Estimation of Power System Inertia from Electromechanical Modes

The inertia of many power systems is expected to decrease as more wind and solar power is introduced. With low inertia, a need to estimate it arises. The estimation method should preferably work during normal operation, in order to ensure that the grid frequency can be maintained during any sudden disturbance. This study proposes a new method for inertia estimation, based on electromechanical modes. The method consists of two steps, the first being estimation of modes, which is done from normal frequency variations, and the second being estimation of the inertia from the modes, which is done using a model of the system. The rigid body mode, in which all machines in the system participate, and inter-area and other inter-generator modes are all possible to use. The method was applied to simulated systems with results indicating that it is potentially useful for inertia estimation.