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The displacement of synchronous generators by converter interfaced energy renewable resource essentially reduces the system inertia, which can trigger under-frequency load shedding relay. To support the frequency containment, virtual inertia control (VIC) and fast frequency control (FFC) based on energy storage system (ESS) have been developed. Most of the existing VIC did not take into account the power constraints of the ESS. Although some of the FFC methods account for the ESS constraints, they ignore the intermediate steady-state (ISS) operating point of the primary frequency response (PFR). To counteract these problems, a model predictive control (MPC) based FFC, which considers the power limitations of the ESS, the frequency deviation constraint, and the ISS frequency tracking capability, is proposed in this paper. The proposed MPC only requires few local measurements, and the system parameters including inertia constants, onset time of inertia response and the ISS time of the PFR can be accurately estimated. To achieve the optimal control action and reduce computational burden, quadratic programming (QP) is incorporated in the proposed MPC. The proposed MPC is tested on a real Taiwan power system. The fast response and robustness of the proposed MPC has been justified by comparing with the state-of-the-art method. [ABSTRACT FROM AUTHOR]

In a power system, the transmission network is the backbone of electricity delivery from power plants to load centers; hence, it becomes a critical issue for electrical engineers to shorten the service restoration time after a fault occurrence on the transmission line. This application paper integrates the two- and three-terminal hybrid transmission line fault location algorithms based on synchronized phasor measurements into the proposed cloud-computing-based fault location system to inspect the feasibility and practicality of our algorithms for the real transmission-line incidents. The computing results are performed via Google Map for authorized personal computers and the application for intelligent mobile devices is developed to assist engineers in acquiring the fault-event information immediately as well as in figuring out the fault position intuitively and quickly due to its visualization and navigation. Last but not the least, the suggested fault location system has already been applied to the practical 345- and 161-kV transmission networks of Taiwan Power Company for achieving the combination of theory and practice. Up to the present, the proposed system still yields excellent performance verified by realistic fault data. [ABSTRACT FROM AUTHOR]

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]

The severe insulation breakdown on one medium-voltage (MV) switchgear led to a complete blackout of Taipower's 3rd nuclear power plant on March 18th, 2001. This has been one of the most serious incidents during the past 30 years of Taipower's nuclear generation and while the cause of the event was a combination of design, maintenance, and equipment aging issue, it is apparent that repeated switching operation on the extra-high-voltage (EHV) side eventually caused this severe insulation breakdown on MV switchgear. Very-fast transient overvoltage (VFTO) is the phenomenon of transient overvoltage generated during switching operation characterized by a very short rise time of 4 to 100 ns. Prior research on this topic focused on VFTO's impact on the EHV side of the transformer and this paper presents the field measurement result together with long-duration multiple-restrike simulation for the VFTO transferred from the EHV side to the MV system through the power transformers. It is shown that this VFTO can be as high as 7 times the rated line-to-ground peak voltage and the maximum VFTO often occusr neither at the first nor at the last strike due to the superposition of restriking voltage on top of oscillation voltage created by prior strikes. [ABSTRACT FROM AUTHOR]

The subject of this paper is to construct a current-transformer (CT) model based on the Jiles-Atherton (J-A) theory of ferromagnetic hysteresis using transient analysis of control systems (TACS) functions within the Electromagnetic Transients Program (EMTP) in a closed-loop manner. The J-A theory of ferromagnetic hysteresis is presented by the nonlinear first-order ordinary differential equations and inclusive of five parameters that can be found by measurements of hysteresis characteristic. We can use TACS functions within EMTP to describe the J-A theory of ferromagnetic hysteresis. The powerful advantage of this way is the interaction between the electrical network and TACS in EMTP. Compared with the CT model based on the type 96 nonlinear hysteresis inductor, the simulated result of the CT model based on the J-A theory of ferromagnetic hysteresis is almost the same in steady-state situations, but apparently different in a fault transient situation. The analysis and simulation of the actual measured fault profiles in the Taiwan power system is an example of the validation of this proposed model. Therefore, this proposed CT model based on the J-A theory of ferromagnetic hysteresis has the analysis capability of the transient response. The flexibility of TACS makes the simulation of any other situation easier and is another advantage. [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]

This paper presents a practical case for safety assessment of bulk supply substations (BSS) and traction supply substations (TSS) in Taipei Rail Transit Systems (TRTS). For a substation grounding system to be safe, the maximum touch-and-step voltages should not exceed postulated safety criteria. The safety criterion in IEEE Standard 80 is defined in terms of permissible body current. The permissible body current is then translated into the permissible touch-and-step voltages. Since the mesh voltage is usually the worst possible touch voltage inside the substation (excluding transferred potentials), the mesh voltage is used as the safety criteria. In other words, safety assessment of an ac substation grounding system in TRTS is referred to a procedure by which the mesh and step voltages are computed and compared to the maximum permissible (safe) touch-and-step voltages. Computation results for the orange line at 019 station are presented. [ABSTRACT FROM AUTHOR]