Load–frequency control of interconnected power system with governor backlash nonlinearities

In this paper, the stability-equation method is applied to the analysis and design of an interconnected power system with governor backlash nonlinearities. The considered system is a nonlinear multivariable feedback control system. The governor nonlinearities tend to produce a sustaining oscillation in area frequency and tie-line power transient responses. Most conventional linear design techniques are usually unable to find the sustaining oscillation in design phase and need simulation verifications to check the validations after designs. However, the proposed method can consider effects of nonlinearities in the design phase. Some nonlinear design techniques need parameters optimization method by Lyapunov theorem or Integral of Square Errors (ISE) criteria. They are effective. However, they need large computation efforts. The proposed method can choice frequency bias parameters and integrator gains of supplementary controllers for avoiding the oscillation or reducing the amplitude of the oscillation to be acceptable. Simulation verifications show that the proposed method can provide a simple and effective way for the considered system.

► Proposed method can consider effects of governor backlash nonlinearities in the design phase.
► Unstable, limit-cycle and stable regions of the system are found in parameter planes.
► Parameters of controllers are chosen in the parameter plane for reducing amplitude of oscillation.
► Parameters of controllers are chosen in the parameter plane for avoiding sustaining oscillation.