 2 (6-2023)
Abstract
For reliable operation, distance relays have to be blocked in case of stable power swings (SPSs). Because these relays are prone to detect an SPS as a symmetrical 3-phase fault according to their symmetric nature. It should be noted that there are zero and negative sequence components during asymmetrical faults. However, these components do not exist during stable fluctuations or symmetrical faults. Consequently, according to the symmetric nature of the stable fluctuation, the distance relay may experience maloperation. This article proposes a new technique to discriminate a symmetrical 3-phase fault from an SPS. The proposed technique is based on the extraction of the exponentially decaying DC component in the 3-phase current by using the MIMIC impedance. This technique can detect the symmetrical fault in less than a quarter of one power cycle. The suitability of the technique is shown by simulating various symmetrical faults during fast and slow SPS conditions.
