Restoration of Directional Overcurrent Relay Coordination in Distributed Generation Systems Utilizing Fault Current Limiter
ABSTRACT A new approach is proposed to solve the directional overcurrent relay coordination problem, which arises from installing distributed generation (DG) in looped power delivery systems (PDS). This approach involves the implementation of a fault current limiter (FCL) to locally limit the DG fault current, and thus restore the original relay coordination. The proposed restoration approach is carried out without altering the original relay settings or disconnecting DGs from PDSs during fault. Therefore, it is applicable to both the current practice of disconnecting DGs from PDSs, and the emergent trend of keeping DGs in PDSs during fault. The process of selecting FCL impedance type (inductive or resistive) and its minimum value is illustrated. Three scenarios are discussed: no DG, the implementation of DG with FCL and without FCL. Various simulations are carried out for both single- and multi-DG existence, and different DG and fault locations. The obtained results are reported and discussed.
- [Show abstract] [Hide abstract]
ABSTRACT: This paper presents a novel fault current management (FCM) technique for radial distribution systems with embedded inverter-based distributed generators (IB-DGs). At the point of connection to a power system, many distributed generators (DGs) require power electronic (PE) interfaces, which are normally idle during faults. The proposed FCM method employs these PE interfaces for control of the fault current. For this purpose, operation of IB-DGs is modified to FCM mode at the moment of fault and new current references are applied. Of the two controllable parameters of the IB-DG output current—current magnitude and current phase angle—the current phase angle is chosen as the means of controlling the fault current magnitude. The reference current phase angle is calculated based on the relation between the fault current elements and their phase angles. As a result of this novel operation, IB-DGs with larger capacity can be connected at different locations of the system without affecting the fault current magnitude. Also, implementing this technique in smart grids is economically proven, since the asset of power system which have been designed for normal operation are employed to manage the fault current magnitude. Moreover, possibilities of synchronization problems are reduced by keeping IB-DGs connected to the system at all the time. The evaluation of the proposed FCM technique using the standard IEEE 33-bus distribution system demonstrates the effectiveness of the proposed method for managing the fault current magnitude.IEEE Transactions on Smart Grid 09/2014; 5(5):2183-2193. · 4.33 Impact Factor
- International Journal of Electrical Power & Energy Systems 10/2014; 61:463–473. · 3.43 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: This paper presents a new approach for optimal coordination of over current relay in a power delivery system (PDS). For this, the relay coordination problem is formulated as the optimization problem by minimizing the relays operation times. Also, an efficient hybrid algorithm based on Shuffled Frog Leaping (SFL) algorithm and linear programming (LP) is introduced for solving complex and non-convex optimization problem. To investigate the ability of the proposed method, a 30-bus IEEE test system is considered. Also, to validate the obtained result by SFL-LP, a GA-LP method is applied. Simulation results show the efficiency of proposed method.