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An alternative approach to characterise real voltage dips is proposed and evaluated in this study. The proposed methodology is based on voltage-space vector solutions, identifying parameters for ellipses trajectories by using the leastsquares algorithm applied on a sliding window along the disturbance. The most likely patterns are then estimated through a clustering process based on the k-means algorithm. The objective is to offer an efficient and easily implemented alternative to characterise faults and visualise the most likely instantaneous phase-voltage evolution during events through their corresponding voltage-space vector trajectories. This novel solution minimises the data to be stored but maintains extensive information about the dips including starting and ending transients. The proposed methodology has been applied satisfactorily to real voltage dips obtained from intensive field-measurement campaigns carried out in a Spanish wind power plant up to a time period of several years. A comparison to traditional minimum root mean square-voltage and time-duration classifications is also included in this study. [ABSTRACT FROM AUTHOR]

An alternative approach to characterise real voltage dips is proposed and evaluated in this study. The proposed methodology is based on voltage‐space vector solutions, identifying parameters for ellipses trajectories by using the least‐squares algorithm applied on a sliding window along the disturbance. The most likely patterns are then estimated through a clustering process based on the k‐means algorithm. The objective is to offer an efficient and easily implemented alternative to characterise faults and visualise the most likely instantaneous phase‐voltage evolution during events through their corresponding voltage‐space vector trajectories. This novel solution minimises the data to be stored but maintains extensive information about the dips including starting and ending transients. The proposed methodology has been applied satisfactorily to real voltage dips obtained from intensive field‐measurement campaigns carried out in a Spanish wind power plant up to a time period of several years. A comparison to traditional minimum root mean square‐voltage and time‐duration classifications is also included in this study. [ABSTRACT FROM AUTHOR]

In the past few years, grid‐code requirements for grid‐connected photovoltaic power plants have experienced a continuous evolution in different countries to ensure a reliable power system operation as the level of renewable energy penetration increases to high levels. According to several European grid‐codes, PV power plants must be able to ride through specific and severe disturbances without disconnections. Under this new framework, the present study analyses intensive power quality surveys carried out from 2008 to 2011 in three different Spanish PV power plants: a fixed array installation with 4 MW PV power capacity, a PV power plant including dual axis–trackers with 1 MW PV power capacity, and one more fixed array PV power plant with 5 MW PV power capacity. Voltage dips and supply interruptions have been collected, discussing several methods to characterise the monitored disturbances and to compare these events to current Grid‐Code requirements. Furthermore, the time interval around the residual voltage is proposed and defined by the authors as an additional parameter to provide a complete characterisation of the severity of the disturbances. Results from both characterisations of collected data and comparison with current requirements are also included in the study. [ABSTRACT FROM AUTHOR]

Power fluctuations could have a remarkable impact on power system operation and costs, in accordance with the increasing production of wind power worldwide. In systems with weak interconnections, such as Iberian Peninsula Power System, these fluctuations could be a security issue. In order to characterise the worst effects on power systems of wind power fluctuations, most negative wind power ramp rates can be used. In this study, one‐year real data production of 17 wind farms, scattered over Spain, is analysed regarding the geographical smoothing effect on negative wind power ramp rates. Several control strategies are suggested to reduce the resulting aggregated negative ramps. For each strategy, the controlled power is compared with uncontrolled power output, studying the achieved reduction in negative ramps. The results give a comparison of such strategies, regarding energy losses and improvement for power system operation. [ABSTRACT FROM AUTHOR]