شبیه ساز آنالوگ قابل کنترل برای تجزیه و تحلیل سیستم قدرت

This paper details the development of a controllable analog emulator for power system analysis. The emulator consists of reconfigurable analog hardware for power system emulation and a digital computer, along with associated software, for configuration, control, calibration and data acquisition. The analog hardware is fully controllable via the software interface. System parameters, initial conditions, integration, faults and contingencies can be created or altered via the software with no changes or manual intervention to the analog hardware. This advance overcomes one of the larger drawbacks of older analog computers, which was the need for manual configuration and calibration. The emulation methodology is presented in this paper as well as power system modeling, both theoretical and in analog hardware. The software interface and control is also presented. To validate the operation of the emulator two examples are shown from a prototype emulator. The first being a steady state power flow solution, the second computes the critical clearing time of a generator fault for transient stability.

With current technology the computation of large power systems is time intensive. There are numerous analog and digital computation methods currently utilized but they fail to meet the growing computational demands of power systems, particularly in system operations. For example, transient stability is a continued field of research [1], [2] and [3] with much focus on faster, more efficient calculation techniques. The power grid is expanding which is increasing the necessity and complexity of contingency studies. Current techniques often rank [4] contingencies and only perform analysis on a subset of the scenarios assumed to be more dangerous. Faster calculation techniques will allow for more thorough contingency analyses. Economic analyses are also demanding a tremendous computational burden. Traditional digital methods are too slow to solve the aforementioned demands quickly at a reasonable cost. Cluster and parallel computing techniques have been proposed [5] and [6] but the cost increases exponentially with the size of the system and the increase in computation performance does not increase at this same rate. Conversely, existing analog simulators can easily simulate the power system in real time but consist of many analog components and require manual intervention to setup and configure the system for each calculation. A controllable real-time computation tool, or faster than real-time, is preferable. Currently, digital simulation is the prevalent method for several reasons. These include (i) the emergence of personal computers (PC) has made this technology reliable and easy to operate, (ii) advances in very large scale integration (VLSI) technology have allowed the development of new parallel computers with performance comparable to that of supercomputers at a fraction of the cost, and (iii) the highly programmable nature of digital computers. In digital simulation the set of algebraic expressions, which describe power system behavior, are discretized and software algorithms (such as Newton–Raphson) utilize input parameters to calculate the steady-state solution. Presently for large-scale systems, studies are performed with several types of massively parallel computers [7], [8], [9], [10], [11] and [12]. The use of digital simulation analysis is seriously inhibited by lengthy computational times inherent to the iterative algorithms they employ and the large cost of hardware and operating costs of massively parallel digital computers. New technological developments have facilitated research in the further development of analog computational tools to achieve fast computations at lower cost. A new approach has been proposed as to how analog technology may be utilized to perform analysis for large power systems [13] and [14]. In addition, recent work has developed general purpose analog processor for use in conjunction with a digital computers [15] to improve computational performance. The main advantage of analog computers is their shorter computational time. In this work, through the use of reconfigurable analog tools such as operational transconductance amplifiers (OTAs), accompanying circuit models for power system components such as generators [16], transmission lines [17], loads [18], and control and data acquisition circuitry and software, a fully controllable analog emulator for power system analysis has been developed. This emulator is suitable for transient and steady-state power system analysis. Example applications for this tool would be transient stability and contingency analysis. The next section of this paper provides an overview of the DC emulation methodology utilized in this power system emulator. Following this, details of the power system emulator are presented. An overview is then provided on the power system models in the DC emulation environment. In addition, the associated analog hardware realizations of these models are shown. Next, a summary of the data acquisition, control and calibration of the hardware is presented along with the software interface to the emulator. This is followed by the presentation of a couple examples, discussion and conclusion.

This paper provided details of a controllable analog emulator for power system analysis. It included the emulation methodology, theoretical and analog circuit models of the power system, along with operation of the emulator. A prototype has been developed and examples have been presented which verify the functionality and accuracy of the emulator for power flow and transient stability analyses. With the use of new technology many shortcomings of traditional analog computers have been addressed by this work. Configuration, calibration, data acquisition and control are all automated via a software interface to the analog emulator. Development is underway to further refine the power system model and software interface for this analog power system emulator.