Model-based Design Tool for Cyber-physical Power Systems using SystemC-AMS

TL;DR

A model-based design tool for simulating cyber-physical power systems, including microgrids, using SystemC-AMS is presented and it is observed that SystemC-AMS can accurately produce the electromagnetic transient responses essential for analyzing grid stability.

Abstract

Cyber-physical power systems, such as grids, integrate computational and communication components with physical systems to introduce novel functions and improve resilience and fault tolerance. These systems employ computational components and real-time controllers to meet power demands. Microgrids, comprising interconnected components, energy resources within defined electrical boundaries, computational elements, and controllers, offer a solution for integrating renewable energy sources and ensuring resilience in electricity demand. Simulating these cyber-physical systems (CPS) is vital for grid design, as it facilitates the modeling and control of both continuous physical processes and discrete-time power converters and controllers. This paper presents a model-based design tool for simulating cyber-physical power systems, including microgrids, using SystemC-AMS. The adoption of SystemC-AMS enables physical modeling with both native components from the SystemC-AMS library and user-defined computational elements. We observe that SystemC-AMS can accurately produce the electromagnetic transient responses essential for analyzing grid stability. Additionally, we demonstrate the effectiveness of SystemC-AMS through use cases that simulate grid-following inverters. Comparing the SystemC-AMS implementation to one in Simulink reveals that SystemC-AMS offers a more rapid simulation. A design tool like this could support microgrid designers in making informed decisions about the selection of microgrid components prior to installation and deployment.

Figures (8)

• Figure 1: A circuit schematic illustrating a physical model using ELN MoC. The voltage source receives a discrete-time signal as an input from a TDF block. We measure the output as the voltage across the capacitor $C1$ using another ELN primitive voltage sink which acts as a voltmeter. Input and output ports are shown as elongated pentagonal boxes, labeled IN and OUT. The overall circuit with input/output ports can be abstracted as shown in Figure \ref{['fig:EMCircuit_Block']}.
• Figure 2: An abstraction of Figure \ref{['fig:ELN_Circuit']} that can be reused as a subsystem.
• Figure 3: EMT phenomenon observed in the voltage measured across Capacitor bank $C_1$ from the circuit in Figure \ref{['fig:ELN_Circuit']} when simulated in SystemC-AMS with the time-step of $20~\textrm{ns}$. The transient eventually disappears at around $0.35~\textrm{s}$ (not shown in the figure), and the voltage across the capacity $C_1$ stabilizes.
• Figure 4: EMT phenomenon observed in the voltage measured across Capacitor bank $C_1$from the circuit \ref{['fig:ELN_Circuit']} when simulated in SystemC-AMS with several different time-step values. Simulation with a large time step fails to produce an EMT phenomenon while a simulation with a time step smaller than the time period of the natural frequency exhibits an EMT phenomenon.
• Figure 5: Simplified GFL inverter without inner current loops. To break the algebraic loop that arises due to feedback, we use a delay unit $z^{-1}$ which introduces the port delay by one sample at the respective output port. LPF stands for low-pass filter. The GFL inverter model is abstracted as PV-GFL and works with the main grid as shown in Figure \ref{['fig:Microgrid_architecture']}. abc 2 dq0 block is a TDF module that converts a time-varying three-phase signal to a dq0 reference frame (where signals appear to have a constant phase). dq0 2 abc does the opposite job. A PI block is a discrete-time controller implemented using TDF MoC with a sampling frequency of $1000~\textrm{Hz}$. We can specify active power reference and reactive power reference for the simulation as time-domain functions which are implemented using TDF MoC.