Abstract
The integration of distributed generation brings great change to the operation mode of the distribution network, and higher requirements have also been set for the fault recovery scheme. Analysing the relationship between fault reclosing and voltage variation of the distributed generation in distribution network and considering the influence of reclosing on LVRT of DG, this paper proposes a new fault recovery scheme cooperating with reclosing and LVRT (low voltage ride through) for active distribution network. The planned isolated island area is divided in advance for each DG, and different fault recovery methods are implemented according to the different fault conditions of the fault location, the isolated island area and the voltage variation of the distributed generation. The feasibility and effectiveness of the proposed scheme are verified by simulation in PSCAD.
Highlights
If the first voltage drops below 50% of the rated voltage, the second voltage drop will cause the distributed power supply to exit operation due to low voltage ride through failure; if the voltage at the point of common coupling (PCC) drops to more than 50% of the rated voltage, it is considered the first the secondary voltage drop will not cause the low voltage ride through failure
If the fault section is on the downstream side of the DG or on the adjacent feeder, the network topology obtained by the information exchange between the smart terminal unit (STU) at the PCC of the distributed power supply and other STUs on the feeder is used to detect whether each DG still has a complete Plan the island area
Since the fault section is on the downstream side of DG1 and the planned islanding area is complete, if it is detected that the voltage at PCC1 drops to the rated value for the first time If the voltage is below 50%, the switches K3 and K4 are actively disconnected, so that DG1 is islanded as planned, and the switch K5 no longer performs reclosing operation, which effectively saves the fault recovery time
Summary
K1 and K2 trip to isolate the fault, and close to the power side switch K1 to reclose If the fault is a transient fault, the reclosing is successful, the switch K2 is notified to close, the tie switch always maintains the "open" state, and the line resumes normal operation; if a permanent fault occurs, the reclosing fails, and the switch K1 trips again Open, the voltage of bus 1, 3, 4, 5, 6 drops twice. Reclosing may cause the low voltage ride-through failure of distributed power generation, which will cause DG to exit operation and reduce the efficiency of DG power generation This article considers this impact and combines the anti-islanding protection to propose different power supply restoration schemes for different fault situations
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