Investigation of progressive settlement of sandy cobble strata for shield tunnels with different burial depths

Local buckling characteristic of hollow π-type steel-concrete composite support in hilly-gully region of loess tunnel

Prediction of tunnelling induced ground movement in clay using principle of minimum total potential energy

Failure mechanical behaviors and prevention methods of shaft lining in China

Experimental study on the collapse evolution law of unlined tunnel in Boulder-Cobble mixed formation

Centrifuge modelling of tunnelling below existing twin tunnels with different types of support

With proportions of wind power and other clean energies generation increasing rapidly, it's of great significance to incorporate them into primary frequency regulation (PFR) for improving dynamic performance of system frequency. This paper firstly analyzes issues relevant to PFR in high-proportion clean energy (HPCE) system, including status of PFR in actual power grid with HPCE and necessity for wind power to extensively participate in PFR. Then, a system frequency response (SFR) model with multienergy is built, and a process for setting PFR parameters of wind power which include deadband, limiting amplitude and droop coefficient is proposed. Finally, based on a certain operation mode of Yunnan Power Grid, a series of simulation using the proposed process are carried out. By constraints of required maximum of system frequency deviation and Rate of Change of Frequency (RoCoF) under various possible operation conditions, recommended values for deadband, limiting amplitude and droop coefficient are given.

Parameters Setting for Primary Frequency Regulation of Wind Power in High-Proportion Clean Energy System

In this paper we present here a strategy about wind turbines participating in primary frequency regulation (PFR) to improve low frequency conditions of Yunnan Power Grid in China. We first establish a system frequency response (SFR) model including multiple power sources and frequency limit controller (FLC) of DC system. Then, we propose a process to optimize parameters of wind turbines PFR from the perspective of improving the action of FLC. Simulation results show that the wind turbines participating in FPR with using inertia control, which can quickly suppress the frequency peak of the system, effectively reduce the number of actions of Frequency Limit Controller, and avoid the frequency secondary drop in hydro-dominated system with Frequency limit controller.

Research of Inertial Control Strategy of Wind turbines under Low Frequency Situation of Hydro-dominated System

A piecewise linearization model is developed for the analysis of ultra-low frequency oscillation, taking the nonlinearity of governor deadband and the automatic generation control (AGC) into considerations. Firstly, the ultra-low frequency oscillations occurred in actual power grids are discussed in depth. Then, based on the piecewise linearization model developed, the AGC-excited frequency mode is calculated and key factors that influence the frequency stability are analyzed using the eigenvalue approach. Results show that the governor deadband introduces a frequency mode that likely to be excited by large frequency bias coefficient B of the AGC system. To avoid this frequency oscillation, it is advised that B should be properly tuned under the situation when only the secondary frequency regulation is activated.

Kehan Zeng

Papers

Centrifuge modelling of tunnelling below existing twin tunnels with different types of support

Parameters Setting for Primary Frequency Regulation of Wind Power in High-Proportion Clean Energy System

Research of Inertial Control Strategy of Wind turbines under Low Frequency Situation of Hydro-dominated System

Analysis of Frequency Oscillation Caused by AGC in Hydro-Dominant Power Grids using Piecewise Linearization Method