Fig. 5 shows the basic simulation model of the DSTATCOM system. The considered load is a combination of resistance and inductance connected in series for each phase. The load is star connected 32kVA at 0.8pf The DSTATCOM model is simulated with above described p-q theory, SRF theory and Adaline based theory. Figs. 6(a)-(c) show the simulation models for these theories. The model assembled using mathematical blocks of SIMULINK block-set. The simulation is carried out in continuous mode at maximum step size of 1*10-6 with odel5s (stiff/NDF) solver

**Fig. 5 : ***MATLAB based model of DSTATCOM System*

**Fig. 6(b)** – *MATLAB Model of IRP theory
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**Fig. 6(b) :**MATLAB Model of SRF theory

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**Fig. 6 (c) :** MATLAB Model of ADALINE theory

RESULTS AND DISCUSSION

The performance of DSTATCOM is studied for all three methods of control techniques. The following observations are made based on these results.

*A. Control of DSTATCOM by p-q Theory*

Fig. 7 shows the dynamic performance of DSTATCOM using the p-q theory based current extractor. The considered load is reactive at 0.8 lagging power factor. The iref is the real part of the load current. The load has been increased from 16kVA to 32kVA at 0.12sec and unbalanced is introduced at 0.18 sec. After 0.24 sec the dynamics are shown in reverse sequence. The operation of DSTATCOM controlled by the p-q theory is shown in Fig. 8. The dynamics and unbalance conditions are simulated as per the previous case. The delay in compensation can be seen from source current waveforms. This delay is due to the low pass filter (LPF) used for filtering power signals. Moreover, p-q theory uses voltage signals to compute instantaneous active and reactive powers, any distortion and unbalance in voltage will lead to inaccurate calculation of reference source currents which should contain only real fundamental frequency component of load current.