“…In these equations ω denotes the grid angular frequency and x represents any of the average variables. The auxiliary terms K a , K b , I L a and I L b are defined by (15)- (18). It is worth noting that, in [17], a single three-phase three-wire inverter was studied.…”
Section: Equations Of the Averaged Modelmentioning
confidence: 99%
“…Note that the current sensors are placed on the inverter side of the LCL filter. Locating the sensors on this side of the inverter improves the robustness of the system instead of placing the sensors on the grid side [18]: In any system represented in the synchronous reference frame, there are coupling terms between the d-and q-axis. The small-signal model presented in Section 2 show the presence of such coupling terms.…”
Section: It Is Obtained (45) Being εIdi the Current Error In The D-cmentioning
This paper presents a control structure for transformerless photovoltaic inverters connected in parallel to manage photovoltaic fields in the MW range. Large photovoltaic farms are usually divided into several photovoltaic fields, each one of them managed by a centralized high power inverter. The current tendency to build up centralized inverters in the MW range is the use of several transformerless inverters connected in parallel, a topology that provokes the appearance of significant zero-sequence circulating currents among inverters. To eliminate this inconvenience, this paper proposes a control structure that avoids the appearance of circulating currents by controlling the zero-sequence component of the inverters. A second contribution of the paper is the development of a model of n parallel-connected inverters. To validate the concept, the proposed control structure has been applied to a photovoltaic field of 2 MW managed by four 500 kW photovoltaic inverters connected in parallel.
“…In these equations ω denotes the grid angular frequency and x represents any of the average variables. The auxiliary terms K a , K b , I L a and I L b are defined by (15)- (18). It is worth noting that, in [17], a single three-phase three-wire inverter was studied.…”
Section: Equations Of the Averaged Modelmentioning
confidence: 99%
“…Note that the current sensors are placed on the inverter side of the LCL filter. Locating the sensors on this side of the inverter improves the robustness of the system instead of placing the sensors on the grid side [18]: In any system represented in the synchronous reference frame, there are coupling terms between the d-and q-axis. The small-signal model presented in Section 2 show the presence of such coupling terms.…”
Section: It Is Obtained (45) Being εIdi the Current Error In The D-cmentioning
This paper presents a control structure for transformerless photovoltaic inverters connected in parallel to manage photovoltaic fields in the MW range. Large photovoltaic farms are usually divided into several photovoltaic fields, each one of them managed by a centralized high power inverter. The current tendency to build up centralized inverters in the MW range is the use of several transformerless inverters connected in parallel, a topology that provokes the appearance of significant zero-sequence circulating currents among inverters. To eliminate this inconvenience, this paper proposes a control structure that avoids the appearance of circulating currents by controlling the zero-sequence component of the inverters. A second contribution of the paper is the development of a model of n parallel-connected inverters. To validate the concept, the proposed control structure has been applied to a photovoltaic field of 2 MW managed by four 500 kW photovoltaic inverters connected in parallel.
“…Cabe destacar que el filtro de tercer orden propuesto presenta una resonancia que debe ser atenuada bien mediante métodos activos [37], [164], [169], o bien mediante métodos pasivos [163], [170]. En el trabajo que nos ocupa, se ha optado por la implementación de métodos pasivos de amortiguamiento de la resonancia, por lo que la resistencia R d se ha añadido al circuito, en serie con el condensador C f .…”
Section: Diseño Del Filtro Lcl De Salidaunclassified
“…En la Figura 5-8 se muestra el circuito equivalente de una de las fases del transformador DY conectado a la red eléctrica, donde L p , R p , L s y R s modelan la inductancia de fugas y las pérdidas en el cobre del bobinado del primario y del secundario respectivamente, mientras que L red y R red modelan la impedancia de una de las fases de la red eléctrica [2], [24], [165], [170]. En la Figura 5-9 se muestra el mismo modelo que en la Figura 5-8, donde las impedancias del secundario y la tensión entre fase y neutro de la red, V red han sido reflejadas al primario.…”
Section: Diseño Del Filtro Lcl De Salidaunclassified
“…La diferencia entre ambas funciones de transferencia radica en el cero complejoconjugado cuya frecuencia de resonancia se describe en (5.17). Este cero compensa en (5.14) la pérdida de fase introducida por el polo, por lo que, desde el punto de vista de la estabilidad del sistema, el control de la corriente i i es preferible frente al control de la corriente i g [170], tal como se mostrará más adelante. …”
Section: Diseño Del Filtro Lcl De Salidaunclassified
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