This week I was asked the question in the title during an introduction of IEC 61850 to some 15 utility experts. My response was not just yes or no. Initiated by that question I thought it would be of interest to discuss this issue on the blog.
We have to understand that the expected complexity in power system information exchange has at least the following three crucial aspects:
- Complexity of the network infrastructure (independent of protocols defined and used by standards like IEC 60870-5-104, DNP3, IEC 61850, IEC 61400-25, …). The infrastructure used and discussed these days seems to explode! Compared to dial-up-links and and fixed land lines used usually for remote access of something, the application of Switched Ethernet, Ethertype, VPN, VLAN, TCP/IP, UDP/IP, GSM, UMTS, LTE, … requires a good understanding of your needs and the various solutions that could be used.
- Complexity of standards (like IEC 60870-5-104, DNP3, IEC 61850, IEC 61400-25, …) that use the above infrastructure.
- Complexity of communication software and application interfaces between applications and communication software, and complexity of engineering and configuration tools.
In many cases I have experienced that users do have little understanding what they really need! And may even have lesser knowledge about the various solutions, how to use them for their systems, and to understand how they impact the dynamics of the whole system!
I have talked to many people that have complained about the complexity of protocols … but usually we figured out that the complexity was caused by a bit of everything … and mainly by the fact that people tend to NOT TRUST the chain of solutions from, e.g., a control system application to an API of a front-end, front-end application, protocol API, protocol IEC 60870-5-104, TCP/IP, VPN, GPRS, RTU, interface between RTU and remote application, and remote application.
Here is an example I have experienced recently (with the topology based on GPRS as listed above):
- The control system does not trust that the information exchange with the RTU is reliable and available. Therefore the control system sends Pings every 2 seconds.
- The front-end application does not trust that the RTU is reliable and available. Therefore the front-end applications issues a 104 control command (toggle bit) every 10 seconds … just to see if the 104 protocol is still alive.
- The front-end application does not trust (even it figures out that the RTU is available) that the remote application is really receiving a parameter setting for a function in the remote application. Therefore the remote application copies a received setting value to another 104 information object and sends a spontaneous message with the just received setting value.
- The protocol IEC 60870-5-104 exchanges flow control messages to acknowledge the received messages (in both directions).
- TCP uses flow control messages and keep alive messages …
So, what do you think about such a bunch of deep mistrusts? Do you think that such a system would work properly and reliable?
I guess that there are many huge GAPS: in the understanding of the NEEDs, the various links in the chain like the dynamics of a system using, e.g., GPRS, … the APIs, the applications …
I recommended to the audience that there is a crucial need for: MORE EDUCATION !!
A screw driver is not sufficient for future power delivery systems. And: Ignoring IEC 61850 is not sufficient to get the job done! IEC 61850 solutions can be very easy for simple needs.
You can experience it – if you want! Let me know!
1 comment:
Dear Mr. Schwarz you are totally right, here in Brazil we have the same problem with our power utility specialists.
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