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Switch-model power electronic inverters are heavily deployed as the main technology in enabling flow of variable DC power into the AC grid. Various distributed energy system (DES) architectures have been designed depending on many attributes including size and application of the installed system. The reliability of the power electronic interfaces (PEI), i.e. inverters is critical in all these architectures. Recent studies demonstrate enhanced operation of a PEI can be reached by optimum adjustment of its controller parameters. While conventional tuning methods are mostly based on trial and error, their optimum performance can be achieved for primarily first-order systems. For systems with increasing number of PEIs or more complexity, application of these tuning methods becomes challenging and expensive. Thus, considering the operational performance of DES, a controller self-tuning methodology has been presented for PEIs with particle swarm optimisation capability. The optimal parameters for both kW-scale and multi-megawatt PV systems' inverters are determined via a timedomain performance objective function. Typical PV system performances are presented for step changes and dynamic weather conditions. Effectiveness of the controller self-tuning methodology has been demonstrated via the reduction of transient energy, when the system is subjected to dynamic changes and disturbances.

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Preservation of wind turbines (WTs) grid-connectivity during grid faults and grid-code (GC) compliant reactive power injection at PCC during voltage drops is an imperative task to perform in modern WTs. This is known as the low-voltage ridethrough (LVRT) capability of WTs, emerging as an integral GC requirement. Despite current provision of LVRT in PMSG-based WTs, there is still likelihood of grid voltage drops leading to adverse effects in wind power plants. In this research, a peak current limiter has been designed for machine-side converter (MSC) of the PMSG-based WT to execute GC requirements in a reliable manner. This scheme is capable of preventing over-voltage across the dc link of back-to-back (BTB) converter and over-current in the grid-side converter (GSC). A dual current controller is utilised for regulating GSC positive-and negative-sequence components. A prominent feature of the proposed controller is its simplicity and applicability to available BTB control systems. On the other hand, the WT mechanical system operates as a storage device during voltage drops, eliminating the need for installing external apparatus such as energy storage systems and braking choppers across the dc-link. Simulation results conclude the reliable operation of the WT equipped with MSC current limitation scheme during grid faults.

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