DYNAMIC SECURITY ASSESSMENT SOFTWARE DSATools 转自： http://www.powertechlabs.com/software-modeling/dynamic-security-assessment-software/ DSATools PowerFlow Short Circuit Assessment Tool Voltage Security Assessment Tool Transient Security Assessment Tool Small Signal Analysis Tool WSAT Case Study On-Line Application of DSATools Power System Security
这几天在 Power Globe 上看到对无功功率的一些讨论，把一些比较好的解释放到这里。正如Charles A. Gross 所说，这些解释都（部分地）正确地揭示或说明了无功功率，但也都不是一个完美或根本的解释，其中的一个原因是我们在尝试为一个非物理或抽象的量提供物理解释。 It’s been fun reading all the explanations. One of my favorites is “Q is the foam on the beer…”.They all have elements of truth, but never the whole truth and nothing but the truth. Hence, none really explain what Q is.The reason that we are having so much trouble coming up with a physical explanation for Q is that Q is non-physical, as are many concepts in engineering. --Charles A. Gross, PE, PhD, FIEEE Reactive power is a measure of the back and forth flow between energy in magnetic and electric fields in components. The reactive power value measures the magnitude of the instantaneous flow between these fields. ---B.Ross ------------------------------------------------------------------------------------------------------------- The answer to your question requires some understanding of ac circuits. Ac voltages (V) and currents(I) vary sinusoidally in time and have three basic properties: strength (RMS magnitude, V in volts, I in amperes); frequency (e.g. 60 Hz); and phase. Phase involves two quantities (V and I, in this case) . V and I are said to be “in phase”, if they both peak at the same instant; are zero at the same instant; reverse polarity/direction at same instant; etc. V and I are said to be “out of phase”, if when V peaks, I is zero, and vice versa. More precisely we really should say “V and I are 90 degrees out of phase”. . Now general, V and I are not in phase or 90 degrees out of phase but somewhere in between. It is possible to divide the current (I) into two components: the in-phase component or “active current” (IA) and the (90 deg) out-of-phase component or “reactive current” (IR) Correspondingly, there are two kinds of power: Active Power (P) = V*IA, which we say is measured in watts Reactive Power (Q) = V*IR, which we say is measured in volt-amperes reactive, or “vars” There is also a third kind of power in ac circuits: Apparent Power (S) = V*I, which we say is measured in volt-amperes , or “VA”. These three are related: S = sqrt as are the currents. I = sqrt How much of “I” is “IA” is communicated thru something called the power factor (pf), such that IA = I*pf and P = S*pf An Example: A 120 V ac source supplies 10 A at a pf = 0.8 lagging. The term lagging means that the current trails the voltage in time. Find S, P, and Q. S = V*I = 120(10) = 1200 VA P = S*pf = 1200(0.8) = 960 W Q= sqrt(1200^2-960^2)= 720 var I = 10 A IA = I*pf = 10(0.8) = 8 A IR = sqrt(10^2-80^2)= 6 A Now that we know what Q is, at least in terms of V, I, and phase, what is it physically? There are three passive circuit elements: R,L,C R, and only R, dissipates active power (P). L and C are called “reactive elements” in that they do not dissipate energy, but they do store it an internal magnetic field (L), or electric field (C). This field energy” is constantly flowing into and out of L and C and the source, and over an ac cycle, averages to zero. This energy exchange requires a current component that is necessarily 90 deg out of phase with the voltage (IR), and hence a corresponding power component Q = V*IR. --- Charles A. Gross, PE, PhD, FIEEE ---------------------------------------------------------------------------------------------------------------------------------------------------- Reactive power is a myth and a delusion. It is no more than a mathematical coincidence. It can be extremely useful, but it is without foundation. You know the math: it is just a matter of using a sine or a cosine term to switch between real and reactive power. It is just the difference between the one side or the other of a right-angle triangle. But think! That right triangle does not represent a phasor. The 90-degree rotation business of phasors does not apply because power is not a phasor. A few years ago, NIST did a survey of the way this thing called reactive power was being measured, and found there were at least nine different methods that would give nine different results, depending on how far the waveform was from sinusoidal. It became a NEMA report: NEMA C12.24 TR-2011, Definitions for Calculations of VA, VAh, VAR, and VARh for Poly-Phase Electricity Meters, registered with ANSI May 2011. Over a hundred years ago, we engineers were asking whether it was possible to measure something that was not real, and whether the fact that you could measure something meant that it was real. The digital revolution in measurements has firmly answered that it is possible to measure something that is not real, because the number-crunching part of measurement is no more than data compression. The ways we measure reactive power underlines that. Today, you can buy equipment that will let you choose whose definition you use in the measurement. That is not to say the idea of reactive power is not useful. It has simplified thinking about voltage management in the power system. It has led to some interesting solutions in that area: SVCs for example. But once you get away from the simplified notion of a perfect sine-wave, you enter undefined territory, the realm of imagination. Power factor is in the same boat. Another calculation of very great value and usefulness, and yet not defined for waves that are not sinusoidal. We will, of course, continue to use these terms: they are much too useful to abandon. But we should be aware of their limited meaning, and sometimes we are not. See, for example, Berrisford, A.J., “Smart Meters should be smarter”, presented at the IEEE PES General Meeting, San Diego, CA July 2012. DOI 10.1109/PESGM.2012.6345146 --- Harold Kirkham,Staff Scientist,Pacific Northwest National Laboratory.
--In view of an ongoing trend that more and more new reserachers/facuties from other fields, e.g., cyber security, physics, are entering into the power engineering fields, partly because of the development of the smart grid , I write this brief introduction. It can be helpful, I think, for new ( in terms of power sytem) researcheres to get to know some open software for power system analysis, to better understand some basic stuffs of power systems, and to use a suitable tool in their researches. The following are some of the most commonly-used power sytem open software or toolbox, featuring different application domains and/or programming languages. · PSAT--Matlab This is the first open source project that I got to know when I was a undergraduate student back in 2007. It is not exaggerating to say that it has been the most popular Matlab-based power system toolbox, since it provides almost all common power system analysis algorithms, ranging from load flow to short circuit analysis, to transient stability analysis. Comomly used power system equipment models have also been developed. Further, its broad usage and big user community ( http://tech.groups.yahoo.com/group/psatforum/ ) help it grow and mature. The latest version is 2.1.8. For details: http://www3.uclm.es/profesorado/federico.milano/psat.htm · Matpower—Matlab It is specially designed for power market and optimization related application in power systems.Of course, common Aclf and Dclf algorithms are also provided. Based on my usage ( not much), the code is easy to followed and modified. For details: http://www.pserc.cornell.edu/matpower/ · InterPSS—Java InterPSS (Internet technology based PowerSystem Simulator) is a free and open software development project. Itwas first initiated and developed Dr. Mike Zhou back in 2006. I have been a developer member since August 2008. What makes it different from the other software/toolbox is that it employs modern software architecture idea and OOP programming, dependence injection techniques , etc., enabling it to have an open and loosely coupled system architecture, thus it is designed and developed for integration and extension right from the very beginning, from architecture to algorithm. Features: User-friendly API for power system network data processing at bus/branch and network level. ACLFAnalysis DCLF and sensitivity analysis AC/DC LF based contingency analysis Short circuit analysis Transient stability analysis Optimization—Integration with GAMS High performance computing: Grid computing, Multithreading-based parallel computing Cloud-based power system analysis: InterPSS 2.0 For details: http://www.interpss.org/ · Pypower—Python, SciPy PYPOWER is a power flow and optimal power flow (OPF) solver. Current features include: DC and AC (Newton’s method Fast Decoupled) power flow and DC and AC optimal power flow (OPF) PYPOWER is a translation of MATPOWER to the Python programming language using SciPy . · MinPower —Python Minpower is designed to make solving ED , OPF ,and UC problems simple and intuitive. Traditional approaches to solving these problems are limited by: 1) low level languages; 2) expensive software; 3) being solver dependent. http://minpowertoolkit.com/ and http://minpowertoolkit.com/minpower.pdf
《 电力系统研究 》Electric Power Systems Research （Switzerland)刊载发电、输配电以及电力应用方面的原始论文。高价刊，用英文出版。(文种：英文) 《 IEEE电力系统汇刊 》IEEE TRANSACTIONS ON POWER SYSTEMS （ USA） 刊载电力系统包括发电和输配电系统的技术条件、规划、分析、可靠性、运行以及经济性方面的论文。(文种：英文) 《 英国电气工程师学会志:发电,输电与配电 》IEE PROCEEDINGS-GENERATION TRANSMISSION AND DISTRIBUTION(England) 《国际电力与能源系统杂志》International journal of electrical power and energy systems(England)主要发表电力与能源系统的理论和应用问题的论文、评论和会议报告，涉及发电和电网规划、电网理论、大小型系统动力、系统控制中心、联机控制等。读者对象为电气工程师。(文种：英文) 《电力部件与系统》ELECTRIC POWER COMPONENTS AND SYSTEMS (USA)刊载电力系统的理论与应用研究论文。内容包括电机的固态控制，新型电机，电磁场与能量转换器，动力系统规划与保护，可靠性与安全等。(文种：英文) 《电机与动力系统》ELECTRIC MACHINES AND POWER SYSTEMS (USA) 《英国电气工程师学会志:电力应用》IEE PROCEEDINGS-ELECTRIC POWER APPLICATIONS (England) 《IEEE电力系统计算机应用杂志》IEEE COMPUTER APPLICATIONS IN POWER (USA) 刊载计算机在电力系统设计、运行和控制中应用方面的研究论述。涉及瞬态网络分析、电路评价、稳态分析、电缆管理系统、相关的经济与事故分析等。 《IEEE电力输送汇刊》IEEE TRANSACTIONS ON POWER DELIVERY (USA) 针对安全、可靠而经济地输送和控制电能，刊载相关电力装置、设备、结构、材料与系统的研究、开发、设计、应用、制造、安装及操作方面的研究论文。(文种：英文) 《能量转换与管理》ENERGYCONVERSIONANDMANAGEMENT (England)刊载能源与能源系统及其调节与控制，包括核能与太阳能的利用，化学热能和电热能的发生与转换等方面的研究论文。高价刊。(文种：英文) 以上刊物同时被EI检索
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