Tossaporn Surinkaew

Coordinated Robust Control of DFIG Wind Turbine and PSS for Stabilization of Power Oscillations Considering System Uncertainties

Uncertainties in power systems, such as intermittent wind power, generating and loading conditions may cause the malfunction of power system stabilizing controllers, which are designed without considering such uncertainties. To enhance the robustness of stabilizing controllers against system uncertainties, this paper proposes a new coordinated robust control of doubly fed induction generator (DFIG) wind turbine equipped with power oscillation damper (POD) and synchronous generator installed with power system stabilizer (PSS) for stabilization of power system oscillations. Without the difficulty of mathematical representation, the inverse output multiplicative perturbation is used to model system uncertainties. The structure of POD and PSS is specified as a practical second-order lead/lag compensator with single input. The parameters optimization of POD and PSS is conducted so that the stabilizing performance and robustness of POD and PSS are augmented. The improved firefly algorithm is applied to solve the optimization problem and achieve the POD and PSS parameters automatically. Simulation study in the modified IEEE-39 bus New England system included with DFIG wind turbines ensures that the robustness and stabilizing performance of the proposed coordinated DFIG with POD and PSS are much superior to those of the conventional DFIG with POD and PSS under various severe disturbances and system uncertainties.

Hierarchical Co-Ordinated Wide Area and Local Controls of DFIG Wind Turbine and PSS for Robust Power Oscillation Damping

In this paper, the two-level hierarchical scheme, which consists of wide area centralized and local controls of the power oscillation damper (POD) installed with the doubly-fed induction generator (DFIG) wind turbine and the power system stabilizer (PSS) has been proposed for robust power oscillation damping. In the wide area level, the centralized POD and PSS has received the input signals from synchronized phasor measurement units (PMUs). The geometric measures of controllability and observability have been applied to select the suitable DFIG and synchronous generator (SG) for stabilizing the target oscillation modes, the proper input signals of the centralized POD and PSS, and the location of PMUs. In the local level, the suitable DFIG and SG have been equipped with POD and PSS, respectively. In the parameters optimization of POD and PSS, the practical issues such as damping performance, controller structure, communication latency, and robustness against system uncertainties have been considered. The controller efficiency and resiliency of the proposed controller have been evaluated in comparison with other controllers by eigenvalue analysis and nonlinear simulation for a wide range of operating conditions, line outage contingencies, severe faults, and communication failure.

Wide area robust centralized power oscillation dampers design for DFIG-based wind turbines

Inter-area oscillations are associated with machines in one part of the system oscillating against machines in other parts of the system. They are caused by two or more groups of machines that are interconnected by weak ties. To damp out the inter-area oscillations, this paper proposes the new application of wide area stability control for robust centralized power oscillation dampers (PODs) design of doubly-fed induction generator (DFIG) wind turbines. The POD with 2nd-order lead/lag compensator structure for each DFIG wind turbine is located at the control center. To stabilize the target inter-area mode effectively, the geometric measures of controllability and observability are used to choose the suitable DFIG wind turbine for stabilizing the target oscillation mode, the proper input signal of POD, and the location of phasor measurement units (PMUs). The input signal of each POD is obtained from PMU while the output signal is transmitted to the rotor side converter voltage controller of DFIG. As a result, the reactive power output of DFIG can be modulated to damp out inter-area oscillations. In the POD parameters optimization, the wide range of power output levels of DFIGs and synchronous generators, time delays due to wide area communication, and unstructured system uncertainties model are taken into account so that the damping of inter-area modes and the system robust stability margin against uncertainties can be guaranteed. Solving the problem by the firefly algorithm automatically, the optimal parameters of PODs can be achieved. The stabilizing performance and robustness of the proposed robust centralized POD are evaluated in the IEEE New England 39 bus system by eigenvalue analyses and nonlinear simulation in scenarios with severe short circuits, N-1 outage contingencies, heavy power flows, and line tripping.

Power System Oscillations Damping by Robust Decentralized DFIG Wind Turbines

This paper proposes a new robust decentralized power oscillation dampers (POD) design of doubly-fed induction generator (DFIG) wind turbine for damping of low frequency electromechanical oscillations in an interconnected power system. The POD structure is based on the practical 2 nd -order lead/lag compensator with single input. Without exact mathematical model, the inverse output multiplicative perturbation is applied to represent system uncertainties such as system parameters variation, various loading conditions etc. The parameters optimization of decentralized PODs is carried out so that the stabilizing performance and robust stability margin against system uncertainties are guaranteed. The improved firefly algorithm is applied to tune the optimal POD parameters automatically. Simulation study in two-area four-machine interconnected system shows that the proposed robust POD is much superior to the conventional POD in terms of stabilizing effect and robustness.

Two-level robust coordinated stabilizing control of PSS and DFIG wind turbine for enhancing grid resiliency

Under the disruption of communication system, the wide area controller may fail to stabilize power oscillations. As a result, the power grids may be jeopardized due to the undamped oscillations. To improve the grid resiliency, a new design method of the two-level robust coordinated stabilizing control of power oscillation damper (POD) of wind turbine with doubly-fed induction generator (DFIG), and power system stabilizer (PSS) is presented in this paper. The two-level control of POD and PSS consists of centralized and local levels. As the main controllers, the centralized POD and PSS are applied to damp out power oscillations. When the communication failure occurs, the local POD and PSS act as the backup controllers to stabilize power oscillations instead of the centralized POD and PSS. The geometric measures of controllability and observability are adopted to determine the suitable input signals of POD and PSS. The structure of POD and PSS is represented by a practical 2nd-order lead/lag compensator. The control parameters of POD and PSS of each control level are separately optimized under various operating conditions so that the damping effect and robustness can be guaranteed. Simulation study is conducted to show the stabilizing effect of the proposed controller on the enhancement of grid resiliency against severe short circuits, line outages, various power flow levels, wind speeds, variable communication latency, and communication failure.