5.3 IEEE 118-bus system
Further to analyse the effectiveness of the proposed methodology on a larger network, modified IEEE 118-bus system [40] is considered. The system is modified to have bus-1 as slack bus. A comparative study of the results obtained with the proposed methodology and those obtained with the methodology proposed in [39] is also carried out for the considered system in order to analyse the performance.
The load flow solution for the considered system gives that line-81 (connected between bus-49 and bus-66) is congested. The power flow through the line is 1.036 pu. The line flow sensitivity factor thus evaluated for the congested system is shown in Table 10 from which it can be observed that line-99, line-105 and line-106 (connected between bus-60 and bus-61, bus-63 and bus-64, bus-64 and bus-65 respectively) have high negative values of line flow sensitivity factor as compared to other lines. Therefore these lines have high priority for placement of TCSC in order to mitigate congestion and can also be observed from Fig. 8. Line-99, having the highest negative value of sensitivity factor, is selected for placement of TCSC to manage congestion.
After placing TCSC in line-99, it has been found from optimization algorithm that for optimal setting of TCSC control parameter at 0.2897 pu, the congestion from the system is managed effectively. For this setting of TCSC, the power flow results are shown in Table 11 which illustrates that the power flow in line-81, which was earlier congested, is within its limit.
Table 10 Line flow sensitivity factor of IEEE 118-bus system for congested line-81