In recent years the demand for photovoltaic and wind power generation as an alternative energy source is increasing. However, the power generated is often affected by weather conditions and can cause stability issues for the grid. In order to optimize the use of alternative energy and balance the grid to achieve peak load shifting, some countries are starting to promote hybrid types of photovoltaic and wind power storage systems with the combination of intelligent houses and electric vehicles to structure a micro-grid. This creates a need for more stringent simulation tests for power stability, safety and abnormal conditions for grid tied installations. Figure 1: Micro-Grid
The Chroma 61800 Series Regenerative Grid Simulators can provide the conditions necessary for testing micro-grids, such as harmonic voltage distortion and frequencies to simulate the power gird features, by supplying a maximum of 690VLL (400VLN) voltage and up to 300kVA power output. Most importantly, the regenerative feature of the 61800 grid simulator provides an effective energy saving method, since energy generated by the UUT is fed back to the grid instead of dissipated as heat during operation. This four-quadrant operation capability meets the micro-grid testing requirements perfectly. As the input side of 61800 Series products includes isolation for the AC grid, there is no need to install any additional isolation devices at the UUT side of a simulated micro-grid.
Figure 1: Micro-Grid
Grid-connected distributed generation equipment standard tests
The 61800 series Regenerative Grid Simulator is capable of meeting the following regulations designated for Grid Tied Discrete Generator testing: IEEE 1547 / IEC 61000-3-15 / IEC 62116. Below are some of the main test items:
- Voltage Abnormality Test
- Frequency Abnormality Test
- Anti-islanding Test
- Low Voltage Ride Through Test
- Immunity Test (voltage change) (IEC 61000-4-11/-4-34)
- Limit Test (current harmonic & flicker) (IEC 61000-3-2/-3-3)
Low Voltage Ride Through (LVRT) Test
The Low Voltage Ride Through (LVRT) function of grid tied PV inverters clearly defines when an abnormality occurs on the grid (such as a voltage drop), the PV inverter must remain operable and sustain the main AC grid for a specific time period. For instance: the BDEW standard requires the PV inverter to remain operable and delivering reactive power for at least 150ms when the grid voltage has dropped to 15% of the nominal value. The 61800 Regenerative Grid Simulator is fully capable of meeting the LVRT test requirements, as the user can program the required transient test conditions by implementing the LIST mode function with a minimum time resolution setting of 0.1ms. Moreover, the user can also study and evaluate the impact on PV inverter performance due to grid line voltage distortion by implementing the harmonic synthesis function of the 61800 series product. The frequency resolution of the 61800 is 0.01Hz which meets the BDEW requirement.
The Chroma 61800 Series Regenerative Grid Simulators have been adopted worldwide by well-known manufacturers and third party laboratories in testing and validating micro-grid related research as well as PV inverters’ production. To learn more about the 61800, please visit our company website:http://eu.chromaate.com/product/regenerative_grid_simulator_61800.htm