Adverse weather conditions can have a significant impact on electricity network infrastructure and will subsequently compromise the quality of power delivered to consumers. A study on the effects of climate change on the US electrical network concluded that
of all large scale power outages between 2003 and 2012 were caused by weather and the average number of weather related outages per year doubled during those years [
1]. Although some results refer to weather conditions specific to the US climate, they are indicative of how changing weather conditions can affect the electricity network. In the UK, the distribution network operators have published climate adaptation reports, outlining the current risks and the anticipated impacts as a result of a changing climate. Among others, ref. [
2] discusses the main results of a study conducted with the UK Met Office regarding the impacts on the electricity network, which identified the major causes of weather related outages and estimated how their frequency might change in the future. Using the Met Office climate projections [
3], the study showed that there is an uncertainty regarding the future occurrence of wind related faults, as there is uncertainty in the wind gust projections as well. However, the number of lightning related faults is more likely to increase and the faults due to snow, sleet and blizzard are estimated to be fewer but with the same or increased intensity.
1.2. Related Work
The weather related impacts on the power system and the uncertainties accompanying climate change have been a recurring research subject of the academic and power industry sectors. The existing research on weather related fault prediction is reviewed in this section, which concludes with the contribution of the work presented in this paper and how it differs from the previously conducted research.
A review of the research addressing the impacts of extreme weather on the power systems’ resilience is presented in [
4], where a framework for the modelling of weather related impacts on power systems is proposed. A methodology based on this framework is developed in [
5], where the effects of windstorms on the transmission network’s resilience are assessed, utilising real time weather conditions and calculating the weather dependent failure probabilities. The application of this methodology on the GB transmission network determined the critical wind speed above which there was a sharp increase in the event occurrences per year.
The effect of wind on the GB transmission system was also investigated in [
6], where historical data was used to identify the relationship between wind gust and fault occurrence. The work presented in this paper concluded that, when extreme values of wind gust are observed there is a higher probability for a wind related fault to occur. The occurrence, intensity and duration of wind storms in the northeast US are modelled in [
7]. Subsequently, the dependencies of weather and component failure are investigated, and the risk of failure is quantified for the components of a real distribution system.
Weather data have been used as part of an improved protection strategy called hierarchically coordinated protection [
8,
9]. Unlike other fault prediction approaches which aim to prevent the occurrence of a fault, the purpose of prediction in hierarchically coordinated protection is to give the utilities the opportunity to anticipate a weather-related fault and be better prepared to deal with it. This approach utilises weather data and machine learning techniques such as Neural Networks or Support Vector Machines to detect and classify the potential faults. Then, when a fault is detected and recognised by the system, the protection is adjusted based on the type of the fault. The prediction of occurrence and location of weather-related faults in the distribution network was also examined in [
10] which provides a comparison of machine learning models developed for this purpose. Again, the aim of these predictive models, which utilised grid electrical parameters and infrastructure type alongside historical weather and fault data, was to enhance preparedness for an event rather than preventing it.
The use of historical weather data alongside a number of other data sources such as customer calls and Smart Meter data, geographical information system data, asset condition data etc, for post fault analysis is proposed in [
11]. Work utilising the above ideas is presented in [
12,
13], where historical and real time weather data are analysed alongside data from various other sources in order to provide an understanding of the effects that different nature-caused events have on the network and produce risk maps for weather-related outages using a geographical information system framework and fuzzy logic, respectively.
Weather conditions and lightning strike positions have been used in addition to data from remote power quality monitoring devices to improve their predictive maintenance system by detecting incipient equipment failure in [
14], while in [
15] wind speed data in conjunction with component resiliency index and distance from the hurricane centre have been used as inputs to a Support Vector Machine model, in order to predict an electrical grid component outage following a hurricane.
Data from maintenance tickets, features related to equipment vulnerability and various weather-related features, mostly related to temperature and precipitation to model monthly weather conditions have been used for the modelling approach presented in [
16]. The aim of this model was to gain an insight of the weather factors that significantly affect the power grid and, subsequently, lead to serious events and model their dependencies.
A framework to predict the duration of distribution system outages is presented in [
17]. Using outage reports and their respective repair logs in conjunction with weather data, it was found that certain weather features were correlated with specific causes and good results could be achieved, even when taking only weather data into account. The inclusion of information contained in the outage reports and repair logs was found to enhance the model’s performance.
An analysis of the correlation between failures and weather conditions is presented in [
18], where market basket style analysis is used to generate predictive rules using weather data which has been earlier categorised as “high”, “medium” or “low”. The analysis gave a moderate accuracy of prediction but indicated that there is potential in using weather forecasts to predict component failure. In [
19], an extended version of logistic regression is used to perform a probabilistic classification and calculate the probability of a fault occurrence given information regarding the weather conditions, location, time and operating voltage.
The relationship between weather conditions and the total number of interruptions is examined in [
20], where historical weather data and daily number of failures are considered in order to predict the total number of weather related failures in a year. The purpose of this work is to assess the network’s performance by the end of the year by comparing the actual and the previously predicted number of failures. Similar work is presented in [
21], where a Neural Network based model is developed to predict the total number of interruptions and not only those that are directly caused by weather conditions.
The previously conducted research presented above, gives an idea of how weather data have been used to predict weather related faults for various applications. The first examples of research work discussed, refer to fault prediction at the transmission level and wind is the environmental factor that is predominantly considered. Next, the relevant work at the distribution level was discussed. The majority of this work utilises a substantial amount of data, coming from various sources alongside the weather data that they use. Two of the papers presented above [
20,
21], make use of weather data and number of failures only but their purpose is to predict the total number of interruptions in a region. Another [
18], aims to predict a component failure using only weather data but, instead of using the actual measurements, they have previously classified them in three categories (high, medium, low). In contrast, the research work presented in this paper aims to assess the impact of weather on the occurrence of distribution network faults in the absence of extensive monitoring. As the distribution networks in the UK are usually minimally observed, this work utilises already existing meteorological data from local Met Office weather stations and fault records provided by a UK Distribution Network Operator, in order to predict a weather related fault occurrence at a given location. This work extends the fault prediction methodology down to the LV level of the distribution network and follows an ensemble approach, which unifies a range of identified fault relations as these were captured by a number of machine learning methods, allowing the benefits of different techniques to be combined in a single model. The machine learning methods used in this paper have already been used in the literature to address various applications and no new techniques are proposed as part of this paper. The motivation for using machine learning was to address the unknown physics of the individual fault cause processes. Identifying the most suitable methods for this specific task and combining them in an ensemble model that retains the strengths of individual models results in the development of fault prediction models for the HV and LV distribution network that can have a significant impact from a practical point of view.
The remainder of this paper is organised as follows. The network operator data and context are described in
Section 2. In
Section 3, the machine learning methods and the data analysis process are described, while the results are presented and discussed in the three case studies of
Section 4. Finally, a brief summary and conclusion discussing the operational benefit of this research are given in
Section 5.