Clean energy is vital to an evolving world and its increasing use of electronic devices, and a distributed power grid provides the means to provide that power. In a distributed power grid, the energy comes from many different sources and technologies, including solar power inverters, hydroelectric power, and wind power generators. Distributed energy resources (DERs) that are sometimes part of a power grid are switched on and off as needed according to user requirements. Efficient management of a distributed power grid requires such capabilities as remote control of the microgrids or different portions of the grid, so that they can be switched in and out as power is needed and, especially, regular measurement and maintenance of the performance of the different parts of a distributed grid.
With the growing roles of electric vehicles (EVs) as part of distributed power grids, with their batteries being charged but also used as energy storage locations for the grid, testing of the grid must adapt and evolve to changing needs. Measurements are performed according to established energy standards and with test equipment designed for testing a distributed power grid and its components. By knowing the measurements needed for testing and simulating the performance of a distributed power grid, the task of specifying the right test equipment for those measurements is much simpler.
Test equipment that simulates a distributed power grid should be capable of replicating the full range of conditions that may be found on an actual power grid. Such testers/simulators are vital not only for testing and maintaining the component parts of a distributed power grid, such as power inverters and converters, but for testing electronic products and appliances that will rely on the grid for their power. Quite simply, a distributed power grid simulator should appear as a power grid to the equipment that it is testing.
In general, a distributed power grid simulator or test system should be sized according to expected measurement requirements, with suitable excess capacity, such as 20%, to handle any future requirements. Any power grid measurement solution should have the voltage and current ranges suitable for performing measurements on the various component parts of a distributed power grid, such as the many types of inverters, and provide the measurement resolution and accuracy for meaningful measurements. It should be capable of generating and analyzing not only clean power but distorted power waveforms (such as with harmonic content) as may be required by conformance and validation testing, and should have the versatility of multiple channels and the capability of supplying single-, two-, and three-phase power outputs for testing. Additional useful capabilities, especially for production testing, include programmability and digital interfaces for control with an external computer and the appropriate software.
As examples of differences in measurement capacity, the 61830 and 61860 regenerative grid simulators from Chroma are both members of the company’s 61800 series of regenerative grid simulators, but with different limits in power generation and analysis capability, allowing a test equipment specifier to choose as much measurement power as needed. The 61830 is rated for 30 kVA maximum power while the 61860 can generate and analyze power to 60 kVA. Other than their maximum ratings, the two test systems feature flexible measurement capabilities, with four-quadrant, fully regenerative operation, output voltages at DC and AC voltages from 30 to 100 Hz, with voltage ranges of 0 to 300 V. In addition, these and other members of the firm’s 61800 series of regenerative grid simulators are equipped with six test channels and one-, two-, and three-phase power generation capabilities. They include extensive programmable functions, including programmable voltage and current limits and programmable slew-rate settings. The test systems also incorporate GPIB, RS-232, USB, and Ethernet interfaces for ease of connection to an external computer, for control and data collection.
Similar to the Chroma 61800 series, the California Instruments MX series is a very popular and proven AC source, regularly used for grid simulation testing. The MX30, MX45, and MX90 are the mainstay models of the series. With a slew of available features, and optional capabilities such as “Regenerative Source” functionality, there are few grid simulation tests that the MX series units cannot handle. In spite of extremely high demand for the MX series, Axiom strives to keep several units available for rent at all times, for short- and long-term testing requirements.
Another example of how specifiers of distributed power grid simulators can select a test solution based on measurement requirements is the 9410 series of simulators from NH Research, with a total of eight models ranging from 8 kVA to 192 kVA and respective power levels from 4 kW to 96 kW. Depending upon model, these simulators are rated for AC outputs from 0 to 310 V RMS with options as high as 400 V RMS. These are modular systems that can be reconfigured (adding 12-kW modules) as needed for additional power and measurement capabilities. As with the Chroma simulators, the 9410 series simulators are capable of different output voltages at DC and AC voltages from 30 to 100 Hz, and operation in one-, two-, and three-phase modes. In addition to flexible programmability, the 9410 series simulators simplify control and testing by means of a 9-in. touch-panel screen.
Is the NHR 9410 series of simulators a product or type of product that you foresee needing for a short-term rental basis? Let us know what you think. E-mail us through our sales department, sales at axiomtest.com, or send us a message through our contact page found here: http://www.axiomtest.com/contact-us.php.
Distributed power grid simulation can be performed with as much or as little measurement capability as needed, by specifying a simulator per the test requirements, with an eye towards future needs. The emergence of EVs and hybrid electric vehicles (HEVs) will certainly impact future grid simulation requirements as these vehicles add significantly to the total energy demands of full-sized grids and micro grids.