Frequency-Adaptive Modified Comb-Filter-Based Phase-Locked Loop for a Doubly-Fed Adjustable-Speed Pumped-Storage Hydropower Plant under Distorted Grid Conditions

Abstract

Abstract:The control system of a doubly-fed adjustable-speed pumped-storage hydropower plant needs phase-locked loops (PLLs) to obtain the phase angle of grid voltage. The main drawback of a comb-filter-based phase-locked loop (CF-PLL) is the slow dynamic response. This paper presents a modified comb-filter-based phase-locked loop (MCF-PLL) by improving the pole-zero pattern of the comb filter, and gives the parameters' setting method of the controller, based on the discrete model of MCF-PLL. In order to improve the disturbance resistibility of MCF-PLL when the power grid's frequency changes, this paper proposes a frequency-adaptive modified, comb-filter-based, phase-locked loop (FAMCF-PLL) and its digital implementation scheme. Experimental results show that FAMCF-PLL has good steady-state and dynamic performance under distorted grid conditions. Furthermore, FAMCF-PLL can determine the phase angle of the grid voltage, which is locked when it is applied to a doubly-fed adjustable-speed pumped-storage hydropower experimental platform.

Hybrid Pumped Hydro Storage Energy Solutions towards Wind and PV Integration: Improvement on Flexibility, Reliability and Energy Costs

“…Thus, a brief economic analysis was conducted, using key financial parameters such as basic payback period (BPP), net present value (NPV) and internal rate of return (IRR) presented in Equations (5)-(7) [40,41].…”

“…As renewable energy investments represent a significant subset of the infrastructure sector, where PV and wind power investments have already become well established in the asset allocations of institutional investors, hydropower, by contrast, has a more difficult investment opportunity, since it requires significantly higher up-front investment per capacity unit, making it less scalable than wind power or photovoltaic plants [39][40][41][42]. Although, operating pumped-storage power plants is economically viable because electricity can be produced and sold depending on spot market prices, the technical know-how required for hydropower investments is more challenging since the success depends not only on technical and structural components but also on active management.…”

An Efficient Hybrid Filter-Based Phase-Locked Loop under Adverse Grid Conditions

“…Imbalances and frequency fluctuations in the grid voltage are caused by sudden failure in the grid and sudden change of grid load [1,2]. Thus, to achieve a quick and accurate of estimation of grid voltage phase under adverse grid conditions such as grid voltage imbalance and distortion is an issue of focus in the field of new energy grid-connections [3,4].…”