Review of power system simulation software tools

Power system simulation

Man at deskA power system simulation software models the behaviour of electrical networks, from low voltage distribution networks (typically 110 and 240 V) to very high voltage grids (up to 800 kV). They are mathematical models based on the electrical laws, offering a user interface specifically developed to represent networks equipment: substations, transformers, overhead lines, underground cables, generators, including renewable energy sources like wind farms and photovoltaic panels, circuit breakers, SVC, etc.

Large choice

DigSilentIt is difficult to know which are the most used in the world. Network simulation software developers do no publish the number of sold licences. Additionally, they propose different approaches and user interface functionalities, depending on their targeted clients. Utilities have different needs and objectives than consulting engineers or project developers, for instance. Different types of software are therefore available on the market. They all propose same kind of mathematical models (line and cable parameter calculation, load flow, neplanshort-circuit, stability, protection coordination, harmonics, etc.), but the user interface can be quite different.

etapAccording to my experience, the most used include Siemens PSS/E, Neplan, PowerFactory from DigSilent and ETAP. Other are EMTPEurostagCYMENAPPaladin DesignBase, CAPE, cymePowerWorldSimPow and Aspen, for instance. The list is not exhaustive and not ordered. Sorry for the ones that are not in the list. Feel free to add them by commenting this post.

In the past century

The first power system simulation software tools were developed in the 70’s. Some of them survive until today, going through punched cardsDOS, Windows 3.x, Windows 95 and subsequent versions, Fortran and procedural programming languages in general, floppy disksobject-oriented programming and now cloud computing and punch_cardprobabilistic methods. The most famous is certainly PSS/E, originally developed in the USA in 1976, now belonging to the German company Siemens, after being sold and transferred several times.

Thirty years ago, PSS/E reigned supreme amongst a few commercial available software tools. Many electrical engineers developed their own software tool too. Some of them evolved into commercial tools, increasing the number of PSS/E competitors. The majority remained in the office where they were created. The big majority of these tools, commercial or not, were developed in Fortran on DOS.

When Microsoft placed Windows 95 on the market in August 1995, some of the software developers made the effort to upgrade. The majority of them just added a windows user interface, without modifying the calculation modules. A minority took the opportunity to completely redesign their tools. New incomers also showed up with brand new tools. For instance, ETAP claims on its website that “in 1996 ETAP released the first, true 32-bit, power system analysis program on the market for Windows.” I am not sure it is true, but ETAP was surely amongst the Windows 95 pioneers in the power sector. But the real first-movers were the very few companies that developed windows user interfaces for such software on Windows 3.x, in the early 1990s.

mac_questionIt is interesting to note that all commercial power system simulation software tools are running on Microsoft Windows. None is running on MacOS. Is it a potential market for developers?

Tough competition

When the majority of power sector companies finally acquired Microsoft Windows in the late 1990s, early 2000s, software editors were forced to follow the move. PSS/E for instance released its first Windows version only in 2004, almost ten years after the release of Windows 95. And it was not a good one. Some data sets were still defined in per unit, for instance line characteristics (resistance, reactance, etc.). It is known that the power sector is conservative, but concerning IT, it is extremely conservative.

Now, commercial power system simulation software tools are modern and try to make the most of available IT technologies. In fact, natural selection catches up the others, the ones that didn’t evolve.

Better, but not good enough

psse_exportBut for the survivor, there is still room for improvement. The biggest problem for the user is data portability: it is a headache to export and import data between software. There is no standard exchange format. There were some attempt, but they all failed. Every company developed its own database and data organisation. In the best case, they propose import tools from competitors formats. But they are not working well, or they don’t work at all. I know that if power system simulation software editors will read this, they will claim it is not true. But as a user, and an experimented one, I feel comfortable writing it.

User interfaces also need makeover. Menus organisation is often absurd. I was also software developer, I know it is not an easy task, but they should put some effort on it. In a training session on one of these software tools, the trainer, an excellent senior employee working since many years for the editor, couldn’t find the menu activating a special functionality one of the trainee wanted to see. He had to ask several colleagues before finding one who knows where to find the right button on a windows one reaches after many clicks. Not to mention that it was not explained in the user documentation.

I will be nice. I will not show you screenshots showing how old fashion can be some interfaces.

Printing is apparently also a challenge for this type of software. If you succeed to get the font you want, the line thickness you want, the arrow size you want, on the paper size you want, all that at the same time, you are then sure that you are an expert user.

Last but not least, the price

pigI don’t know what is your opinion, but several ten thousands dollars for this kind of software is too much. I know the market is not so big, and they the number of sold licences is limited. But the price is a barrier to acquire more licences. I have seen many companies with one licence shared by several employees, only because it is too expensive to acquire one licence per employee. Declining prices are generally proposed when buying several licences, but the proposed discount is no a sufficient incentive. Opinion from software editors is here welcome to explain us their price strategy.

A quiet revolution 

To finish on a positive remark, let’s look at the progress we made. Forty years ago, it took about a minute for simulating a  medium-sized network, plus the time necessary to prepare the data in the right format in ASCII files. Now, it is possible to calculate hundreds of load flow simulations in a few seconds. And databases allow us to organise the data for us.

Gauthier Dupont
Dupont Energy Consulting GmbH

About Dupont
Dupont Energy Consulting GmbH Owner & Director http://www.dupontconsulting.de

8 Responses to Review of power system simulation software tools

  1. Santoshi rawat says:

    Dear Sir,

    As you have mentioned above that there are many software used earlier for power system simulation. Could you please suggest which one is the best and why.
    Actually currently I am working on Eurostag and find that software quite good. But still I am facing some problem in it. So please suggest me which one is better than this software and in what prospects.
    Please do let me know how ETAP is useful than Eurostag.

    Regards
    Santoshi

    • Dupont says:

      The choice depend of the functionalities you need. For detailed stability study, I would recommend Eurostag. But if you need to simulate many load flows for long-term planning studies, it is too heavy (squashing a fly with a sledgehammer). For planning study, Neplan and Digsilent are easier to use and more flexible, even if you need to run some stability simulations. When data are missing or have to be estimated (the future is not known), and when many scenarios have to be simulated for long-term planning, NAP is a very good alternative. It is the best OPF (and probably the only real one) on the market, but certainly not the best tool for detailed stability studies. http://www.systemseurope.be/products/nap.en.php. Short-circuit is very easy with NEPLAN, as well as voltage stability simulations.
      i hope this would help you to decide. You can also download demo version or ask for one. Software editors would certainly give you a demo to test. Invest some time before taking decision. But know what is the most important for you: OPF, easy to use, scenarios management, design up to the last screw, etc.

  2. Yoges says:

    Hi,
    Can you provide any document or study for an insight into history and evolution of power system software tools?

    • Dupont says:

      The article is based on my professional experience. I unfortunately never developed any comprehensive study on power system software tools. I remember I read some books on the topic, but they were relatively old and they explained the old time of Fortran software. They do not include modern tools.

      It is maybe a good topic for a book still be be written.

  3. N Ramesh says:

    Hi!
    Good article with nostalgic records of punched cards, floppy disks and FORTRAN 77. CAPS (Computer Aided Power System Analysis Software) from India in one such legacy software. Since it was not marketed outside the country, not many people are aware. But it was used by many power utilities within India. It was first developed on FORTRAN 77. All calculations were done on ForTran (Formula Translation) language and front-end GUI for SLD creation and editing using Pascal language. During those times, if I am not wrong, even PSS/E did not have GUI. Many other commercial products used AutoCAD for drawings and then superimpose the results using DXF exchange program of AutoCAD. Even CAPS used AutoCAD as some of their customers insisted that their drawings should be in AutoCAD DWG format. During those days Pascal was good at handling graphics on DOS. GUI in CAPS was intuitive. CAPS worked on DOS 3.1 thru DOS 6.22. From PC/XT to PC/AT to Intel 486 SX. There used to be two processors on the motherboard – one main processor and the other floating-point unit or more commonly called math coprocessor. Math-coprocessor was optional and was installed only when the PC is used for high-end applications involving a lot of number crunching tasks such as graphics, power system analysis and other engineering purposes. Intel 80307 was math coprocessor of Intel 80306 and Intel 80487 was math coprocessor for Intel 80486

    CAPS was renamed as MiPower while it was ported to first 16 bit Windows Platform and was available on Windows NT 3.0 / Windows 3.11. Later with the release of Windows 95, it was migrated to 32 bit. There were many issues with the new Windows until many patches and upgrades were released. Windows 98 SE (Second Edition) was one of the most stable Windows OS in late 90s. Today MiPower is migrated to the latest development platform and works on multicore 64 bit workstations and high end blade servers. MiPower is widely used by many utilities around the world and a lot of academic / research scholars find it very useful for the kind of features and facilities it has.

    N Ramesh

  4. sam says:

    is there any of these software are good for VFD,Medium voltage drives ,for motor starting or Harmonic analysis.

  5. samrat says:

    We are evaluating tools to conduct relay database management, relay setting management and relay engineering. Do you have views on which ones (CAPE, ASPEN, IPS, Digsilent,…) are most optimal? i understand IPS and CAPE have collaborated to create a bundle product. Wondering if that is the best option in the market these days.

  6. Chintan Shah says:

    Thank you for the detailed guidance. I do agree, its difficult to indicate best software, but if can be analysed for two software DIgsilent and EMPT.
    Can you please guide on advantages and disadvantages of Digsilent vs EMTP?

    Thank you in advance.
    Chintan

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