computer science

OpenPDC

OpenPDC is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand OpenPDC rather than just read about it. In short: The openPDC is a complete set of applications for processing streaming time-series data in real-time. The name stands for "open source phasor data concentrator" and was originally designed for the concentration and management of real-time streaming synchrophasors.

Key takeaways

OpenPDC belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect OpenPDC to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of OpenPDC from memory before moving on to harder problems.

Reference excerpt

The openPDC is a complete set of applications for processing streaming time-series data in real-time. The name stands for "open source phasor data concentrator" and was originally designed for the concentration and management of real-time streaming synchrophasors. Due to the system's modular design, the openPDC can be classified as a generic event stream processor.

History The openPDC is based on the Super PDC which was developed by the Tennessee Valley Authority starting in 2004. The openPDC officially launched on October 7, 2009. The first stable release of the openPDC was made available on January 28, 2010. Then on February 23, 2010, AREVA T&D announced that they would be providing commercial support for the openPDC. Finally, on April 1, 2010, the Grid Protection Alliance inherited development of the openPDC and entered into a contract with the North American Electric Reliability Corporation in an effort to further enable its use as a distributed system.

Operation The phasor data concentrator runs as a Windows service. The service is responsible for managing the life cycle of adapters that create and process the streaming phasor measurements. Adapters are split into three layers:

The input adapter layer is typically responsible for receiving data from an outside source such as a phasor measurement unit. That data is used to create measurements which are sent to other adapters to be processed or archived. The action adapter layer is typically responsible for concentration and processing of the input measurements. Adapters in this layer can also introduce new measurements to the system, just like adapters in the input adapter layer. The output adapter layer is typically responsible for archival of measurements received from the input adapter layer and the action adapter layer. These adapters can be configured using any one of three supported database systems: Microsoft SQL Server, MySQL, and Microsoft Access.

Features The openPDC implements a number of standard phasor protocols which can be used to receive data from devices. The supported protocols are IEEE C37.118 (v1.0 and Draft 6), IEEE 1344, BPA PDCstream, FNET, SEL Fast Message, and Macrodyne. There is also a built-in concentration engine which sorts the real-time data into frames based on the timestamp associated with each measurement. The sorted measurements can then be streamed to other applications using either IEEE C37.118 or BPA PDCstream. The system is capable of concentrating over one billion measurements per day coming from over 100 phasor measurement units across the Eastern Interconnection. The project includes a historian for data archival. The files produced by the historian can later be analyzed using Hadoop. The historian is also designed to be used in distributed systems, having a single node dedicated to archival and several others sending concentrated measurements to the central archive. This design even allows for its use in any distributed system enabling one PDC to filter measurements to another that is running a resource intensive adapter. The local historian provides web services which can be used to monitor the data being archived in real-time. The data quality monitoring adapters provide information about measurements entering the concentrator that have flat-lined, gone out of a specified range, or entered the concentrator with a bad timestamp.

Applications Applications included in the openPDC project:

The openPDC Console is an application that can be used to send and receive messages between the openPDC service and a client machine. The openPDC Manager is a utility intended to allow remote access and simplify adapter configurations in the database. The PMU Connection Tester can be used to view a live stream of data in one of the supported protocols in order to test that the stream is being received. This tool has been used around the globe and can be installed separately from the rest of the suite. The NASPI PMU Registry allows users to register phasor-related devices to one central location to allow access to information about existing devices and their configurations. Configuration Crypter is a utility for encrypting options in the configuration files. Configuration Editor provides a simple GUI-based application used to modify the XML configuration files.

Worked examples

Example 1 — a first encounter with OpenPDC

Start with the simplest possible case. Write down what OpenPDC claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to OpenPDC before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about OpenPDC ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of OpenPDC

In research: OpenPDC appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses OpenPDC in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: OpenPDC is common in secondary-school and first-year university syllabi. It links to neighbouring topics Electrical meters, Free software programmed in C Sharp, Industrial software, so understanding it makes those chapters shorter.
In everyday life: Look for OpenPDC outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study OpenPDC in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what OpenPDC means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain OpenPDC out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is OpenPDC in simple terms?

Why does OpenPDC matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study OpenPDC?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on OpenPDC.