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This paper presents various control strategies to improve operations in two interconnected areas connected by a VSC‐HVDC transmission line. The main focus is on designing a central control system (CCS) that coordinates control units in both areas. In area 1, an AC voltage control unit is connected to the CCS. In area 2, three control units including a load power control unit, a fault detection unit, and an AC voltage control unit are also connected to the CCS. The CCS receives inputs from these units and generates commands for the DC voltage and active/reactive power control units on both sides of the DC line. The first proposed strategy addresses permanent voltage drops caused by load fluctuations in area 2. It adjusts the transmitted power from area 1 based on voltage variations in area 2. The second strategy focuses on mitigating faults in area 2 by injecting active and reactive power from area 1 during such events. The third strategy resolves transient voltage oscillations in both areas by controlling the reactive power of stations on either side of the DC line. Simulations using MATLAB‐SIMULINK demonstrate that these mechanisms successfully achieve their objectives. [ABSTRACT FROM AUTHOR]

This paper presents a control mechanism on high voltage direct current (HVDC) transmission line for frequency/voltage regulation, fault ride through (FRT) capability, and cyber‐attack/fault detection. The network under study consists of two areas with different frequencies that are connected through one 300 km HVDC line. The proposed control system regulates the frequency in both areas by managing power through HVDC line. The converters on both sides of HVDC line are controlled to handle faults on the DC and AC sections as well as improving fault ride through capability. The control strategies are implemented and operated depending on fault/cyber‐attack type and behaviour. In this respect, the control mechanism may change the firing angle of converters, switch their operating mode from rectifier to converter and vice‐versa or even block the converters. The proposed paradigm successfully distinguishes between the cyber‐attacks and faults. The simulations in MATLAB software validate that the proposed mechanism realizes all the objectives and the cyber‐attacks are completely identified and separated from the faults. [ABSTRACT FROM AUTHOR]

A resilient control system in the island microgrid including AC and DC buses is designed here. The DC bus is supported by fuel cell, solar cell and battery and the AC bus is equipped with diesel generator and wind turbine. The AC bus is sectionalized into three sub‐buses that enables to continue operation when one section is not functioning. The connection between DC and AC buses is made by two parallel three‐phase lines each line made by three single‐phase inverters. The objectives are to eliminate the harmonics, the unbalanced load management, dealing with outage of resources and short circuits, providing backup strategies and supplying critical loads under all events. The simulations are performed by MATLAB/Simulink. It is demonstrated that the resilient control technique can achieve all the defined purposes at the same time. The harmonics are eliminated, the unbalanced load issues are dealt with and the microgrid has sufficient resilience against outages and faults. [ABSTRACT FROM AUTHOR]