Search

Estimation of amplitude, instantaneous phase, and frequency of a single-phase grid voltage signal are studied in this letter. The proposed approach uses a novel circular limit cycle oscillator (CLO) coupled with a frequency-locked loop. Due to the nonlinear structure of the CLO, the proposed frequency adaptive CLO technique is robust against various perturbations faced in the practical settings, e.g., the discontinuous jump of phase, frequency, and amplitude. The global stability analysis of the CLO and local stability analysis of the frequency adaptive CLO are performed. Experimental results demonstrate the effectiveness of the proposed technique over a very recent technique proposed in the literature. [ABSTRACT FROM AUTHOR]

Accurate and fast estimation of single-phase grid voltage phase and frequency has the potential to improve the performances of various control and monitoring techniques used in electric power systems. This letter applies an adaptive sliding mode observer for frequency and phase estimation. The observer is simple, easy to tune, and suitable for real-time implementation. The proposed adaptive observer can be considered as an alternative to a phase-locked loop (PLL) with better performance. dSPACE-based experimental results are given to show the effectiveness and performance improvement of the proposed approach with respect to two other advanced PLL techniques, namely, pseudolinear enhanced PLL and second-order generalized integrator-frequency locked loop. [ABSTRACT FROM AUTHOR]

This paper presents the design, development, control, and supervision of a hardware-based laboratory multiterminal-direct-current (MTDC) testbed. This work is a part of the TWENTIES (transmission system operation with large penetration of wind and other renewable electricity sources in networks by means of innovative tools and integrated energy solutions) DEMO 3 European project, which aims to demonstrate the feasibility of a dc grid through experimental tests. This is a hardware-in-the-loop dc system testbed with simulated ac systems in real-time simulation; the dc cables and some converters are actual, at laboratory scale. The laboratory-scale testbed is homothetic to a full-scale high-voltage direct-current (HVDC) system: electrical elements are the same in per unit. The testbed is supervised by a supervisory control and data acquisition system based on PcVue. A primary control-based droop control method to provide dc grid power balance and coordinated control methods to dispatch power as scheduled by a transmission system operator are implemented. Since primary control acts as converter level by using local measurements, a coordinated control is proposed to manage the dc grid power flow. The implemented system is innovative and achievable for real-time real-world MTDC-HVDC grid applications. [ABSTRACT FROM PUBLISHER]