Multi-domain Co-simulation of Smart Grid: Electrical, Communication, and Distributed Computing

智能電網的多域協同仿真:電氣、通訊、與分佈運算

Student thesis: Doctoral Thesis

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Award date6 Aug 2018

Abstract

The future power system, known as the smart grid, is depicted as the convergence of power engineering, communication, and computing technologies, to allow pervasive monitoring and control over all aspects of the energy system. Smart grids are expected to enable new functionalities in energy systems, e.g., accommodating renewable generations, coordinating of electrical vehicles fleets, and self-healing.

To study these new smart grid applications, performance evaluation and verification are necessary. Unfortunately, real-world platforms are rarely available for the purpose of experimentation due to the costs and the critical nature of power stability. Therefore, most published results are obtained via software-based simulation. For a comprehensive simulation of smart grid, all three aspects of electrical, communication and distributed computation, as well as their inter-dependencies should be modeled. Given the complexity and heterogeneity of the smart grids, creating a comprehensive simulator from scratch would be costly and time consuming. Therefore, the co-simulation approaches are often adopted to combine well-developed and validated domain-specific simulators, e.g. power system and communication network simulators. Each simulator is responsible for modeling and simulating one domain of the smart grid.

However, recent development of smart grid co-simulation platforms have not been able to provide effective support for the modeling and simulation of distributed computing systems. In particular, co-simulation literatures only focused on the integration of electrical and communication network simulators, and the responsibility for modeling distributed software is often delegated to one of these two simulators. Since these domain specific simulators are not designed for this purpose, such delegation incurs many limitations that prevent convenient, effective, and accurate modeling of software behaviors. To mitigate the problem, this thesis presents, to our knowledge, the first co-simulation platform that integrates direct-execution simulators to provide dedicated modeling support for distributed smart grid software.

This thesis first present the development of the novel DecompositionJ framework (DEterministic, COncurrent Multi-PrOcessing SImulaTION for Java programs), which is a compiler-based code analyzer and transformer to automatically convert multi-thread Java programs into direct-execution simulators, to eliminate the need for manual code or model development. Note that the DecompositionJ framework contributes not only to smart grid co-simulation research, but also to direct execution simulation literature. In contrast to other works, DecompositionJ framework can simultaneously provide the following features: i) a simulation model that formally defines the actions of simulated programs, and guarantees to generate deterministic and repeatable results for data-race-free programs; ii) the model accounts for multi-processor execution, consumption of processor time, thread scheduling, and context switching delays; iii) the simulator itself can exploit the multi-core parallelism offered by the host computer; iv) the framework does not require new language features or annotation, therefore the resultant simulators are compatible with conventional development tools, e.g. IDE, debuggers, and profilers.

Next, this thesis present the design of a co-simulation platform, which combines the DecompositionJ simulators with power system transient simulator PSCAD/ EMTDC and packet level network simulator OPNET. The proposed platform adheres to the High Level Architecture (IEEE-1516, HLA) standard, which is the de facto standard for distributed simulation. By adhering to HLA, the proposed platform is highly extensible and inter-operable, such that new simulation tools can be easily integrated to satisfy future needs.

Lastly, to demonstrate the usefulness of the proposed frameworks, a case study on agent-based fault location, isolation and service restoration (FLISR) is presented. In this case study, a popular multi-agent platform JADE is simulated using the DecompositionJ framework, and co-simulation is conducted using the proposed platform. Simulation results illustrate the benefits of using direct-execution technique for modeling and simulating smart grid software. Detailed and authentic software behavior can be generated, and the inter-dependencies between different domains are captured. It is believed that the proposed frameworks is beneficial to the study of a wide range of smart grid applications.