**6. Conclusion**

A new hybrid modulation algorithm to control NP voltage has been described, even under high voltage asymmetries in the DC-bus.

It has been simulated both in symmetric and asymmetric power supplies, achieving voltage and ripple in the NP under control.

This algorithm is ideal for use in photovoltaic panel power source applications, as it tolerates high imbalances. If two independent panel arrays get connected, during cloudy days asymmetries will certainly occur. Nevertheless, each capacitor voltage can be controlled independently, greatly improving global performance of the panels.

Something else to keep in mind with photovoltaic panels is that fixing a capacitor voltage is a quick process, faster than the DC-bus time constant. This is one of the parameters that has the most influence on the changes in MPPT response under rapid perturbations from the environment. Furthermore, a reduction of one capacitor does not necessarily reduce DC-bus voltage; but reducing the degradation of the quality of injected energy in to grid by the fact that MPPT fixes the capacitor reference voltage. Moreover, this algorithm creates a new line of investigation for the design of faster MPPTs and faster responses for better THD.

The proposed algorithm has been validated with simulations shown in this document.

#### **7. Acknowledgment**

This work has been funded by the Spanish Ministry of Science and Education with reference number ENE2008-06588-C04-01.

#### **8. References**

Bueno, E. (2005). *Optimización del comportamiento de un convertidor de tres niveles NPC conectado a la red eléctrica*. Ph.D. thesis, Department of Electronics, University of Alcalá. http://www.depeca.uah.es/

*PV V PV V P D P D* 

Now, the maximum imbalance condition can be given, guaranteeing functionality of the

(1 ) 8

Taking into account that VL is considered constant, maximum asymmetry is fixed by DCbus voltage, which is typically variable when coming from photovoltaic panels. Therefore, the system will work at its maximum performance as long as maximum asymmetry is met. As a solution for higher asymmetries than the maximum asymmetry, the DC-bus voltage can be increased, although when this happens, it moves output away from the maximum

A new hybrid modulation algorithm to control NP voltage has been described, even under

It has been simulated both in symmetric and asymmetric power supplies, achieving voltage

This algorithm is ideal for use in photovoltaic panel power source applications, as it tolerates high imbalances. If two independent panel arrays get connected, during cloudy days asymmetries will certainly occur. Nevertheless, each capacitor voltage can be

Something else to keep in mind with photovoltaic panels is that fixing a capacitor voltage is a quick process, faster than the DC-bus time constant. This is one of the parameters that has the most influence on the changes in MPPT response under rapid perturbations from the environment. Furthermore, a reduction of one capacitor does not necessarily reduce DC-bus voltage; but reducing the degradation of the quality of injected energy in to grid by the fact that MPPT fixes the capacitor reference voltage. Moreover, this algorithm creates a new line

This work has been funded by the Spanish Ministry of Science and Education with reference

Bueno, E. (2005). *Optimización del comportamiento de un convertidor de tres niveles NPC* 

*conectado a la red eléctrica*. Ph.D. thesis, Department of Electronics, University of

controlled independently, greatly improving global performance of the panels.

of investigation for the design of faster MPPTs and faster responses for better THD. The proposed algorithm has been validated with simulations shown in this document.

*D U Umb*

(1 ) (1 )

*V DC*

*D V U*

*V L DC*

(15)

(16)

 min max

*Max*

From (12), (13) and (14):

power point of the panels.

**7. Acknowledgment** 

**8. References** 

number ENE2008-06588-C04-01.

Alcalá. http://www.depeca.uah.es/

high voltage asymmetries in the DC-bus.

and ripple in the NP under control.

**6. Conclusion** 

algorithm. From (11), (12), (13), (14) and (15):

(1 )

