Cascade Tripping of the Power Grid

Cascade tripping is the tripping of power grid in unbalanced condition or it is the tripping of safety devices and isolation of the part of the system to prevent damage to equipment. Cascade tripping occurs during under frequency or other unbalance condition. When demand is more than power generated the frequency of machine goes down. When this frequency is less then certain limit, the grid will trip .This will result in sudden loss of power. If demand is less then generation, it will also cause such situations. Which is also called blackout or grid failure. To avoid this synchronism must be maintained in the grid. Synchronous generators thousands of kilometers apart must operate stably and in synchronism during infinitely many load and power transfer conditions, equipment outages, and power disturbances following a short circuit or other disturbance, one group of generators could accelerate relative to another group, causing instability and loss of synchronism. Implications of blackout are clearly enormous for the electrical power industry. Parts of grid are being stretched to their limits.