Full- and Reduced-Order State-Space Modeling of Wind Turbine Systems with Permanent Magnet Synchronous Generator

Abstract

Wind energy is an integral part of nowadays energy supply and one of the fastest growing sources of electricity in the world today. Accurate models for wind energy conversion systems (WECSs) are of key interest for the analysis and control design of present and future energy systems. Existing control-oriented WECSs models are subject to unstructured simplifications, which have not been discussed in literature so far. Thus, this technical note presents are thorough derivation of a physical state-space model for permanent magnet synchronous generator WECSs. The physical model considers all dynamic effects that significantly influence the system's power output, including the switching of the power electronics. Alternatively, the model is formulated in the (a, b, c)-and (d, q)-reference frame. Secondly, a complete control and operation management system for the wind regimes II and III and the transition between the regimes is presented. The control takes practical effects such as input saturation and integral windup into account. Thirdly, by a structured model reduction procedure, two state-space models of WECS with reduced complexity are derived: a non-switching model and a non-switching reduced-order model. The validity of the models is illustrated and compared through a numerical simulation study.

Combining virtual synchronous machine and feedforward torque control for doubly-fed induction machine based wind energy conversion systems

“…The corresponding anti-windup strategy, including the smooth transition between regimes II -III based on [22], and the gain scheduling, taking changes of V /T 1 in ( 6) into account, are out of scope of this paper (details available at the authors).…”

Combining virtual synchronous machine and feedforward torque control for doubly-fed induction machine based wind energy conversion systems

“…IV. In this case, the torque deviates from its reference in (19), required for inertia emulation; but the misalignment also disturbs the reactive power control in (22), degrading the grid voltage support. The reactive power deviation q s,ref − q s is not compensated for in this paper, as the focus is on the grid frequency support based on the active power response.…”

Generic machine identification and maximum efficiency operation of induction machines

“…1): The control law u dq s = u dq s,pi + u dq s,ff ∈ R 2 comprises two parts, namely (i) the PI-controller u dq s,pi ∈ R 2 and (ii) the feed-forward controller u dq s,ff ∈ R 2 (see e.g. [17], [18]). The PI-controller is given by…”