HVDC Circuit Breakers

Home   |  About  |  Technologies   |  Report Download   |  Contact Us

Technologies > Solid State Breaker Simulation We decided to simulate a solid state circuit breaker using an HVDC model provided by MATLAB. The model represents a point to point VSC based transmission at 230kV. In our attempt to simulate the fault, both cables were connected to a switch, which when opened both cables became grounded. Our breaker consists of an IGBT and a varistor in parallel. The IGBT is used instead of a GCT because that was available from MATLAB and their difference is only on the on state losses. The model is presented below. Figure 7: HVDC MATLAB model At first we tested the power changes when the fault occurred. The fault occurred at 0.3s while the IGBT interrupted at 0.5s. From figure 8 we can see that even though power should be zero, during 0.1-0.3s there are some on state losses due to the use of IGBTs. Furthermore, once the DC fault occurs power increases rapidly, which is normal since current increases until the interruption occurs. Power though continues to oscillate even after the interruption has occurred. Figure 8: Power vs. time graph Then we tested the current response of the model. We modeled the DC fault to occur at 0.3s and turned on the IGBT for current interruption at 0.65s. It is clear that once the fault occurs the current increase is rapid, though the breaker response is immediate and current drops back to its original value. Our simulation showed that solid-state circuit breakers have rather high on-state losses which can be a clear disadvantage. On the other hand, it has a very small interruption time and its functionality at 230kV is very promising. Figure 9: Current vs. Time   <<Prev  Back   Next>>