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• The 1-mode and 0-mode transient voltage integrals are analyzed in the pure-fault network. • A single-end protection method using adaptive thresholds is proposed for the MMC-HVDC grid. • The proposed method is sensitive to single-pole high-resistance faults and suitableness for weak boundaries. For the bipolar modular multilevel converter-based high voltage DC (MMC-HVDC) grids, single-end protection methods suffer from low sensitivity in detecting high-resistance faults (HRF). The performance further deteriorates in a weak boundary configuration. To improve the deficiency, this paper proposes a protection method with adaptive thresholds. First, an MMC simplified circuit, an internal fault analysis network, and a DC bus fault analysis network are presented in pure-fault networks. The integral characteristics for 1-mode and 0-mode voltage fault components are studied under different locations. It is discovered that the relative size for two modal voltage integrals is different for internal faults and DC bus faults. A new form of mathematical morphology filter is proposed to select the required integral time. With 1-mode and 0-mode voltage integral, the fault identification method using adaptive threshold is proposed as well as its setting method. Simulations of a four-terminal MMC-HVDC system built in PSCAD/EMTDC verify the effectiveness of the proposed method. The method can fast detect internal single-pole HRFs of different locations and operate reliability under active power reversal, AC-side faults, and noise interference. Compared to some existing methods, the proposed method can detect high-resistance faults under weak boundary configurations. [ABSTRACT FROM AUTHOR]

Highlights: [•] The Ibrahim time domain (ITD) method is able to identify the frequencies, damping and mode shapes of the interarea modes. [•] A zero-phase low-pass filter will greatly improve the performance of the ITD method in the presence of measurement noise. [•] The ITD method is much faster than the stochastic subspace identification (SSI) method in estimating interarea modes. [•] When the input ring-downs are contaminated by ambient noise, the ITD method performs better than the SSI method. [•] The ITD method may still give quite acceptable estimation results when only limited input signals are available. [ABSTRACT FROM AUTHOR]

Wide-area measurement systems enable the wide-area damping controller (WADC) to use remote signals to enhance the small signal stability of large scale interconnected power systems. System operating condition variations and signal transmission time delays are the major factors to worsen the damping effect and even deteriorate the system stability. This paper proposes a novel measurement-based adaptive wide-area damping control scheme using oscillation mode prediction and system identification techniques. These techniques adjust the parameters of WADC as well as the time delay compensation in an online environment. To achieve fast online implementation, an identified high order multi-input multi-output (MIMO) model is deformed into a low order single-input single-output (SISO) model according to the residue of MIMO model. The SISO model can accurately represent the power system dynamics in the form of a transfer function, capturing the dominant oscillatory behaviors in the frequency range of interest. Moreover, the WADC has been implemented on a hardware test-bed (HTB) by adding its output signal to the excitation system of a selected generator. The effectiveness of the proposed measurement-based adaptive WADC has been demonstrated in a two-area four-machine system on the HTB under various disturbance scenarios. [ABSTRACT FROM AUTHOR]