Assessment of aggregation strategies for machine-learning based short-term load forecasting

Abstract

Effective short-term load forecasting (STLF) plays an important role in power system operations. It is challenging to identify an ML model that has the outperformance in all scenarios. Therefore, there are a number of aggregation strategies developed to improve STLF. However, the superiority of these aggregation strategies has not been assessed. In this paper, STLF with three aggregation strategies are developed, which are information aggregation (IA), model aggregation (MA), and hierarchy aggregation (HA). The IA, MA, and HA strategies aggregate inputs, models, and forecasts at the pre-forecasting, model-building, or post-forecasting stage, respectively. To verify the effectiveness of the three aggregation strategies, a set of 10 models based on 4 machine-learning algorithms are developed in each aggregation category to predict 1-hour-ahead load. Case studies show that: (i) STLF-IA presents superior performance than STLF with weather data and STLF with individual load data consistently, and the performance can be further enhanced by the recursive feature elemination (RFE) feature selection method; (ii) MA improves the STLF robustness by reducing the risk of unsatisfactory single-algorithm STLF models; and (iii) STLF-HA produces the most accurate forecasts with a 0.83% normalized mean absolute error and a 1.35% mean absolute percentage error, while keeping hierarchical aggregate consistency.