Research On Optimizing Allocation And Design Methods For Auxiliary Damping Controllers Of Power Systems

With the growing expansion of power grid, low frequency oscillation problem has become an important aspect of power system stability. The damping of power system has become more and more weak with the regional power sytems interconnections. So the increasing risk of low frequency oscillation brings a serious problem of restricting the inter-regional power exchange and stability of power system. Damoing control is an effective way to solve the problem of low frequency oscillation. At present, Power System Stabilizer (PSS) and Flexible AC Transmission Systems (FACTS) auxiliary damping controller are widely used to suppress low frequency oscillation. Therefore, how to improve the damping level of controller and reduce the controller's interaction are very important and significant from the control strategies and methods, not only for theorerical research but for practical applications.First the allocation method of auxiliary damping controller is studied in this paper. Then the conventional auxiliary damping controllers of power system are coordinated and parameters optimizing design. Finally, the new PSS and FACTS auxiliary damping controller are detailed in two aspects of the design methods and control strategied.The auxiliary damping controller should be adequate from engineering perspective, because adverse interaction will reduce the control performace of controller. Reasonable choice to install auxiliary damping controller will become an important aspect of controller coordination in major regional power system. A new configuration method of auxiliary damping controller based on singular value decomposition (SVD) and model identify is proposed. This method solves the problem of the damping controller allocation. Since both QR decomposition of system state matrix and the calculation of residues on transfer function are not needed, this method can reduce the computational burden. With the solution to the largest singular value and singular vector of system transfer function matrix, the method can identify each generator's contribution to oscillation modes, and then find the optimum allocation of supplementary damping excitation controller. This method laid the foundation for the coordination of the auxiliary damping controllers. Test results show that the method of SVD can find the effective allocation of damping fastly.In this dissertation, the coordination problem of traditional PSS is studied in order to make full use of damping effective in multi-machine power system. First of all, the Particle Swarm Optimization (PSO) algorithm as a variation factor is embedded in Bacterial Forging Optimization (BFO) algorithm, and BFO-PSO hybrid algorithm is proposed, which has the benefits of the strong global search capability of PSO and the good local search ability of BFO. On this basis the new method of coordination of power system damping controller is proposed. The method makes parameter design of damping controller boil down to the goal optimization problem. Through the nonlinear transform the constraint problem transformed unconstrained problem, and then use PSO-BFO hybrid optimization algorithm to design parameter of damping controllers. In order to enhance the system robustness, the method considers varies operation conditions in the objective function. Finally, by calculation analysis the method is verified to be reasonable, and effectively inhibited the low-frequency oscillations.In order to make the control system having good robustness, and ensure the stability of power systems in large-scale operation, the minimum entropy H∞additional excitation controller is proposed. For avoiding the zero-pole cancellation between controller and target by solving the Riccati equation, PS/T sensitivity design method is introduced. For the selection of weighing function, a minimum entropy additional excitation robust damping controller is proposed which transforms different design goals into inequality constraints, and makes the selection of weighing function change as a multi-objective optimization problem. In order to reduce the complexity of the system and increase the practicality of the controller, the optimal Hankel norm reduced-order method is used to deal with the original system and the controller, making a relatively low order controller.In order to regional modal oscillation damping, the auxiliary damping controller design method is studies. First of all, the interaction of voltage control and damping control for SVC is analyzed. On this basis additional damping controller model for SVC is founded, and the fraction rank additional damping controller is proposed. BFO-PSO algorithm is introduced to solving the parameter design of the fractional order controller. And the coordination control objective function is proposed, which can damp system modal oscillations and keeping node voltage stability. So the thesis turns the design of controller into a multi-objective optimization. Finally, by calculation analysis the fraction rank additional damping controller is verified to be effective.