Hoping to remedy an electrical problem common in microgrids, scientists from the Northeastern University, China, have detailed a new approach to diagnosing the issue in IEEE/CAA Journal of Automatica Sinica (JAS), a joint publication of the Institute of Electrical and Electronic Engineers (IEEE) and the Chinese Association of Automation.

Like an island, microgrids are isolated pods of power generation linking to the main power grid. If there is an interruption of power from the main grid, the microgrid can disconnect and continue to supply power locally.

"In response to societal requirements, [the] microgrid system has received considerable attention," wrote Prof. Zhanshan Wang and Prof. Huaguang Zhang. "The reliability of the inverter is considered an important factor to guarantee the high quality, continuousness, and safe operation of the microgrid."

The inverter can convert the direct current from the main grid into an alternating current—something household electronics can use.

For instance, the power flows through a circuit to operate a computer or coffeemaker until the device is no longer needed, which causes a switch to interrupt the circuit and redirect the current to power another device. However, sometimes the switch sticks, causing the current to continue to flow.

"[An open-switch fault] often affects the normal operation of the entire drive system and causes many serious influences," said Wang. "For example, [it can cause]...overcurrent stress to other power switches or electronic components...low efficiency; [and] high repair costs."

The issue can be easily corrected by flipping the switch back on—if you know there's a fault and where it is located. A switch fault (which can cause an electrical fire) may not be obvious until it is too late. Because there are so many switches throughout the microgrid system, it's almost impossible to find which one is at fault.

In an effort to resolve this problem, researchers developed an algorithm to identify multiple signals at multiple levels in the circuit, helping to determine if a switch fault exists. The switch fault’s location can be determined through an artificial neural network—a network of computers that learns to process information based on the information itself.

Both the algorithm and the neural network can work together to simultaneously detect and identify the exact open-switch fault, according to the researchers, improving the cost, reliability and efficiency of the microgrid.