Publication Date: 2021
Electric Power Systems Research (03787796)
This paper proposes a new unsynchronized parameter-free fault location scheme for transmission lines (an overhead line (OHL) combined with an underground cable (UGC)). Utilizing unsynchronized measurements at both ends, the proposed method accurately locates faults without requiring OHL and UGC parameters. Therefore, the variation of OHL and UGC parameters values do not affect its accuracy. In this method, first using distributed line model for UGC and OHL, the fault location problem is converted into a system of nonlinear equations problem according to both pre-fault and fault measurements. Then, using a novel algorithm, the system of nonlinear equations is solved. This algorithm consists of two stages which in the first one, the system of nonlinear equations is converted into an optimization problem and in the next stage, using the first stage results, the problem is solved by a modified Newton method. Simulation results performed by MATLAB, verify the high accuracy of the proposed method in determining the fault location (whether in UGC or in OHL). In these simulations, it is shown that the proposed method is independent of the fault resistance, synchronization angle, and fault type and consequently, is superior to the existing methods. Moreover, the simulation results confirm the ability and efficiency of the proposed model in estimating OHL and UGC parameters. © 2020 Elsevier B.V.
Publication Date: 2020
IET Renewable Power Generation (17521416)(4)
This study presents a new control scheme to provide both voltage regulation and power sharing within a DC microgrid. It includes both primary and secondary levels as well as the proposed auxiliary feedback. The secondary control distributes and uses the consensus algorithm to share power. First, the auxiliary feedback is formulated. Then the features of the feedback are analytically extracted to provide both voltage regulation and power sharing. Next, the particle swarm optimisation algorithm determines the parameters of the controller optimally. Following that, a series of simulations is carried out to show the performance of the proposed scheme in comparison with the conventional methods. Hence, to validate the advantages of the proposed scheme, a four distributed energy resource (DER) DC microgrid is considered, and the proposed approach is applied. Afterwards, the eigenvalue and sensitivity analysis show the effect of the parameters variation on microgrid stability. The results show that the applied method can regulate the voltage well and shares the power in the presence of the load demand as a disturbance besides the long-time delay associated with the secondary control as an uncertainty. © The Institution of Engineering and Technology 2019.
