A Novel Approach for Fault Observability and Isolation in Distributed Power System using PMUs

A Novel Approach for Fault Observability and Isolation in Distributed Power System using PMUs
Authors:M.DINESH REDDY, SHAIK HAMEED

Abstract: In a Distributed Power System (DPS), the occurrence of line faults is very frequent due to natural threats to the lines and their ageing. In a big distributed network a fault is occurred at one corner part of the network shows a serious impact on the entire network by causing a severe deviation in its operation there by leading to shut-down of the entire network until or unless the fault was detected and isolated. In this project in order to resolve the above issues we proposed a novel algorithm for DPS security by replacing IEDs in former algorithm with Pharos Measurement Units(PMUs)which determines the occurrence of the faults based on the analysis of voltage and current phasors of Power Distribution Bus (PDB) lines. The method exploits the nodal voltage and mesh current analysis where the phase voltage, impedance and admittance matrices of the network and its dual circuit are developed and utilized for smooth detection and isolation of faults without network malfunction. In addition, this method not only detects and isolates the faults but also informs the same to the technical department for immediate correction. The PMUs are organized as independent region monitoring devices controlled by the control unit of Distributed Power System. The proposed algorithm is implemented and verified in MATLAB. 

Keywords: Distributed Power System (DPS), IEDs, Pharos Measurement Units(PMUs). 

INTRODUCTION 

       Faults and device failures affect the power quality in power systems and cause losses for both electric utilities and customers [1]. In distributed generation [4], safety and secure operation of the system highly rely on the level of power system operating condition monitoring. In traditional approaches the measurements provided by the remote terminal units (RTU) at the substations are sent to the control center. This data include real/reactive power in different lines as well as bus voltages and branch currents. The unmeasured states of the system are then estimated by state estimators that reside in the control center. Normal observability in power system is defined as knowing the voltage phasors of all the buses. Fault observability [18], on the other hand, is defined such that a system becomes fault observable when the voltage at two ends of each line and the current at any end of the line are determinable. In general, a system, which is observable in the normal condition, may not be observable for the fault condition. In this project the application of PMUs in fault location [15] is investigated and a method is proposed to effectively reduce the number of required PMUs [16] while retaining the accuracy of fault location [15]. Thus, fault observability [18] is the main focus in this work. In a big distributed network a fault is occurred at one corner part of the network shows a serious impact on the entire network by causing a severe deviation in its operation there by leading to shut-down of the entire network until or unless the fault was detected and isolated. This will lead to a heavy loss to the consumers and industries as it disturbs the production process. Unlike traditional AC distribution systems, protection has been challenging for DC systems. 

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