On Jun 2, 2013, at 6:34 PM, Yi Liang wrote: > Dear all, > > I am wondering if the performance of current power flow analysis tool is good > enough in terms of speed. It really depends on your definition of "good enough" and the kind of analyses that you want to do. > 1, What is the size of a power system that is large in reality? 30,000 bus > -system? I think 10K+ bus transmission network can be categorized as large systems for power system problems. > What is the size of the United States power system? Western Interconnection bulk power grid model is about 15K buses and Eastern Interconnection about 40K+. U.S. grid I assume would be around 100k+ buses. > > 2, In the real industrial world, is there any requirements for the speed? > what is it? Yes and it depends on the kind of analyses that you'd like to run. I don't have a good idea about what is the industrial speed requirement. Maybe some of MATPOWER's industrial users can answer this but I assume the minimum requirement would be to have a power flow solution in under a minute? > > 3, If we use MATPOWER to solve the power flow analysis problems and the OPF > problems, how long will it take? I don't have that kind of test cases in > hand, so I cannot test them. MATPOWER's big test cases (~3k buses) take about 0.1 seconds for full AC power flow and about 5 seconds for optimal power flow on my machine. These numbers are based on the default data files provided with MATPOWER that include a "close to solution" initial guess. I've run cases around 20K buses and MATPOWER's full AC power flow takes about 1 second. In general, the time taken for these solvers depends on a number of factors such as initial guess, network sparsity pattern, loading conditions, constraints, hardware, cache, compilers. > Can anyone theoretically estimate the time complexity? As far as I know, it > depends on the iterations it takes for newton's method( for example, if we > use newton's method) For large systems, the most dominant operation is LU factorization and it consumes about 90%+ of the total solve time. So you could possibly do a crude theoretical estimate of the time for solving an AC power flow = time required for LU factorization X number of Newton iterations. For a given network topology the time for LU factorization would be fixed but unfortunately the # of Newton iterations vary depending on the loading conditions, initial guess, and possibly other factors. So determining the solve time theoretically is difficult.
Shri > > > Thank you! > > Best Regards, > Yi
