System stability improvement through optimal control allocation in voltage source converter-based high-voltage direct current links

Abstract

Control of both active and reactive power in voltage source converter (VSC) based HighVoltage Direct Current (HVDC) links could be very effective for system stability improvement. The challenge, however, is to properly allocate the overall control duty among the available control variables in order to minimize the total control effort and hence allow use of less expensive converters (actuators). Here relative gain array (RGA) and residue analysis are used to identify the most appropriate control loops avoiding possible interactions.Optimal allocation of the secondary control duty between the two ends of the VSC HVDC link is demonstrated. Active and reactive power modulation at the rectifier end, in a certain proportion, turns out to be the most effective. Two scenarios, with normal and heavy loading conditions, are considered to justify the generality of the conclusions. Subspace-based multi-input-multi-output (MIMO) system identification is used to estimate and validate linearized state-space models through pseudo random binary sequence (PRBS) probing.Linear analysis is substantiated with non-linear simulations in DIgSILENT PowerFactory with detailed representation of HVDC links.

Control of multi-terminal HVDC networks towards wind power integration: A review

“…Hazra et al [53] analyse the selection of several measures and control signals in order to achieve the maximum effect on the transient response of the AC grids. Pipelzadeh et al [54] determine the most suitable control signals for the HVDC links to damp power oscillations, showing the potential of using active and reactive power simultaneously. In [55], a robust decentralised control is proposed using a homotopy approach to add various PSS active and reactive power loops with different input signals, improving reliability and robustness.…”

Impact analysis of variable generation on small signal stability

“…One of the most important aspects of system identification is the selection of the probing signal [17]. Firstly, the frequency spectrum needs to cover the frequency band of interest, and, secondly, the amplitude of the signal must be sufficiently high to excite the critical oscillatory modes without pushing the system into a nonlinear zone [18].…”

System stability improvement through HVDC supplementary Model Predictive Control

“…Various controlling schemes have been considered in the literature. Employing local or wide area data, centralized or de-centralized controllers and robustness of the controller has been the subject of the recent researches in this area [1,2,3].…”