Controlled Impedance-Admittance-Torque Nonlinear Modeling and Analysis of Modern Power Systems

Abstract

Modern power systems are continuously transformed into decentralized ones where distributed generation (DG) plays a key role. Almost all the different distributed energy resources (DERs) are connected in geographically dispersed places through controlled power electronic interfaces in a manner that essentially affects the dynamic performance and control of the whole power system. Simultaneously, rotating machines in power production or absorption, dominate the system response and stability. In this new frame, this paper proposes a novel generalized dynamic representation and full scale modeling of a modern power system based on the well-known impedance-admittance (IA) network model for the electricity grid, substantially extended to include in detail both the power converter devices by considering the controlled power electronic dynamics and the electrical machines by inserting their full electromechanical dynamics. This formulation results in a holistic nonlinear dynamic description, defined here as controlled impedance-admittance-torque (CIAT) model of the whole system which features common structural characteristics. The model is deployed in state space, involves all the controlled inputs in DG, namely the duty-ratio signals of each power converter interface, all the other external inputs affecting the system, namely all the known or unknown voltage, current, and torque inputs. As shown in the paper, the proposed CIAT model retains its fundamental properties for any DG and network topology, standard or varying. This enables the compression of the accurate analytic power system dynamic description into a matrix-based generic nonlinear model that can be easily used for analysis studies of such large-scale systems. Taking into account the nonlinear nature of the CIAT matrix-based model and the persistent action of the external inputs, Lyapunov methods deployed on recently established input to state stability (ISS) notions are systematically applied for the system analysis. Hence, the traditionally used small-signal model-based analysis that suffers from the intermittent and continuously changing operation of DERs is completely substituted by the proposed formulation. A modern power system example with different DERs involved is analyzed by this way and is extensively simulated to verify the validity of the proposed method.

Modern Power System Dynamics, Stability and Control

“…A novel generalized dynamic representation and full scale modeling of a modern power system is proposed by Papageorgiou et al in [2]. The developed formulation results in a holistic nonlinear dynamic description, defined here as controlled impedance-admittance-torque (CIAT) model that is extended to include in detail: the well-known impedance-admittance network model, the power converter devices by considering the controlled power electronic dynamics and the electrical machines by inserting their full electromechanical dynamics.…”

Nonlinear Technologies in Advanced Power Systems: Analysis and Control

“…Papageorgiou and other authors in [8] remark the complexity of a power plant system. The distributed generation problem makes the global control strategy a key-point of the correct behavior of the systems.…”

Voltage Regulation and Current Sharing in DC Microgrids With Different Information Scenarios

“…Let W be the Lyapunov function composed of the Lyapunov functions introduced in the previous section. Using (28), (34), (35), (36), (38), W is…”

“…We extend the analysis of a DC microgrid with a single super-capacitor introduced in [4] and [18]. The master-slave distributed nonlinear control technique presented in [4] is modified into a droop-like current sharing one, which is obtained from an ISS Lyapunov function (see [31], [34], [35], [36], [37]) with respect to a reference signal playing the role of a (fictitious) input [38]. The novelty of our results as compared to contributions on current sharing for DC microgrids is the use of a droop-like approach that is closer to well-known control techniques for power systems.…”