Time: Thursday, April 27, 2017
Venue: Room 625, Building No.30, Wushan Campus
Opening Ceremony 15:00-15:10
Title: Smart control schemes for VSC-HVDC Transmission Systems 15:10-16:00
Speaker: Dr. Zhu Jiebei(National Grid, UK)
Renewable power generation and voltage source converter (VSC) based high voltage direct current (HVDC) technologies are growing globally with an unprecedented speed. The nature of these technologies are power electronics interfaced non-synchronous generation which synchronises with the AC grids using phase locked loops. Conventional control schemes for NSG using phase locked loops decouple the mechanical inertia available behind VSC, meaning that for any grid rotor angle and frequency disturbance the VSC does not response to mitigate the instability. Also for many NSG such as wind, solar and VSC-HVDC the inertia stored in rotating mass of the other side is null or minimal. Therefore it will be challenging and costly for power system operators to contain frequency deviations following major faults in future NSG dominated power grid.
This talk will introduce a new control scheme termed Inertia Emulation Control (INEC) for VSC-HVDC and wind turbine generators (WTG) to enable an inertial response service. It utilises the energy stored in the DC link of capacitors and hence requires augmentation of the DC capacitance. The INEC allows a NSG system with a fixed capacitance to emulate a wide range of inertia constants(H) by specifying the amount of permissible DC voltage variation. The INEC provided at the inverter terminals of the HVDC links has no impact on the rectifier-side offshore wind power system. Simulations verify that the INEC for NSG is capable of interacting with connected generators, counteracting, and damping generator rotor speed (and system frequency) changes. It allows the NSG system to contribute to both the damping of low-frequency oscillations, enhancement of the primary frequency control of the AC networks and consolidation of system fault ride-through capability.
Announced by School of Electric Power