Power Transformers (PTs) failures in electrical networks cause significant expenses for power utilities, making the use of assessment techniques essential to efficiently diagnose and estimate the actual operating conditions of such equipment’s. Efficient diagnoses allow operation management of this chain of assets aiming at the ideal balance among investments, maintenance costs and operation performance. Taking this into account, this paper presents an enhanced diagnostic methodology to estimate the PTs’ health based on simple and low-cost data which can be easily obtained without interrupting the unit's operation. The methodology uses data from oil sample analysis and acquisition systems of available electrical quantities and proposes the creation of a new diagnostic factor to identify the condition of the transformer's solid insulation. The new diagnostic factor is based on the history of the average daily load curve of a PT, allowing the estimation and accounting for the PT insulation degradation “in service”. Thus, the enhanced diagnostic methodology proposed in this work can estimate and update the transformerś health estimation in shorter time intervals than required by conventional Health Index (HI) methodologies and may be an important tool for strategic planning and resource optimization in power systems’ companies. The effectiveness of the proposed diagnostic methodology was assessed considering data from a population of 204 power transformers installed in Brazil and the direct comparison with the maintenance history from the conventional HI diagnostic methodology.

中文翻译：

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增强电力变压器健康指数诊断

电网中的电力变压器 (PT) 故障会给电力公司带来巨额费用，因此使用评估技术对于有效诊断和估计此类设备的实际运行状况至关重要。高效的诊断可以对这条资产链进行运营管理，以实现投资、维护成本和运营绩效之间的理想平衡。考虑到这一点，本文提出了一种增强的诊断方法，基于简单且低成本的数据来估计 PT 的健康状况，这些数据可以在不中断设备运行的情况下轻松获得。该方法使用来自油样分析和可用电量采集系统的数据，并建议创建一个新的诊断因素来识别变压器固体绝缘的状况。新的诊断因素基于 PT 平均每日负载曲线的历史记录，允许估计和解释“使用中”的 PT 绝缘退化。因此，本工作中提出的增强诊断方法可以在比传统健康指数（HI）方法所需的更短的时间间隔内估计和更新变压器的健康状况估计，并且可能是电力系统公司战略规划和资源优化的重要工具。考虑到巴西安装的 204 个电力变压器的数据以及与传统 HI 诊断方法的维护历史的直接比较，评估了所提出的诊断方法的有效性。