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This study presents an automatic network balancing technique to limit the capacitive unbalance in resonant grounded power distribution systems (RGPDSs). The aim of this capacitive balancing technique is to minimise the unbalance current through the line to ground (which is the current through the neutral of the system) in order to automatically limit the neutral voltage. The proposed technique is designed by combining the weighted-sum technique and genetic algorithm (GA), where distributed switched capacitor banks (SCBs) are used for balancing RGPDSs. The proposed technique is employed to optimise available SCBs for limiting the network unbalance at the substation under a pre-defined threshold considering all possible network configurations. The unbalances at different locations of the network are also minimised to limit the system unbalance within the threshold due to minor changes in network parameters. Since the lifetime of capacitor banks relies on the switching, the proposed technique is designed in such a way that the system balance is achieved with the minimum switching. The performance of the proposed technique is evaluated through simulation studies in MATLAB/SimpowerSystems environment. Simulation results show that the proposed technique works well and capable to maintain the capacitive balance of the system with changes in network configurations. [ABSTRACT FROM AUTHOR]

Power systems are frequently subjected to variations of the operating conditions due to the occurrence of contingencies such as faults, load or generator tripping. These disturbances might enforce the system to enter the instability region and thus deteriorate its overall performance. This paper proposes a systematic approach for transient stability assessment using generator-based threshold. An individual stability limit is designed for each generator instead of using only one pre-defined threshold for all generators. The considered contingencies are characterized by a fault type, location, loading condition and critical clearing time to consider wide range of operating conditions. Two fault locations are only considered to reduce the search space for stability limits; the generator terminals and mid of transmission lines. The critical clearing time is used to find the maximum relative rotor angle (MRRA) of individual generators attained during the entire time domain simulation. The MRRA of each generator represents the maximum angle which can be reached without losing synchronism at a given contingency. Conservative stability limits are drawn around the minimum stable drift of each generator which is chosen from the set of MRRAs of all contingencies. The effectiveness of the proposed approach is tested using the modified New-England, 39-bus system.