Tetsufumi Ohno

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This paper proposes a new method for line fault analysis of ungrounded distribution systems. The fault condition of a line fault is integrated into the nodal admittance matrix of the faulted line to be modeled. The zeroimpedance branch is merged into adjacent impedance branches to be taken into account, and one of its terminal buses with zero(More)
Abstract– This paper proposes a hybrid three-phase load flow method for ungrounded distribution systems. Based on topology connectivity analysis, the system is partitioned into a mainline system and multiple tap systems. A Newton method with constant admittance matrix is used to solve the mainline system, such that zero impedance branches are merged into(More)
This paper proposes a hybrid decoupled power flow method for balanced power distribution systems with distributed generation sources. The method formulates the power flow equations in active power and reactive power decoupled form with polar coordinates. Second-order terms are included in the active power mismatch iteration, and constant Jacobian and(More)
This paper proposes a new method for determining single-phase-to-ground fault locations of ungrounded distribution systems based on the measurements collected from the feeder breakers and intelligent switches during the fault. The method first narrows down the possible faulted area into a specific feeder section based on the reactive power factors of(More)
This paper proposes a new method for determining the location of single-phase-to-ground faults of ungrounded distribution systems based on residual voltage distribution. The possible faulted line segment and fault location are determined by comparing the phase angles of faulted phase voltages against a faulted phase reference angle, and the faulted phase(More)
This paper proposes a hybrid current profile based fault location algorithm for double-line-toground (DLG) faults in a distribution system. The method uses both short-circuit fault current profile (average of fault currents recorded for the faulted phases) and during-fault load current profile (corresponding to the un-faulted phase) to estimate an accurate(More)
This paper proposes a new distributed control method for three-phase reactive power control of distributed energy resources (DERs) in distribution systems. Each DER-connected bus has been equipped with a local bus controller which has bi-way communications with bus controllers at adjacent buses upstream and downstream to the bus under consideration. The(More)
This paper proposes a generalized admittance based method for fault location analysis of distribution systems. Based on the measurements collected from the feeder breakers and intelligent switches during a fault, the fault type and faulted feeder section are first determined by examining the over-voltages and over-currents on the breakers/switches. The load(More)
This paper proposes a generalized admittance based method for fault location analysis of distribution systems. Based on the measurements collected from the feeder breakers and intelligent switches during a fault, the fault type and faulted feeder section are first determined by examining the over-voltages and over-currents on the breakers/switches. The load(More)
This paper proposes a new method for determining locations of single-phase-to-ground faults in ungrounded distribution system using pre-fault and during-fault fundamental-frequency measurements. The pre-fault measurements along with the load profiles are used to determine load demands for each individual load in a feeder section. The during-fault(More)
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