1. Melo EDP PT Session 2 – Block III – Question 9.1 Barcelona 12-15 May 2003 1 EDP Distribuição Energia ASD Immunization to Voltage Dips Case Study in Cement Industry

2. Melo EDP PT Session 2 – Block III – Question 9.1 Barcelona 12-15 May 2003 2 General approach Electric utility side  Protections optimisation  Split busses and load transfer  Close of HV meshes Customer installations side  Implementation of high power quality technologies with energy storage in critical sectors  Immunization of sensible equipment through software and hardware techniques

3. Melo EDP PT Session 2 – Block III – Question 9.1 Barcelona 12-15 May 2003 3 Cement plant characterization Cement plant is supplied in HV (60kV) by two independent feeders Main loads are mills, fans, compressors and pumps The application of ASD in fans presents a large energy saving potential and an excellent improvement of the process flexibility Main fans of the production process are driving by ASD

4. Melo EDP PT Session 2 – Block III – Question 9.1 Barcelona 12-15 May 2003 4 Kinetic energy recovery on fans Tripping of critical fans with voltage dips can cause the whole production process stop We are attending the implementation of KER technique in cement industry This ride-through technique was applied only in ASD that drive critical fans Voltages and power of machines  Voltage: 690V and 400V  Power: 800kW, 216kW, 200kW and 160kW

5. Melo EDP PT Session 2 – Block III – Question 9.1 Barcelona 12-15 May 2003 5 Normal AC Voltage ASD behaviour with voltage dip 100% 50% t1t1 tt2t2 t3t3 t 1 – t 3 : Voltage Dipt 2 – t 3 : Kinetic Energy Recovery DC Voltage Motor Speed AC Voltage

6. Melo EDP PT Session 2 – Block III – Question 9.1 Barcelona 12-15 May 2003 6 Conclusions In the cement plant the voltage dips severity is lower (supplied in HV) Kinetic energy recovery is an easy and fast immunity technique without investment The analysis period after implementation is still reduced but we hope a better operation The ride-through capability improvement should start in critical loads