Due to the complexity of the valve side winding voltage of the converter transformer, the insulation characteristics of the oil-impregnated pressboard(OIP) of the converter transformer are different from those of the ...
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Due to the complexity of the valve side winding voltage of the converter transformer, the insulation characteristics of the oil-impregnated pressboard(OIP) of the converter transformer are different from those of the traditional AC transformer. The study on effect of temperature on the creeping discharge characteristics of OIP under combined AC–DC voltage is seriously inadequate. Therefore, this paper investigates the characteristics of OIP creepage discharge under combined AC–DC voltage and discusses the influence of temperature on creepage discharge characteristics under different temperatures from 70 °C to 110 °C. The experimental results show that the partial discharge inception voltage and flashover voltage decrease with increasing temperature. The times of low amplitude discharge(LAD) decrease and amplitude of LAD increases. Simultaneously, the times of high amplitude discharge(HAD) gradually increase at each stage of creepage discharge with higher temperature. The analysis indicates that the charge carriers easily accumulate and quickly migrate directional movement along the electric field ahead of discharging. The residual charge carriers are more easily dissipated after *** ‘hump’ region of LAD moves to the direction of higher discharge magnitude. The interval time between two continuous discharges is shortened obviously. The concentration of HAD accelerates the development of OIP insulation creepage discharge. The temperature had an accelerating effect on the development of discharge in the OIP under applying voltage.
Solid oxide fuel cell combined with heat and power(SOFC-CHP)system is a distributed powergeneration system with low pollution and high *** this paper,a 10 kW SOFC-CHP system model using syngas was built in Aspen *** ...
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Solid oxide fuel cell combined with heat and power(SOFC-CHP)system is a distributed powergeneration system with low pollution and high *** this paper,a 10 kW SOFC-CHP system model using syngas was built in Aspen *** operating parameters,such as steam to fuel ratio,stack temperature,reformer temperature,air flow rate,and air preheating temperature,were *** was conducted based on the simulation *** suggest that higher steam to fuel ratio is beneficial to the electrical efficiency,but it might decrease the gross system *** stack and reformer temperatures contribute to the electrical efficiency,and the optimal operating temperatures of stack and reformer when considering the stack degradation are 750℃and 700℃,*** air preheating temperature barely affects the electrical efficiency but affects the thermal efficiency and the gross system efficiency,the recommended value is around 600℃under the reference condition.
The article designs a new type of bridge circuit with a controlled source—when the resistance on the bridge arm of the controlled source bridge circuit meets the bridge balance condition, and the bridge branch contai...
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The article designs a new type of bridge circuit with a controlled source—when the resistance on the bridge arm of the controlled source bridge circuit meets the bridge balance condition, and the bridge branch contains only one Current-controlled Current Source (CCCS), a Voltage-controlled Current Source (VCCS), a Current-controlled Voltage Source (CCVS), or a Voltage-controlled Voltage Source (VCVS), the circuit is called a controlled bridge circuit, which has the characteristics of bridge balance. Due to the relationship between the controlled source and the bridge arm, the sensitivity of the components on the bridge is higher mathematically and logically. When applied to measurement, engineering, automatic control, and other fields, the controlled bridge circuit has higher control ac-curacy. Mathematical derivation and simulation results prove the correctness of the bridge balance conclusion and the special properties of this bridge when applied to the measurement field.
Uncertainty is not negligible in powersystems, it affects the generation, transmission and utilization of electricity. Especially in electricity markets, the randomness and variability of generation or load will caus...
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Five-level active neutral-point-clamped (ANPC) converter is a newly emerging topology which can overcome the drawbacks of traditional neutral-point-clamped and flying-capacitor multilevel converters. During the start-...
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IPS has many special characteristics, such as using multi-phase, multi-frequency and hybrid AC/DC devices. As a result, existing electromagnetic transient simulators developed for powersystems on land do not apply to...
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Conventional steady-state security analysis have to compute the faults belonging to the predefined faults set in turn with out considering the small probability of the occurrence of some faults under certain circumsta...
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Travelling wave (TW) differential protection fully utilizes the fault information contained in TW at both terminals of a transmission line, so it's a protection with high reliability and high selectivity. However,...
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ISBN:
(纸本)9781785618260
Travelling wave (TW) differential protection fully utilizes the fault information contained in TW at both terminals of a transmission line, so it's a protection with high reliability and high selectivity. However, because TW differential protection needs a large amount of communication, it cannot be put into practical use. This paper proposes a TW differential protection which is based on equivalent travelling wave (ETW). Fault information is not lost during the process of getting ETW, so the proposed protection has the same reliability and selectivity with traditional TW differential protection. Because only several modulus maxima are needed to be sent to the opposite terminal, the traffic is largely reduced and the protection can operate much more rapidly. Extensive simulations validate the proposed protection.
Performance evolution of typical Ni-YSZ anode-supported SOFCs during the initial-stage operation ( 20 h), regardless of the operating current. In the activation stage, the cell performance maintains stable or slightly...
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With the rapid development of distributed energy resources (DERs), it is of vital importance to develop a well-designed transmission cost allocation scheme to reflect the contributions of DERs to the power system. In ...
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