This paper deals with the representation of price-responsive loads in the short term coordination of predominantly hydroelectric hydrothermal systems. The proposed approach allows the representation of cross-relationships between demand and price during different dispatch intervals of a given time horizon. Also, consumer energy constraints which behave as dynamic restrictions can be taken into account. By that means, a load shifting program in which the consumers' overall energy consumption remains constant throughout the time horizon can be simulated. The short-term hydrothermal coordination is solved as a single optimisation problem employing the primal–dual interior point method. Realistic subsystems, based on the Brazil interconnected power system, are used to illustrate the effect of price-responsive loads on reservoir storages.

This study presents a new methodology for modelling and handling with aggregated harmonic loads and linear loads in the harmonic power flow analysis. This method, so‐called variable load method, can be used in balanced and unbalanced systems and for deterministic and stochastic studies. The main types of harmonic loads and their participation coefficients inside the facility are estimated by inspection or based on usual values. In addition, a new type of load model that represents the load variation and minor loads is also defined based on field measurements, in order to build a more adherent harmonic load representation. A stochastic analysis, based on Monte Carlo simulations, is also performed. This sequence of steps makes possible to evaluate if the harmonic distortion has a significant probability of exceeding the limits set by standards because of load variations. This analysis is performed jointly with the bootstrapping method for obtaining the probability density functions of the voltage harmonic distortions. Tests on a real plant show that the proposed approach is able to represent measured data with high precision.