IEEE zyxwvutsrqpo Transactions zyxwvutsrqpon on Power Systems, Vol. 3, zyxwvutsrq No. 1, February 1988 AN INTEGRATED ENGINEERING SIMULATION ENVIRONMENT F. L. Alvarado, Senior Member R. H. Lasseter, Member zyxwvut Y. Liu, Student Member Electrical zyxwvutsrqp IG Computer Engineering The University of Wisconsin-Madison Abstract This paper presents an implementation of a new concept, the Integrated Engineering Simulation Environment (IESE). At the core of the IESE is an object-oriented database system which uses semantic data models and graphics-oriented manipulations. An on-line rule-based expert system i s incorporated t o enforce constraints on connections. Examples of application of the IESE t o Electromagnetic Transient Simulations are presented. The main result of the paper is to establish the generality of this new approach t o engineering software development, and t o show that extremely diverse applications (including graphics interfaces) can be accommodated by simple modifications to database schemata, without reprogramming. I. INTRODUCTION The Electro-Magnetic Transients Program (EMTP) i s one of most sophisticated and widely accepted simulation program in electrical power transients studies. It was originally developed by the Bonneville Power Administration and is currently also under development by EPRI , (Electric Power Research Institute) and an international group of industrial sponsors, collectively known as DCG (Development Coordination Group). The EMTP itself i s reasonably well debugged, efficient, powerful, and flexible. However, the EMTP was f i r s t developed almost 20 years ago when computing was usually done by batch processing using punched cards as input. A main drawback of the EMTP i s its user interface. The user has t o prepare card images as input. This is a tedious job and limits effectiveness and usability of the program. Many efforts have been made t o enhance the EMTP user interface. Lasseter and Liu made initial attempts t o interactively convert input circuit data into EMTP card images [lo]. Electrocon International developed a prototype graphics-assisted interactive interface to t h e EMTP (II/EMTP) [1,2,8]. Recent advances i n both computer hardware and software make it possible t o resolve the interface problem i n a more general and complete way. This paper presents not only a user- friendly interface to the EMTP, but a broader concept: an Integrated Engineering Simulation Environment (IESE). This environment integrates a graphics- oriented interface with a modular engineering database. Using the IESE, an engineer is able to fulfill all engineering design phases: create and layout designs graphically, call a rule-checker for violation of design rules, run various simulation programs to test performance of the design, modify a design, and zyxwvutsrqp so on. This paper was sponsored by the IEEE Power Engineering Society for presentation at the IEEE Power Industry Computer Applica- tion Conference, Montreal, Canada, May 18-21, 1987. Manuscript was published in the zyxwvutsrqpo 1987 PICA Conference Record. 245 The term environment is used to refer to everything i n a computer that a user can directly access and utilize in a unified and coordinated manner. A popular environment i s the menu-driven or mode-driven one. To run a program i n such an environment, the user must enter a certain mode. Within this mode, a menu may be displayed. With each selection out of the menu, the user can perform a function or enter another mode. Some e x p e r t s c r i t i c i z e this mode-driven environment as unfriendly to users [13,15]. A naive user i s often confused with modes: "which mode am I in?" and "How do I get out of this mode?". Even a sophisticated user often enters commands used i n a mode when i n another mode, leading t o undesired and distressing consequences. The most serious shortcoming of the mode-dri ven environment i s that the user cannot use available facilities efficiently. For example, when editing a circuit, the user may want t o call the rule-checker t o see if there is any violation of design rules. This requires exiting the editor mode, storing the circuit in a file, and then invoking the rule-checker. The integrated environment i s preferable. In an integrated environment the user can interweave activities without losing accumulated information and without giving up capabilities of the computer. An example of an integrated environment i s Caesar r131. Caesar i s a CAD (Computer Aided Design) environment f o r VLSI design. Caesar uses a color raster scan monitor, which i s used to display VLSI layout, and a text terminal, which i s used t o enter commands performing specified operations on a database. There are no modes i n Caesar. Every capability of Caesar i s always available t o the user. Within Caesar's environment the user can design VLSI circuits on the graphics terminal, call the rule-checker to verify validity of the design, run simulations to test performance of the design by issuing commands through the text terminal, and then go back t o modify the design. Smalltalk suggests an advanced integrated environment [15]. In the Smalltalk environment, the user can open several windows. Each window can perform a different process. With the aid of a pointing device, the user can pop an obscured window t o the top. The advantages of overlapping windows are: o the displays associated with several processes 0 switching between processes is done by simply zy 0 no information i s lost when switching hetween o can he viewed simultaneously; pushing a button; processes; and screen space i s used economically. The concept of an integrated engineering environment involves several disciplines within computer science, such as database, artificial intelligence, and graphics. By integrating techniques i n these disciplines, with the supports of multiple- overlapping window systems, an integrated engineering simulation environment (IESE) has been developed on the Apollo computer. At the core of the IESE i s an object- oriented database system which uses semantic data models and graphics-oriented manipulations. As an example of applications, the IESE provides a user- friendly and effective interface to the EMTP program. 0885-8950/88/0200-0245$01 .WO1988 IEEE