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Advanced controllers have been widely introduced in power system-related research to alleviate the uncertainties of renewable sources. The performance of the controllers should be verified in a realistic environment before the controllers are used in practical applications. This study focuses on voltage regulation of wind farms in voltage drop cases where communication failures occur and discusses modifications done on the online wind farm management system. The modified management system is designed to respond to a voltage drop when the outer reference signal from the upper-level controller is absent due to technical problems, especially communication errors. Such a situation has not been considered in most of the management systems in the literature. The predictable situations in real fields have been further verified under the hardware-in-the-loop simulation environment RTDSTM. During communication failure, the proposed method can respond automatically to voltage recovery, along with a designed objective function. A comparative analysis of actual control modes was also conducted to prove the relevance and effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

This study proposes a novel decentralized operation strategy for a multi-terminal direct current (MTDC) link system to control the power flow between interconnected distribution networks. The proposed strategy is divided into two stages. First, by applying a curve-/surface-fitting technique to the network topology data, the formulas for the voltage and total line losses in the network are derived. Subsequently, the active/reactive power set-points of the MTDC link are optimized to minimize the network losses and balance the injected power from the upstream grid. The optimization model with a quadratically constrained quadratic problem is relaxed as a second-order constrained programming model using the proposed substitution process. The proposed strategy is implemented solely based on the information at the point of common coupling of the MTDC link and does not require the acquisition of any real-time data related to the distributed generator output and load demand. The effectiveness of the proposed method is verified by comparing it with a conventional centralized operation method using modified IEEE-33 test networks. [ABSTRACT FROM AUTHOR]