Modeling Environment Research Articles

Modeling Environment for Testing a Distributed Energy Resource Management System (DERMS) Using GridAPPS-D Platform

The electric power system is currently undergoing a major transition due to growing numbers of distributed energy resources (DERs) and increased distribution automation. If optimally managed and operated, DERs could provide flexibility and highly valuable grid services such as restoration, peak shaving, voltage regulation, and frequency support to maintain grid reliability. Different applications and enterprises, such as distributed energy resources management systems (DERMS), are being developed for coordinated and optimal operation of DERs. However, to attract sufficient DER participation and achieve the coordinated operation of DERs, systems and components must be interoperable and information exchange must be secure. Along this line, the Portland State University power engineering group is developing Energy Grid of Things (EGoT) DERMS prototype. The proposed application requires the coordinated dispatch of large numbers of DERs and testing such a system presents a challenge; it is not practical to test system prototypes using thousands of real DERs. Hence, the modeling environment (ME) is designed as a co-simulation tool to model interactions between a DERMS and a mass of simulated DERs. The ME is expected to address the scalability issue inherent to hardware-in-the-loop DERMS simulation; many assets are needed to observe effects on the grid from deployment and dispatch of DERs. To enable the development and testing of such advanced applications for power distribution system planning and operations, the U.S Department of Energy developed GridAPPS-D™, an open-source, standards-based platform at Pacific Northwest National Laboratory. This paper introduces the proposed ME for testing a DERMS application. The architecture of the ME is presented, and the GridAPPS-D features for a such simulation environment are discussed. Additionally, the procedure for developing the ME within the GridAPPS-D platform and use of different APIs for efficient and timely integration are discussed in detail.

Modeling environment for model predictive control of buildings

Model predictive control (MPC) is an advanced control that can be used for dynamic optimization of HVAC equipment. Although the benefits of this technology have been shown in numerous research papers, currently there is no commercially or publicly available software that allows the analysis of building systems that employ MPC. The lack of detailed and robust tools is preventing more accurate analysis of this technology and the identification of factors that influence its energy saving potential. The modeling environment (ME) presented here is a simulation tool for buildings that employ MPC. It enables a systematic study of primary factors influencing dynamic controls and the savings potential for a given building. The ME is highly modular to enable easy future expansion, and sufficiently fast and robust for implementation in a real building. It uses two commercially available computer programs, with no need for source code modifications or complex connections between programs. A simplified building model is used during the optimization, whereas a more complex building model is used after the optimization. It is shown that a simplified building model can adequately replace a more complex model, resulting in significantly shorter computational times for optimization than those found in the literature.

Generation of Advanced Modelling Environments by Means of Graph Transformation Techniques

In this paper we show our approach to the automatic generation of modelling environments for Visual Languages (VLs) supporting multiple views. The approach is based on the meta-modelling tool AToM3. Starting from a meta-model description of the VL and its views, a customized modelling environment is generated. Consistency between views is supported by the automatic generation of triple graph grammar rules that build a unique model “gluing” all the view models. Moreover, the generated environments allow taking basic static metrics of the models. Extreme values of the metrics may trigger heuristics for the refactoring of the models. These heuristics are formalized in the form of graph grammar rules. We show the application of these concepts in the area of hypermedia design by generating an environment for the Labyrinth VL.

Design and Simulation of Heterogeneous Control Systems using Ptolemy II

ABSTRACT Complex control systems are heterogeneous from both an implementation and a modeling perspective. Design and simulation environments for such systems need to integrate different component interaction styles, like differential equations, discrete events, state machines, dataflow networks, and real-time scheduling. This paper motivates the use of Ptolemy II software environment for mode ling and simulation of heterogeneous control systems. Ptolemy II advocates a component-based design methodology, and hierarchically integrates multiple models of computation, which can be used to capture different design perspectives. A Furuta pendulum control system is used as a motivating example. After designing a three-mode hybrid controller under idealized assumptions, implementation effects, like real-time scheduling and network protocols, are taken into consideration to achieve a more realistic simulation. The 3D animation package in Ptolemy II helps designers to visualize the control results. In this process of refining the design, components modeled in early phases can be reused.

A Hydrodynamical Model of Shear Flow over Semi-Infinite Barriers with Application to Density Currents

Abstract Vertically sheared airflow over semi-infinite barriers is investigated with a simple hydrodynamical model. The idealized flow is steady, two-dimensional, neutrally buoyant, and inviscid, bounded on the bottom by a semi-infinite impermeable barrier and on the top by a rigid tropopause lid. With attention further restricted to an exponentially decreasing wind shear, the equations of motion (Euler's equations) reduce, without approximation, to a modified Poisson equation for a pseudo streamfunction and a formula for the Exner function. The free parameters characterizing the model's environment are the tropopause height, the density scale height, the wind speed at ground level, and the wind speed at tropopause level. Additional parameters characterize the barrier geometry. Exact solutions of the equations of motion are obtained for semi-infinite plateau barriers and for a barrier qualitatively resembling the shallow density current associated with some thunderstorm outflows. These solutions are notew...