A New Technique Implemented in Synchronous Reference Frame for DVR Control Under Severe Sag and Swell Conditions

Abstract

Nowadays, power quality under the excessive implementation of power electronics devices is quite challenging issue. The compensation of non-sinusoidal; reactive and harmonic; components is the main role for power quality devices which highly depend on the robustness of the control system. Some common control systems are implemented using Synchronous Stationary Frame (DQ) theory. This paper proposes a new version of DQ control technique to control dynamic voltage restorer under severe transient voltage conditions. The power system network with the new DQ control technique is studied and analyzed under different scenarios to compensate for severe balanced and unbalanced voltage sags and swells. This new scheme is based on extraction of positive sequence components to implement the control algorithm. A mathematical model of the dynamic voltage restorer (DVR), hysteresis voltage control, converter controller model, new DQ scheme with complete system equations are carried out and verified using Simulink / MATLAB. The proposed system is validated experimentally using D Space 1104 based laboratory system. The obtained results of the proposed compensation algorithm are compared with the results obtained from the traditional DQ method. Simulation and experimental results are correlated and show effectiveness of the proposed DQ control scheme.

Index Terms

Balance and unbalanced load, dynamic voltage restorer (DVR), instantaneous space vector, synchronous stationary frame (DQ) theory, voltage sag, voltage swell.

Circuit diagram:

 

 Figure 1. Basic Circuit Of Power System With DVR.

Expected Simulation Results:

 

Figure 2. Simulation Results Of Grid Voltages, Load Voltage And DVR Voltages (Traditional DQ) Under Balanced 3' Grid Voltage Sag Of 20%.

 

 

Figure 3. Simulation Results Of Grid Voltages, Load Voltage And Dvr Voltages (Modified Dq) Under Balanced 3' Grid Voltage Sag Of 20%.

 Figure 4. Simulation Results Of Grid Voltages, Load Voltage And Dvr Voltages (Traditional Dq) Under Balanced 3' Grid Voltage Swell Of 70%.

 

 Figure 5. Simulation Results Of Grid Voltages, Load Voltage And Dvr Voltages (Modified Dq) Under Balanced 3' Grid Voltage Swell Of 70%.

 

 

Figure 6. Simulation Results Of Grid Voltages, Load Voltage And Dvr Voltages (Traditional Dq) Under Unbalanced 3' Grid Voltage Sag Of 20%.

 

Figure 7. Simulation Results Of Grid Voltages, Load Voltage And Dvr Voltages (Modified Dq) Under Unbalanced 3' Grid Voltage Sag Of 20%.

 

Figure 8. Simulation Results Of Grid Voltages, Load Voltage And Dvr Voltages (Traditional Dq) Under Unbalanced 3' Grid Voltage Swell Of 70%.

 Figure 9. Simulation Results Of Grid Voltages, Load Voltage And Dvr Voltages (Modified Dq) Under Unbalanced 3' Grid Voltage Swell Of 70%.

 

Conclusion

This paper inspects the control of DVR with modified DQ algorithm to generate reference voltage signals to control the DVR. The proposed DVR control method relies on a modified version of DQ theory with a detection method for the positive and negative sequence components. The modelled simulations are carried out in MATLAB Simulink and the results were validated with Experimental setup carried out on DSPACE 1104 module. The results are shown good correlation between simulation and experimental results. The control of modified DQ method is compared with the traditional DQ control technique under the conditions of severe sag and swell. The performance of the controllers is also compared during balanced and unbalanced situation with severe cases of sag and swell. The comparative results suggest that the new modified DQ control method shows effective in compensating voltage during severe sag swell in balance and unbalance conditions with advantages of

· Less computational effort.

· Faster response.

· Less transient oscillation in the fundamental frequency under unbalanced voltage sag and swell.

References

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