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Enhancing Substation Reliability, Availability, and Maintainability

IEC 61850 Makes Substations Smarter

The primary purpose of IEC 61850 is twofold. First, IEC 61850 establishes future-proof interoperability guidelines for all automation and remote management systems, so that any later advances in hardware or communications technology will remain backwards compatible and consistent with a single set of protocols. In this regard the focus is primarily upon standardizing the communications architecture of intelligent electronic devices (IED). Secondly, IEC 61850 sets a minimum set of technology features that push new controls and automation deep into the substation’s process layer, thus allowing for real-time monitoring and management from a centralized remote control station.

Power companies gauge achievement according to service quality, which is defined in terms of reliability, efficiency, security, and productivity. While IEC 61850 standardizations improve substation operations in each of these respects, it is does not serve (and is not intended) as a comprehensive solution to every automation problem. IEC 61850 leaves open the question of what, and defines only the how: there remain a great many automation challenges which have been left unaddressed, and overcoming them is the primary means by which IEC 61850 compliant device manufacturers may add value to their products.

IEC 61850-3 Class C3 and IEEE 1613 Certifications

In other articles, we have explored the basic requirements for an industrial-grade IEC 61850-3 / IEEE 1613 compliant substation device. There are three our four key points which every substation device should today meet:

• Strong EMI protection in the form of full Level 4 EMC over communication and power interfaces

• -40 to 75°C ambient temperature tolerance, preferably in a fanless enclosure

• High tolerance of strong vibration and shock

Each of Moxa’s IEC 61850 compliant devices meet all of these basic requirements.

Moxa Innovations

With Moxa’s new generation of substation computing and networking equipment, we have brought our know-how to bear on issues that lie both within and without the current scope of IEC 61850, addressing both specialized automation needs and general industry trends. In particular, our new generation of devices provide:

• Zero Packet Loss at Wire Speed

• Digital Diagnostic Monitoring (DDM) for Fiber Links

• Side-by-Side SNMP and MMS: Advanced, Next-Generation Monitoring Integration

• Remote or Automatic Smart System Software / OS Recovery

Zero Packet Loss at Wire Speed

Packet loss in substation communications introduces unpredictable risk that, in worst-case scenarios, can threaten a substation system with catastrophic, permanent failure. After addressing IEC 61850’s EMC requirements, to fully satisfy current IEEE 1613 Class 2 requirements all devices must further communicate critical, low-level GOOSE/SMV multicasts at the highest priority. GOOSE/SMV must always be transmitted at the highest priority, without fail, throughout the entire network, regardless of transient network conditions; achieving this means switches must support strong QoS traffic shaping.

Traffic shaping switches scan the Ethertype field of every transmitted packet and then automatically bump GOOSE/SMV messages to the top of the routing queue, so that critical messages are delivered immediately, as they are sent out, regardless of however much other data is being communicated along the network.

Digital Diagnostic Monitoring (DDM) for Optical Fiber Links

One of the key areas left undefined by IEC 61850 where improvements may be madeis in hardware designs for optical fiber lines. In fiber-optic communications, hardware performance is measured by the duration of successful operating time; however, high temperatures reduce the lifetime of optical fiber cabling significantly. Preventing fiber malfunctions with a pre-fault predictive maintenance mechanism is highly desirable, but at the moment most substations only support SFP-type optical fiber monitoring, leaving ST/SC connectors entirely outside the scope of the PdM system. Digital diagnostic monitoring (DDM) is what is needed: using DDM, substation switches can monitor ST/SC as well as SFP connectors, and notify power SCADA systems via SNMP trap or MMS when abnormalities are detected. DDM reports and alarms may be communicated over a web, CLI, or serial console; via MMS reporting or SNMP traps; by a digital relay; or in the system log. Several methods may be used, to provide redundancy. This arrangement further allows system operators real time monitoring of things like transmission and reception power, temperature, and voltage/current along optical fiber connections.

An overview of an IEC 61850-compliant substation highlighting
optical fiber links with DDM (in yellow) and dual SNMP/MMS monitoring

Side-by-Side SNMP and MMS Support:
Integrating Network Monitoring Solutions for Power Substation SCADA

Currently, substations are forced into the uncomfortable marriage of two protocols: SNMP is used for IT devices (because MMS doesn’t work with IT devices), while MMS is used for everything else (because SNMP can’t carry IED process information). This is inconvenient for system administrators and expensive for operators. Moxa, however, is already working to provide a solution: we have integrated MMS into our SNMP-capable Ethernet switches and substation computers. With MMS-capable IT hardware, substation SIs and automation engineers will be able to render a full accounting of the entire network right alongside process layer reports, all under a single SCADA view. Station operators will gain more effective and reliable automation, noticeable improvements in management efficiency, and finally a reduction in deployment costs. Integrating MMS and SNMP on IT devices will allow administrators to:

• Monitor and control IEDs, switches, embedded computers, device servers, and process data from a single power SCADA interface

• Eliminate redundant SNMP systems for IT hardware while decreasing network congestion

• Configure devices for event triggers, polling reports, or both

• Precisely locate devices relative to other devices within the network hierarchy in a single software view

• Directly configure and control IT hardware

• Perform batch configurations using CID (Configured IED Description) files

OS Smart Recovery:
Remotely or Automatically Trigger Computer Software System Recovery

Last but not least, Moxa is also delivering strong software solutions that will greatly simplify the task of maintaining automated IEC 61850 substations. Up to now, there has been very little a remote system administrator could see or do when a device failed; when options are available, they generally are restricted to hardware re-boots or hard device resets. This leaves the possibility of failure from corrupted system software, whether it is in the OS or in local scripts. Software corruption can be catastrophic for remote industrial installations and sites with mass computer deployments. With some estimates of computer failure attributed to software corruption as high as 30%, automated BIOS-level software recovery systems are an extremely valuable design addition to power substations, whether remote or local.

Without an effective recovery system, if a hard reset doesn’t fix a software problem then diagnosis and maintenance will require the physical presence of an engineer. When the sites in question are extremely remote—as with windfarms, pipelines, or desert locations—that translates into a lot of expense and downtime. Moxa’s response to this situation is its Smart Recovery software utility, which comes on all of our latest generation of substation comptuers. Smart Recovery allows engineers to remotely monitor a computer’s health and, if they feel it’s necessary, to trigger a full rewrite of the entire software platform—both the OS and any local scripts or other customized configurations. Additionally, however, Smart Recovery may be automated as well, to respond to a range of conditions in an attenuated manner, triggered by SNMP traps, spontaneous crashes, or other undesirable conditions.

With Smart Recovery, a read-only disk image is created when the computer is first deployed, and is used as a master disk image whenever a system rewrite is required. The method is not new, but now it comes in a pre-installed, ready-to-run software application on every Moxa substation computer.

Moxa’s latest array of software and hardware innovations are giving substation administrators and operators tangible value by anticipating IEC 61850 coming amendments while building on its existing IEC 61850 requirements. Moxa’s latest generation of substation computers and switches is improving the overall substation environment in practical, reliable ways that give immediate returns as soon as they’re deployed. Come read more about Moxa’s substation advances on our website, or study our latest whitepapers: Making Smart Substations Even Smarter, and Using MMS and SNMP to Integrate IT Management.

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