Renewable energy-based generators are constantly being deployed to future grids. It is expected that their share in overall generation will increase in the future. These novel devices have unknown characteristics and cause novel issues in power system operation. Traditional distribution networks have been operated as passive networks. These devices, such as smart inverters, change this paradigm completely. Due to these considerations, grid operators insist on enforcing strict grid-integration requirements. These rules are developed to ensure the impact of the connected devices is minimized and their behavior can be accounted for, at least to some extent. Testing different devices for different grid codes is a daunting task. Since such tests are undertaken in lab environment with manual control and data collection, they are prone to errors, time-consuming and inefficient. A solution is required to standardize and automate such tests. This will provide consistent testing ability and minimize testing times and errors due to human-intervention. This article presents the design and implementation of an integrated testing platform. Steps of lab equipment integration and associated challenges are presented along with their solutions. Several smart inverter behavior tests are executed, and results are presented. The test durations are compared with traditional test durations and the benefits are reported. It is discovered that use of such platform can increase the system testing efficiency by 85 % while minimizing human-errors, inconsistencies and man-hours required to run the tests.

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Required functions of a microgrid become divers because there are many possible configurations that depend on the location. In order to effectively implement the microgrid system, which consists of a microgrid controller and components with distributed energy resources (DERs), thorough tests should be run to validate controller operation for possible operating conditions. Power-hardware-in-the-loop (PHIL) simulation is a validation method that allows different configurations and yields reliable results. However, PHIL configuration for testing the microgrid controller that can evaluate the communication between a microgrid controller and components as well as the power interaction among microgrid components has not been discussed. Additionally, the difference of the power rating of microgrid components between the deployment site and the test lab needs to be adjusted. In this paper, we configured the PHIL environment, which integrates various equipment in the laboratory with a digital real-time simulation (DRTS), to address these two issues of microgrid controller testing. The test in the configured PHIL environment validated two main functions of the microgrid controller, which supports the diesel generator set operations by controlling the DER, regarding single function and simultaneously activated multiple functions.

Deep penetration of distributed generators have created several stability and operation issues for power systems. In order to address these, inverters with advanced capabilities such as frequency and reactive power support the grid. Known also as Smart Inverters (SIs), these devices are highly dynamic and contribute to the power flow in the system. Notwithstanding their benefits, such dynamic devices are new to distribution networks. Power system operators are very reluctant toward such changes as they may cause unknown issues. In order to alleviate these concerns and facilitate SIs integration to the grid, behavior studies are required. To that end, this paper presents a power hardware-in-the-loop test set up and tests that are performed to study fault behavior of SIs connected to distribution networks. The details of the software model, SI integration with the real-time simulator, test results, and their analyses are presented. This experience shows that it is not trivial to connect such novel devices with simulation environments. Adjustments are required on both software and hardware fronts on a case-by-case basis. The encountered integration issues and their solutions are presented herein. The fault behavior of the SI with respect to the fault location is documented. It is observed that for faults that are close to SIs, momentary cessation of generation is observed. This needs to be tackled by device manufacturers as this phenomenon is very detrimental to health of a power system under fault conditions. Extensive PHIL test results show that several factors affect the fault behavior of an SI: fault location and its duration, SI mode of operation as well as extra devices housed in the casing. These results and their in-depth analyses are presented for a thorough understanding of SI behavior under fault conditions.

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