Direct voltage fluctuations due to the presence of relatively large DC reactors (as an essential part HVDC breakers), lack inertia, and unwanted frequency in AC side grids, have major consequences on stability HVAC/HVDC grids. The use Power System Stabilizer (DC-PSS) can damp eliminate oscillations caused by reactors. However, DC-PSS cannot address issues inertia fluctuations. A method improve ...

In this paper, the optimal design of supplementary controller parameters of a unified powerflow controller(UPFC) for damping low-frequency oscillations in a weakly connected systemis investigated. The individual design of the UPFC controller, using hybrid particle swarmoptimization and gravitational search algorithm (PSOGSA)technique under 3 loadingoperating conditions, is discussed. The effect...

This paper investigates the relationship between frequency support by voltage-source converter based high-voltage direct current (VSC-HVDC) systems and deloaded wind power operation considering stability constraints. The is incorporated as additional constraints in optimal flow (OPF) analysis. reserve capacity of plants should be provided for support, which requires output suppression during st...

The cascaded hybrid LCC-MMC inverter is considered as a feasible option to mitigate the commutation failure problem of conventional LCC-HVDC while maintaining bulk power transmission capability. However, coupling between different types converters may result in instability when integrates with weak AC systems. This paper establishes small-signal model based HVDC system and validates against PSC...

VSC HVDC will be the most important approach for transmitting the power of large-scale offshore wind power plant in the near future. In recent literature, the feasibility of using hybrid type HVDC for offshore wind transmission has been discussed. A hybrid HVDC system has at one line commutated converter (LCC) at mainland and one voltage source converter (VSC) at offshore platform, which may in...

High Voltage Direct Current (HVDC) Transmission systems traditionally employ PI controllers with fixed proportional (P) and integral (I) gains Kp and Ki respectively. Although such controllers are robust and simple, they are not easily optimized to obtain the best performance under all conditions. In the field of intelligent control systems, fuzzy logic control and artificial neural network bas...

Existing mechanical HVDC breakers are capable of interrupting HVDC currents within several tens of milliseconds, but this is too slow to fulfill the requirements of a reliable HVDC grid. HVDC breakers based on semiconductors can easily overcome the limitations of operating speed, but generate large transfer losses, typically in the range of 30 percent of the losses of a voltage source converter...

Impedance measurements have been widely used with the Nyquist plot to estimate the stability of interconnected power systems. Being a black-box method for equivalent and aggregated impedance estimation, its use for the identification of sub-components bandwidth is not a straightforward task. This paper proposes a simple method that will enable to identify the specific part of the equivalent imp...