Song Wennan

Fault location of two-parallel transmission line for non-earth fault using one-terminal data

Summary form only as given. An accurate fault-location algorithm for the two-parallel transmission line of a direct ground neutral system is presented. The algorithm employs the faulted circuit and healthy circuit of a two-parallel line as fault-location model, in which remote source impedance is not involved. It effectively eliminates the effect of load flow and fault resistance on the accuracy of fault location. It embodies an accurate location by measuring only one local end data and it is used in a procedure that provides the automatic determination of fault types and phases, rather than require an engineer to specify them. Simulation results have shown the effectiveness of the algorithm under the conditions of nonearth faults (phase-to-phase fault and three-phase fault with and without earth-connection).

Transmission line fault location for double phase-to-earth fault on non-direct-ground neutral system

An accurate algorithm for locating double phase-to-earth faults on transmission lines of nondirect ground neutral systems is presented. The algorithm employs the faulted phase network and zero-sequence network as the fault location model. It effectively eliminates the effect of load flow and fault resistance on the accuracy of fault location. The technique embodies an accurate location by measuring only one local end data. The algorithm is used in a procedure that provides the automatic determination of faulted line and phase, rather than requires engineer to specify them. Simulation results have shown the effectiveness of the algorithm under the condition of earth faults.

Power system static voltage stability limit and the identification of weak bus

This paper develops a new approach to find the power system static voltage stability limit using the conventional load flow solution method. The developed approach proposes a load admittance model to replace the load injection only on the heaviest load bus. Tested results in several systems show that the approach has advantages in terms of simplicity, flexibility, rapidity and accuracy. Based on the investigation of the voltage stability limits for the load buses, it is easy to identify the weak bus of the power system.<<ETX>>

A new transient energy function

Starting from normalized generators’ equations of rotor motion with respect to the center of inertia of power systems, post-fault power system dynamic is analogized as a motion of a particle with 1.0 mass in an n-dimensional Euclidean space. A rotational coordinate axis is defined for the moving particle. Transient stability of a multi-machine power system is transformed into a simple one-dimensional motion of particle on the axis. Based upon the above new idea, a new concept transient energy function (NCTEF) is proposed for transient stability assessment of power systems. Case studies on the 10-generator New England power system verified the rationality of NCTEF.

A MODIFIED THREE-PHASE MODEL OF TRANSFORMERS WITH DELTA-CONNECTED WINDINGS

ABSTRACT The currently used three—phase models [1-3] of transformers with delta—connected windings may lead to three—phase fundamental and harmonic bus admittance matrices of power systems with singularity, which may result in incorrect results or inability to carry out three—phase fundamental and / or harmonic load flow solutions. In order to solve this problem, this paper presents a modified model to keep the admittance matrices from singularity. Several samples and actual systems have proved the correctness and efficiency of the proposed model.

An accurate algorithm for fault distance estimation of two-parallel transmission line based on one-terminal sampling

An accurate numerical algorithm of fault location estimation for triple line-ground fault involving different phases from each of two-parallel lines is presented in this paper. It is based on one-terminal voltage and current data. The loop and node equations comparing faulted phase to nonfaulted phase of two-parallel lines are introduced in the fault location estimation modal, in which source impedance of remote end is not involved. The effect of load flow and fault resistance are effectively eliminated on the accuracy of fault location, therefore an accurate algorithm of locating a fault is derived. The algorithm is demonstrated by digital computer simulations.