Why choose NI for Microgrid and Distributed Generation Control?

Überblick

Microgrids help control the dynamic nature of distributed generation and add a level of resiliency to the grid. They also bring a different set of challenges to grid operators since the grid was not designed with distributed generation in mind and microgrids are often unique combinations of all types of generation, storage, load, and function. NI controllers and platform software have several advantages that help utilities, power systems engineers, and grid researchers better control field deployed microgrids. This paper covers four specific benefits of NI technology for microgrid and distributed generation control and monitoring systems.

Table of Contents

  1. Open Platform to Provide a Custom Controller
  2. Over 100 Modules For Sensor and Signal Compatibility
  3. Protocol Flexibility to More Easily Integrate Into Existing Systems
  4. Flexible Control Capability to Handle a Wide Variety of Microgrid Functions
  5. Conclusion
  6. Additional Resources

Open Platform to Provide a Custom Controller

Microgrids often have unique features.  Even within a single microgrid, the controllers and measurement devices can have different needs.  Microgrid measurement and control devices designed on NI technology are built on a platform with hundreds to thousands of possible hardware configurations and infinite possibilities once you consider software programmability.  Some of the main platform features include:

  • Fully programmable controllers to run virtually any algorithm, measurement processing, or control logic (Program the controller with LabVIEW or C/C++ and the FPGA with the LabVIEW FPGA module)
  • Open RTOS, NI Linux-RT, with source code available to enhance the OS using Linux expertise or by leveraging packages from the existing Linux ecosystem
  • Hardware Controllers available with a variety of processor, RAM, and solid-state storage options in addition to over 100 sensor and signal modules (more info below)

Figure 1. CompactRIO is powered by LabVIEW and combines an open, embedded, controller architecture with industrial sensor and signal I/O modules.

 

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Over 100 Modules For Sensor and Signal Compatibility

The CompactRIO hardware family has over 100+ NI designed and manufactured sensor and signal modules for input and output.  Common modules for the T&D industry include:

  • CT input module compatible with 1A or 5A CT secondaries
  • PT input module compatible with 120V or 240V voltage secondaries
  • ±10V and  ±60V input modules for low voltage sensors
  • 250V variable threshold digital input module for binary input
  • 24V industrial digital input module
  • 24V industrial digital output module (often used to drive 110/220VDC relays for binary output)
  • GPS for time synchronization

Other modules include a wide variety of sensor modules for temperature, pressure, flow, linear displacement, rotation measurement, etc.  These sensor modules can be used to add functions such as:

  • Environmental monitoring for forecasting and efficiency calculations
  • Transformer/asset health monitoring for predictive maintenance and failure mitigation

Figure 2. Over 100 modules for CompactRIO are available for sensor measurement and control I/O.

 

Additionally, a module development kit is available for 3rd parties to develop custom hardware C Series modules for CompactRIO.  There are over 100 modules available on the open market that are designed and manufactured by 3rd party companies.  When combined with modules from NI, there are over 200 C Series modules available for CompactRIO.

 

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Protocol Flexibility to More Easily Integrate Into Existing Systems

The CompactRIO controllers have various hardware communication ports available, such as ENET, RS-232, RS-485, but the protocol used is software defined by the designer.  DNP3, IEC 61850, EN60870, Modbus, TCP/IP are all protocols that have functions available for the LabVIEW development environment.  Not only are they programmable and upgradable over time, but a single system can speak multiple protocols helping to bridge SCADA, EMS, and local microgrid control systems.  Custom protocols, owned by other vendors, can run on NI hardware provided the owning vendor provides an API for LabVIEW or plug-in software element for Linux.

Connecting to alternate physical communication layers, such as WIMAX, GSM, LTE, etc. is often accomplished through connection of an external modem/router to the NI controller via ENET or Serial.  Alternately, companies like SEA Gmbh. manufacture wireless and cellular C Series modules that are compatible with CompactRIO.

 

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Flexible Control Capability to Handle a Wide Variety of Microgrid Functions

Processors available in CompactRIO chassis range from a dual core ARM9 to a quad-core INTEL based processor clocked at 1.91 GHz/core.  Between the processor and I/O modules of every CompactRIO is a programmable FPGA.  The FPGA brings several features to utility applications due in large part to it's combined processing speed and parallel nature.  These features include:

  • Use as an in-line coprocessor for digital filtering, resampling, and some power analysis
  • Time stamp synchronization between GPS clock and data samples
  • Assist with high speed I/O calculations and control for protection relay functions

The processing capability and open programmability mean microgrid controllers designed on CompactRIO are suitable for a variety of measurement and control functions such as:

  • Generation smoothing
  • Intelligent demand response and peak shaving
  • PQ and telemetry data
  • Intelligent energy storage controllers
  • Microgrid command control
  • Custom relays designed for specific renewable problems (sub-synchronous oscillations (SSO), harmonic detection, low-voltage ride through, etc.)

 

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Conclusion

An off the shelf solution covering all microgrid challenges does not exist.  Open, programmable, flexible solutions built on NI technology are an ideal fit for custom issues that would otherwise require a new design, or a cobbled together solution of existing equipment and industrial computers running patch software to connect all of the systems.

 

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Additional Resources

 

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