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This paper evaluates the maximum potential rise on the traction earth (TE) conductor caused by stray currents in the Taipei Rail Transit Systems (TRTS). The stray current from the TRTS will flow into the earth due to the voltage difference along the running rails caused by the traction currents returning to the substations. The potential rise of 0.1 V is admitted in international recommendations as the maximum acceptable value for corrosion protection of utilities outside a dc railway system. Since TRTS is one of the dc-traction rail transit systems, it may cause corrosion or other effects by stray currents to the existing underground metallic structures. As a result, the purpose of this paper is to evaluate whether the maximum potential rise on the TE conductor caused by stray currents from IRTS is greater than the maximum permissible value 0.1 V or not. [ABSTRACT FROM AUTHOR]

This paper presents a practical case for the safety assessment of ground grid design at 161/69-kV indoor-type and out- door-type substations in the system of Taiwan Power Company (TPC). For a substation grounding system to be safe, the touch and step voltages should be limited below the minimum tolerable voltages. Since the mesh voltage is usually the worst possible touch voltage inside an ac substation (excluding transferred potentials), the mesh voltage is used as the criteria for a safe ground grid design. In other words, safety assessment of a ground grid design at 161/69-kV indoor-type and outdoor-type substations in the TPC system is referred to as a procedure by which the mesh and step voltages at substations are computed and compared to the minimum touch and step voltages. Computation results of safety assessment for humans with 50- and 70-kg body weight are quantified in this paper. [ABSTRACT FROM AUTHOR]

This paper proposes an alternative data envelopment analysis method to explore the efficiency, the resource allocation, and the benchmarks of the electricity distribution districts (EDD5) of Taiwan Power Company in 2003. Several empirical results are shown: 1) the EDDs covering the high-tech industry park are more efficient, on average, than ones involved in the nonhigh-tech industry park; 2) the EDDs located in urban areas outperform those located in rural areas; 3) the large-sized EDDs generally are more able to integrate their resources and to operate efficiently; 4) the benchmark-share measure shows that while small-size efficient EDDs can easily become benchmarks, large-size efficient EDDs are deemed as competitive niche players; and finally, 5) the effect on these EDDs merging their activities should be investigated to explore the possibility of increasing competitive advantage in the future. [ABSTRACT FROM AUTHOR]

The "318 Blackout Incident" at the Maanshan Nuclear Power Station on March 18, 2001, is considered to be the most serious event over the 24-year history of nuclear power generation in Taiwan. This paper simulates a special overvoltage phenomenon that occurred 4 h before the blackout event, which could have caused the incident. The simulation results almost coincide closely with the actual conditions recorded. We found two major low-frequency and ferroresonant overvoltages caused by the motors which acted as generators when they lost power supply, interacting with power-line capacitance and power transformers. Since overvoltages were present for a short period, the breaker insulation did not break down immediately but the defects were accumulated. A blackout eventually occurred 4 h later, when the power supplied to the 4.16-kV essential bus A changed over from the 161-kV system to the 345-kV system, due to damage in the incoming breaker insulation. [ABSTRACT FROM AUTHOR]

Taipei Metro adopted the diode-grounded scheme for stray current collection in construction of its cross rail network. During operation of the network, a high rail-to-earth potential (Vrail) has been observed at the east end of the Blue Line (i.e., stations BL13-BL16). To find effective countermeasures, a series of field tests in a step-by-step development nature was conducted from 1999-2000, which led to the decision of disconnecting the impedance bond at Gil of the tie line so that the negative return current of the Blue Line cannot flow to the rails of the Red-Green Line, and vice versa (detailed in Sections 111-A and V-C). This decision was implemented through contract-out work in 2003. Since then, the Vrail has been lowered by almost half before disconnection. To gain the insight characteristic before the contract-out, numerical simulations were also conducted by simulating the multi-train and multisection features of the cross transportation network. The simulation results (for Vrail and stray current, or Istray) were consistent with the field-test results. This paper presents the design of these field tests and their test results in comparison with the simulation results, based on which the countermeasures for reducing Vrail and the present status after Vrail reduction at Taipei Metro are presented. [ABSTRACT FROM AUTHOR]

This paper describes the application of proposed under-frequency load shedding scheme with dynamic D-factors, i.e., load frequency and voltage dependent coefficients, of various dynamic load models to Taiwan power system. The load models adopted are 1) a single-motor dynamic model, 2) a two motor (one small and one large) dynamic model, and 3) a composite (static and dynamic) model. First, the dynamic D -factor values of these load models are determined by the actual analytical approach employed in Taiwan power system. Then, a single-machine model representing a multi-machine power system is utilized for validating the proposed load shedding scheme with derived dynamic D-factor values. Finally, time simulation results of load shedding applied to various load models are compared with field measurement data, which are obtained from Taiwan power system in the case of three-phase short circuit fault, to evaluate the effects of different load models on the proposed load shedding scheme, based on the restoration of system frequency. [ABSTRACT FROM AUTHOR]