Carlos Gallardo

Active power control of a Virtual Power Plant

The present work develops the entire control system to achieve the active power regulation in a detailed model of a small-scale Virtual Power Plant (VPP). Firstly, the proposed VPP topology is exposed. A DC bus has been used for the integration of the different distributed generators and the storage system. Different DC-DC power converters schemes have been employed to fulfill this goal. Later, by means of an Energy Management System strategy who commands a three-leg three-phase inverter having a suitable modulation technique, the control of the demanded active power is performed. The results exhibit successful responses of the system for both, dynamic and steady state.

Optimum location and tuning of PSS devices considering multi-machine criteria and a heuristic optimization algorithm

This work presents a comprehensive methodology for location and tuning of Power System Stabilizers (PSSs) based on multi-machine criteria. This goal is achieved by means of exploiting the benefits of the DIgSILENT PowerFactory software for management of large and complex electric power systems, and the potential of DIgSILENT Programming Language (DPL) that allows combining different application routines, such as: Power Flow, Small Signal Stability, Optimization and tuning of variables in control systems. Thus, a multistage analysis is proposed in order to: i) define several operating scenarios, ii) determine the proper location of the PSS via analysis of participation factors, and iii) estimating the optimal parameters of the selected PSS for reaching a specific system damping. The complete method has been applied to the Ecuadorian Electric Power System, and the results show a satisfactory PSS tuning for achieving the specified system damping. This method can easily be applied to any other power system.

Optimal control of reactive power in an offshore wind farm with HVDC link

This paper presents the optimal management of the reactive power in an offshore wind farm integrated into the main grid trough high voltage direct current (HVDC) with voltage source converters (VSC). The optimization problem is formulated by the definition of the objective function, which is the reduction of active power losses, and the constraints, that clearly determine the feasible solution space. With the defined problem, an optimization algorithm is selected and implemented, which, through the optimal management of reactive power, obtain lower losses in the system formed by the offshore wind power plant with the DC link. To verify the performance of the selected technique, power losses are determined under normal operating conditions by power flow calculations. Then, once the problem is solved, the power losses are again established with the assignments provided by the optimization method. The results of the two operating states will be analyzed for different generation powers.

Optimal location of sliding mode control and power system stabilizers in order to damp electromechanical oscillations using the residue

The purpose of this work is to find the optimal location of sliding mode control and power system stabilizer in order to damp electromechanical oscillations in the power system using the residue method. The proposed control is evaluated performing several simulations on a modified version of the 39-bus New England power grid. A modal analysis is performed at the test system in order to evaluate numerically the effect of the proposed control. The matrices A, B, C and D are exported from the software DigSILENT to the MATLAB simulation software with the purpose to determine the Residue and find the optimal location of a Sliding Mode Control and PSS. The controller is added to the automatic voltage regulator of the select generator.

Sliding-Mode control on DC-DC converters of a virtual power plant

In this work, Sliding-Mode Control (SMC) is employed to control different DC-DC converters in a Photovoltaic-Wind-Battery based Virtual Power Plant (VPP). Firstly, the VPP scheme is detailed. Secondly, a DC-DC converter is employed on every Distributed Generator and Energy Storage System. Moreover, in order to integrate the output power of the DC-DC converters and for feeding a three-phase voltage source inverter synchronized to the distribution network, a DC bus is applied. Thus, the design of the proposed SMC controller is achieved by using space state small-signal average equations from the converters. Likewise, the system performance is analyzed on different scenarios and profiles. Finally, the results are exposed remarking proper dynamic and steady-state responses.