The increase in recent power failures, with negative impacts on humans and the economy, has been largely attributed to environmental effects and the aging of the power network. These have been accelerated in the last years due to two main factors: an increased load on the power network and material degradation owing to the presence of environmental pollutants. These factors together with specific weather conditions create the incipient conditions for power network degradation. In this paper, a review of the influence of environmental factors on high-voltage (HV) materials and components is provided. Sensing and artificial intelligence (AI) technologies developed to prevent the failure of the material structure and HV components are also reported.

Environmental Effects on HV Dielectric Materials and Related Sensing Technologies

The electric field distribution is one of the main factors governing the long-term reliability of high voltage composite insulators. However, under severe pollution conditions, electric field stresses, when exceeding thresholds and applying for long periods, could lead to degradation and deterioration of the housing materials and, therefore, to failures of the composite insulators. This paper is intended to improve the electric field and potential distributions by minimizing the corona discharge on a 400 kV AC transmission line composite insulator. The performances of three powerful multi-objective meta-heuristic algorithms, namely Ant Lion Optimizer (MOALO), Particle Swarm Optimizer (MOPSO), and non-dominated sorting genetic algorithm (NSGA-II) are established to achieve this goal. First, variations of electrical fields on the critical parts of the string are obtained using three-dimensional finite element method (FEM) software. Then, three objective functions are developed to establish the relationships between the electric field and the guard ring parameters. Finally, the optimization parameters consist of diameter, tube diameter, and installation height of the corona ring. The obtained results confirm the effectiveness of the three algorithms; the MOLAO is the better in terms of computing time and solution quality.

https://ieeexplore.ieee.org/ielx7/6287639/9668973/09729761.pdf

Multi-objective optimization of 400 kV Composite Insulator Corona Ring Design

This work presents an evaluation of electric field and electric potential in polymeric insulators under different operating conditions. The conditions considered were: intact insulator, with the presence of an external defect and under effect of pollution. Thus, two 138 kV polymeric insulators from different manufacturers were modeled with the aid of multiphysics simulation software that uses Finite Element Method. A thin conductive layer was modeled on the surface of the insulators, in order to investigate the influence of pollution on their electrical performance. The external defect was represented by a cavity deep enough to reach the interface between the coating and the core. In the simulations carried out on polluted insulators, it was detected that the insulator has a resistive characteristic, with low intensity electric field peaks. While the analysis of defective insulators showed that electric field suffers distortions, the intensity of this distortions was sufficient to cause air ionization, localized disruptive discharge and progressive degradation of the polymeric material. From the results obtained for each insulator, it was possible to observe electrical characteristics of the two topologies of polymeric insulators in view of application of different operating conditions

Comparative Analysis of Polimeric Insulators Under Pollution and External Defect Using the Finite Element Method

Reliability of service has always been an important priority in electric delivery planning and operation; traditionally it was treated as an implicit goal. Reliability as normally applied to power distribution means continuity of service to the utilitypsilas customers. In the term of a glossary of reliability standard, reliability is defined as the ability of the power delivery system to make continuously available of sufficient voltage, of satisfactory quality, to meet the customerpsilas need. In the development country like Indonesia to reach a high reliability index is still very difficult. Yogyakarta province as a part of Indonesia, the electric power supply is managed by Yogyakarta electric power distribution region that serve more than 650.000 customers and support by more than 11.000 power distribution transformers. These transformers are distributed along the line in the length of more than 10.000 kms. To improve the reliability of service one aspect to be paid attention is maintenance management of all the distribution equipments. With supported by CMMS system that is being developed, all of the maintenance management aspects are included in the system. The CMMS is developed on based of digitalizing distribution line networks, customerspsila connection, inventory of the assets, and man power. This CMMS also supported by GIS in conjunction with the reduction of the time needed to restore the system during fault.

Development of CMMS (Computerized Maintenance Management System) in Yogyakarta electric power distribution network company to support the strategic maintenance

El objetivo de este articulo es analizar las nuevas corrientes de actuacion en la gestion de activos, y su desarrollo y aplicacion en las companias electricas con objeto de afrontar con la mayor garantia posible la nueva caracterizacion del mercado en un entorno liberalizado. En este nuevo entorno resulta fundamental establecer una estrategia que permita gestionar el RIESGO, tanto en lo que se refiere al riesgo regulatorio como al asociado con el mercado de capitales y demas fuentes de financiacion. En nuestra opinion, es necesario un enfoque integral de Gestion de Activos que permita contemplar el analisis conjunto de las actividades de operacion y mantenimiento de los mismos (costes operativos) junto con las necesidades de inversion en nuevos elementos (gastos de capital), teniendo en cuenta al mismo tiempo el impacto producido por el marco regulatorio vigente en cada caso.
En la primera parte del articulo se analizan los principales cambios requeridos en la gestion de activos para su adaptacion a los entornos liberalizados actuales. En la segunda parte se describen nuevas practicas de planificacion, operacion y mantenimiento que permiten desarrollar el enfoque integrado de la Gestion de Activos. En la tercera parte del articulo se analiza el papel de los sistemas IT en el concepto integrado de Gestion de Activos. Por ultimo, se definen las caracteristicas generales que debe tener un plan de implantacion de las mejores practicas en Gestion de Activos.

Nuevas alternativas en la gestión de activos para compañías de transporte y distribución de energái eléctrica en mercados liberalizados

Although the cost of investment in power lines insulators is 3 - 5% of the total cost of the installation, the impact of their performance on reliability, failure costs, maintenance routines, etc in power systems is tens of times higher. Composite insulators were introduced 50 years ago and have been used around the world with consistently good experience. Low weight, easy handling, good performance under high pollution, low maintenance costs, and resistance to vandalism are some of their advantages. Nevertheless, acid rain, salty dust deposition, corona discharges, ozone, UV radiation, and humidity among other factors, deteriorate the quality of the polymeric housing reducing their hydrophobicity. The synergistic action of ageing factors is extremely complex and the whole degradation process may change when any one variable is slightly modified. Many studies have been carried out to increase understanding of the physicochemical processes which control the electrical and mechanical stability of polymers during in-service ageing with the objective of predicting remaining life-times. Vital areas of knowledge about polymer insulators are still incomplete and lacking; three of them are: (1) early stages of degradation in service under different environmental conditions, (2) monitoring and diagnosis techniques suitable for distribution installations and (3) steps to establish an insulators management plan based on condition and risk of failure.In this research these three topics are covered. A full review of literature about management of electrical distribution assets is included, followed by a specific plan developed for monitoring, diagnosis and ranking of insulators mainly supported by visual inspections. Diagnosis of medium voltages EPDM insulators recovered from service aged under different conditions is done using both traditional techniques and, uniquely, dielectric impedance. The relationship between surface roughness and static contact angle is also used to characterize insulators? surfaces. Early stages of degradation are studied focusing the experimental work to evaluate the electrohydrodynamic processes which occur on new samples under different conditions, giving special attention to leakage current pulse analysis, electric field enhancement, and resistance/capacitive behaviour including phase of leakage current. Results from each specific topic offer additional understanding of polymer insulators degradation providing insight to monitoring, diagnosis and management. Additionally, results open new topics in which new investigations are proposed.

Elizabeth Da Silva domingues

Papers

Improved Condition Monitoring of Composite Insulators