Design of a multilevel inverter with reactive power Control ability for connecting PV cells to the grid

 

ABSTRACT:  

With the increasing use of PV cells in power system, optimal utilization of the equipment is an important issue. In these systems the MPPT controller is used to inject the maximum available power from solar energy. During day time that the active power decreases because of low intensity, the inverter is capable of injecting reactive power up to its nominal capacity and this is a chance for reactive power compensation. In this paper the aim is to propose a control method for injecting the maximum active power and if possible, the reactive power. In addition, a low pass filter is suggested to solve the problem of current fluctuations in case of unbalanced load. Simulation results on a typical system in MATLAB indicate proper performance of the presented method.

KEYWORDS:

 NPC inverter

Maximum Power Point Tracking (MPPT)

Photovoltaic cell (PV)

PI current control

Space vector pulse width modulation (SVPWM)

 SOFTWARE: MATLAB/SIMULINK

 BLOCK DIAGRAM:

 image001

Fig1. Studied system for injecting power to the grid and local load

EXPECTED SIMULATION RESULTS:
image002

Figure2. output active and reactive power of the inverter

image003

Figure3. THD of injected current to the grid in no-load condition

image004

Figure4. Injecting active power in no-load condition and low intensity of light

image005

Figure5. load increase at t=0.5s and its effects on active and reactive power

image006

Figure6. Injected voltage and current to the grid and the effect of inductive load on current

image007

Figure7. Analyzing THD of injected current to the grid in PeL=50kw and PQL=30kvar condition

image008

Figure8. Power increment in two levels: a. at t=0.5s and b. at t=0.7s

image009

Figure9. Output power of inverter and the grid

image010

Figure10. Output voltage and current after using filter and limiter

image011

Figure11. THD of circuit when PeL=50kw and PQL=30kvar and using filter and limiter

CONCLUSION:

In this paper a control strategy is proposed for current control of PV inverter that control s maximum generated active power and reactive power compensation of local load simultaneously .The main idea is to utilize inverter for reactive power injection during active power decrement .using a low pass filter and power limiter in control system , produced oscillations due to unbalanced load is eliminated and inverter works in safe condition simulation results show the proposed method to be viable in controlling inverter

REFERENCES:

[1] Chung-ChuanHou,Chih-Chung Shih, Po-Tai Cheng,Ahmet M. Hava, Common-Mode Voltage Reduction Pulsewidth

Modulation Techniques for Three-Phase Grid-Connected Converters , IEEE TRANSACTIONS ON POWER ELECTRONICS, VOL. 28, NO. 4, APRIL 2013

[2] GeorgiosTsengenes, Thomas Nathenas, Georgios Adamidis,” A three-level space vector modulated grid connected inverter with control scheme based on instantaneous power theory”, Simulation Modelling Practice and Theory 25 (2012) 134–147

[3] S. Kouro, K. Asfaw, R. Goldman, R. Snow, B. Wu, and J. Rodríguez, NPC Multilevel Multistring Topology for Larg Scale Grid Connected Photovoltaic Systems,2010 2nd IEEE International Symposium on Power Electronics for Distributed Generation Systems

[4] Georgios A. Tsengenes, Georgios A. Adamidis, Study of a Simple Control Strategy for Grid

Connected VSI Using SVPWM and p-q Theory,XIX International Conference on Electrical Machines – ICEM 2010, Rome

[5] César Trujillo Rodríguez, David Velasco de la Fuente, Gabriel Garcerá, Emilio Figueres, and Javier A. Gua can eme Moreno,Reconfigurable Control Scheme for a PV

2016-17 IEEE Electrical Projects List

Leave a Reply

Your email address will not be published. Required fields are marked *