Search

Conventionally, the 2-parameter Weibull model, Arrhenius-Weibull model, has been used vastly for transformer aging-dependent unavailability modeling. However, this model only uses the lifetime feature to describe the transformer's degradation process and to calibrate the Weibull parameters, which harms the accuracy of aging-dependent unavailability forecasting. In response, this paper develops a 3-calibratable-parameter Weibull model for evaluating the transformer aging-dependent unavailability. In the proposed model, both the individualized aging threshold and lifetime are taken into the calibration of the Weibull parameters to accurately characterize the heterogeneity in transformer populations. First, a degree of polymerization (DP) analysis and Monte Carlo Simulation (MCS) based approach is proposed for estimating the transformers’ uncertain aging thresholds and lifetimes. Then, the Maximum Likelihood Estimate and Particle Swarm Optimization are jointly adopted to model the relationship among the calibratable Weibull parameters, aging threshold, and lifetime. Finally, the analytical formula of aging-dependent unavailability is derived from the established 3-calibratable-parameter Weibull model using an integral-discretization method. A real utility application example in China's Chongqing power system has been presented to validate and demonstrate the practicality and usefulness of this method. [ABSTRACT FROM AUTHOR]

Faults on the alternating current (AC) transmission lines could cause commutation failures of nearby line-commutated converter-based high-voltage direct-current (LCC-HVDC) systems, which in turn, may challenge the fault detection of AC systems. To address this issue, this paper proposes a fast fault detection method based on instantaneous active power and fault variation component to alleviate the impacts of commutation failures and reactive power compensation while mitigating the dead zone problem. Upon that, an integral-based differential protection algorithm is presented to enhance reliability. Simulations are carried out on a real hybrid AC/DC system in North China with different fault locations and resistances to verify the effectiveness of the proposed method. Finally, we further validate the proposed method by leveraging on-site recorded fault data. [ABSTRACT FROM AUTHOR]

The smart substation, revolutionarily changing every aspect of the modern substation, is developing fast in the world and being massively deployed in China quickly. A smart substation is typically implemented with a sophisticated combination of smart primary high-voltage equipment and hierarchically networked secondary devices. Based on the IEC61850 communication protocol, the functionalities, such as the information sharing and interoperability among smart electric equipment, are realized in smart substations. It is regarded as the basis for the development of smart grid and represents the future development trend of substation technologies. This paper reviews the fundamental vision of the smart substation. The state of the art and the challenges encountered in the practice of engineering implementation are presented. Future developments to solve the present challenges and promote the development of smart substations are also described. [ABSTRACT FROM PUBLISHER]