ESQUEMA DE ESTIMACIÓN DE IMPEDANCIA DE RED BASADO EN MÍNIMOS CUADRADOS RECURSIVOS PARA INVERSORES INTERCONECTADOS (GRID IMPEDANCE ESTIMATION SCHEME BASED ON RECURSIVE LEAST SQUARES FOR INTERCONNECTED INVERTERS)
Resumen
La integración de generación distribuida presenta desafíos, como: variaciones de voltaje, deterioro e inestabilidad en la operación del inversor; entre otros, debido a la impedancia de red en el punto de conexión común. Por esto, se propone la estimación pasiva de la impedancia de red, mediante el algoritmo RLS (Recursive Least Squares) y mediciones del voltaje y corriente. La estrategia usa el modelo matemático discreto, que relaciona la corriente y voltajes a través de la impedancia. El algoritmo RLS se diseña y ajusta para estimar los parámetros del modelo, a partir de los cuales se calculan los valores de resistencia e inductancia de red. La naturaleza recursiva del RLS permite detectar cambios en la impedancia de red. La estrategia de estimación se prueba en simulación (Matlab/Simulink) en un inversor trifásico, tanto en condiciones ideales en red como en condiciones de desbalance y contenido armónico, demostrando un buen desempeño.
Palabras Clave: Generación Distribuida, Impedancia de Red, Inversores, Mínimos Cuadrados Recursivos.
Abstract
The grid integration of distributed generation faces challenges, such as: voltage variations, worsening and instability in the inverter operation; among others, due to the grid impedance at the common point of connection. Due to this, grid impedance passive estimation is proposed, based on the Recursive Least Squares (RLS) algorithm and measurements of voltage and current. The strategy uses the discrete mathematical model which relates the current and voltages across the impedance. The RLS algorithm is designed and adjusted to estimate the model parameters, from which the values of resistance and inductance are calculated. The recursive feature of RLS allows also to detect changes in the grid impedance. The estimation strategy is tested in simulation (Matlab/Simulink) in a three-phase inverter, both in ideal conditions in the grid and under unbalances and harmonic distortion conditions, showing a good performance.
Keywords: Distributed Generation, Grid Impedance, Inverters, Recursive Least Squares.
Texto completo:
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