22-09-2012, 09:57 AM
Computer Aided Power System Design and Analysis
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INTRODUCTION
Background
An electric power system is a network of components designed to efficiently transmit and distribute the energy produced by generators to the location where it is used (Chapman, 2002). The network consist of three basic components: the generating plant, the transmission network and the distribution and they have to supply electrical energy, meet the demand of reactive and real power of consumers with a high quality of supply and at statutory ecological requirements and a fair price (Ghanim, 2009).
Comment on the Load Flow analysis and fault level
From Appendix 1, the Grid produces active and reactive power. At busbars BUS-0001 and BUS-0003, active (P) and reactive (Q) powers were produced as a result of the loads while at BUS-0002 no active and reactive power produces because there was no load. I also noticed that there were active and reactive powers produced by the transmission line. Between BUS-0001 and BUS-0003, active power was unchanged while reactive power dropped.
Active and reactive power were produced between BUS-0003 and BUS-0004 by the transformer, line 3 (L3) and by the loads at BUS-0004 and BUS-0005. There were little drop changes in active and reactive power at the primary and secondary winding of the transformer and a significant decrease in the reactive power at BUS-0004 t0 BUS-0005 due to the much difference in load ratings.
The voltage profile was between the statutory limits of ±10% for the high voltage side and -6%, +10% for the low voltage side.
Comparison
The fault current value 17.331 kVA which in software ERACS, it is quite close to the theoretical value 18.099 kVA from the calculation. And this can be accepted, because the network is not the ideal model that there are some losses from the system
Result of system with a VAr compensator
The Load Flow analysis and fault level of the system with a VAr compensator are shown in Appendix 4 while Table 3.3 shows the result of the voltage profile and fault level. Figure 3.3.1 and 3.3.2 shows the voltage profile plot and fault level at different part of the system.
Conclusions, methods of voltage P and Q control
In my scenarios, I used 75% GS (Solar panel) and 25% GI (Wind turbine) considering the location of the network to be in the southern part of the UK where more sunlight can be harnessed. I also changed the dead band settings on the tap changer from 2.5% to 0.5% because it was ‘hunting’. The dead band must not be too wide and is set to a voltage between 2 and 3 tap increments which is usually in the range of 0.5%-1.5% of the nominal secondary voltage in order to avoid hunting and burn up of the tap changer (Nguegan and Yves, 2009 p.79).