1. Institute of Power Electronics 1 Comparison of Series Hybrid Active Power Filters in Medium Power Application 14.6.2004 Comparison of Series Hybrid Active Power Filter Control Systems in Medium Power Application Juha Turunen, Mika Salo, Heikki Tuusa Tampere University of Technology Institute of Power Electronics Tampere, Finland Presented by Juha Turunen

2. Institute of Power Electronics 2 Comparison of Series Hybrid Active Power Filters in Medium Power Application 14.6.2004 Introduction Current harmonics are the most common problem in the supply network Current harmonics can be reduced by active filter… Parallel connected active filter, Series connected active filter …or by passive filter… LC-shunt circuit, High-pass filter, etc. …or by hybrid filter Combination of active and passive filters Active and passive filters have drawbacks The purpose of the hybrid filters is to overcome these problems that are characteristic of the individual filter type This presentation compares three series hybrid active power filters (SHAPFs)

3. Institute of Power Electronics 3 Comparison of Series Hybrid Active Power Filters in Medium Power Application 14.6.2004 SHAPF Topology I Main Circuit Figure 1: SHAPF topology I

4. Institute of Power Electronics 4 Comparison of Series Hybrid Active Power Filters in Medium Power Application 14.6.2004 SHAPF Topology I Control System Figure 2: Control system

5. Institute of Power Electronics 5 Comparison of Series Hybrid Active Power Filters in Medium Power Application 14.6.2004 SHAPF Topology II Main Circuit Figure 3: SHAPF topology II

6. Institute of Power Electronics 6 Comparison of Series Hybrid Active Power Filters in Medium Power Application 14.6.2004 SHAPF Topology II Control System Figure 4: Control system

7. Institute of Power Electronics 7 Comparison of Series Hybrid Active Power Filters in Medium Power Application 14.6.2004 SHAPF Topology III Main Circuit Figure 5: SHAPF topology III (1)

8. Institute of Power Electronics 8 Comparison of Series Hybrid Active Power Filters in Medium Power Application 14.6.2004 SHAPF Topology III Control System Figure 6: Control system a) Whole system b) Inductance control block (2)

9. Institute of Power Electronics 9 Comparison of Series Hybrid Active Power Filters in Medium Power Application 14.6.2004 Simulations The comparison of presented SHAPF topologies was done using computer simulations with Matlab program The comparison was made in current filtering capability while minimising power rating of active filter bridge Harmonics producing load was 213 kVA 3-phase voltage source diode rectifier The aim in simulations was to maintain supply current THD below 6% while minimising active filter current Figure 7: A-phase load current

10. Institute of Power Electronics 10 Comparison of Series Hybrid Active Power Filters in Medium Power Application 14.6.2004 Simulation Results (1/2) Figure 8: A-phase supply current a) Topology I b) Topology II c) Topology III Table I: Supply current harmonics

11. Institute of Power Electronics 11 Comparison of Series Hybrid Active Power Filters in Medium Power Application 14.6.2004 Simulation Results (2/2) 6% supply current THD could be achieved with two presented topologies by using different coupling transformer transformation ratio Topology I: transformation ratio 2:1 Topology II: 6% current THD could not be achieved Topology III: transformation ratio 4:1 The reason for worse filtering result using SHAPF topology II was dc-link voltage control, also resistances and stray-inductances of the transformer had their influence SHAPF Topology III was the most effective filter Active filter current was smallest in SHAPF topology III Active filter power rating in topology I 63.6% of the load Active filter power rating in topology III 23.6% of the load Control system of SHAPF topology III is rather complicated Implementation of the control system will be time-consuming

12. Institute of Power Electronics 12 Comparison of Series Hybrid Active Power Filters in Medium Power Application 14.6.2004 Conclusions Three different SHAPF topologies were presented These three SHAPF topologies were compared using computer simulations The comparison was made in current filtering capability while minimising power rating of active filter bridge Topology III was found to be most effective with smallest active filter current