Change search
ReferencesLink to record
Permanent link

Direct link
Wide-Area measurement system-based subspace identification for obtaining linear models to centrally coordinate controllable devices
KTH, School of Electrical Engineering (EES), Electric Power Systems.
KTH, School of Electrical Engineering (EES), Electric Power Systems.ORCID iD: 0000-0002-8189-2420
2011 (English)In: IEEE Transactions on Power Delivery, ISSN 0885-8977, E-ISSN 0885-8877, Vol. 26, no 2, 988-997 p.Article in journal (Refereed) Published
Abstract [en]

The contribution of this paper is the application of subspace system identification techniques, to derive a low-order black-box state-space model of a power system with many controllable devices using global signals. This model is a multiinput, multioutput open system model describing the power oscillatory behavior of the power system. The input signals are the controllable setpoints of the controllable devices, the output signals are the speed of selected generators measured by a wide-area measurement system. This paper describes how to achieve and preprocess the data to use subspace techniques to estimate and validate to finally assign an accurate model. This new approach can be used directly to design a central coordinating controller for all of the relevant controllable devices, with the aim to increase the damping of the modes in the system. Previously presented methods use local measurements or output signals dependent on the actual operational point. The benefit of the presented method is that the used output signals are independent of the system state. This makes it possible to use state-feedback control to combine the controllable devices to coordinately damp the modes. The presented method is applied in the CIGRÉ Nordic 32-bus system including two HVDC links. The case study demonstrates that accurate low-order state-space models can be estimated and validated by using the described method to accurately model the system's power oscillatory behavior.

Place, publisher, year, edition, pages
2011. Vol. 26, no 2, 988-997 p.
Keyword [en]
Flexible ac transmission system (FACTS) devices, Generators, HVDC, HVDC transmission, N4SID, Noise, Oscillators, Power system dynamics, Power system stability
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
URN: urn:nbn:se:kth:diva-30623DOI: 10.1109/TPWRD.2010.2094628ISI: 000288758400054ScopusID: 2-s2.0-79953200099OAI: diva2:401158
QC 20110302Available from: 2011-03-01 Created: 2011-03-01 Last updated: 2012-01-11Bibliographically approved
In thesis
1. Coordinated Control of HVDC Links in Transmission Systems
Open this publication in new window or tab >>Coordinated Control of HVDC Links in Transmission Systems
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Dynamic security limits the power transfer capacity between regions and therefore has an economic impact. The power modulation control of high-voltage direct current (HVDC) links can improve the dynamic security of the power system. Having several HVDC links in a system creates the opportunity to coordinate such control, and coordination also ensures that negative interactions do not occur among the controllable devices.

This thesis aims to increase dynamic security by coordinating HVDC links, as an alternative to decreasing the transfer capacity. This thesis contributes four control approaches for increasing the dynamic stability, based on feedforward control, adaptive control, optimal control, and exact-feedback linearization control. Depending on the available measurements, dynamic system model, and system topology, one of the developed methods can be applied. The wide-area measurement system provides the central controller with real-time data and sends control signals to the HVDC links.

The feedforward controller applies rapid power dispatch, and the strategy used here is to link the N-1 criterion between two systems. The adaptive controller uses the modal analysis approach; based on forecasted load paths, the controller gains are adaptively adjusted to maximize the damping in the system. The optimal controller is designed based on an estimated reduced-order model; system identification develops the model based on the system response. The exact-feedback linearization approach uses a pre-feedback loop to cancel the nonlinearities; a stabilizing controller is designed for the remaining linear system.

The conclusion is that coordinating the HVDC links improves the dynamic stability, which makes it possible to increase the transfer capacity. This conclusion is also supported by simulations of each control approach.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2011. x, 51 p.
Trita-EE, ISSN 1653-5146 ; 2011:004
coordinated control, dynamic security, exact-feedback linearization, feedforward control, HVDC poser modulation
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
urn:nbn:se:kth:diva-30625 (URN)978-91-7415-875-5 (ISBN)
Public defence
2011-03-24, Sal K2, Teknikringen 28, Entréplan, KTH, Stockholm, 10:00 (English)
QC 20110302Available from: 2011-03-02 Created: 2011-03-01 Last updated: 2011-03-02Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textScopus

Search in DiVA

By author/editor
Eriksson, RobertSöder, Lennart
By organisation
Electric Power Systems
In the same journal
IEEE Transactions on Power Delivery
Other Electrical Engineering, Electronic Engineering, Information Engineering

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 201 hits
ReferencesLink to record
Permanent link

Direct link