Power Oscillation Damping Using Converter- Interfaced Generators under Constrained Active and Reactive Powers

Abstract

Low-frequency oscillations are an inherent phenomena in transmission networks and renewable energy plants should be configured to damp them. Commonly, a centralised controller is used in PV plants to coordinate PV generators via communication channels. However, the communication systems of PV plants introduce delays of a stochastic nature that degrade the performance of centralised control algorithms. Therefore, controllers for oscillation damping may not operate correctly unless the communication channel characteristics are not considered and compensated. In this paper, a centralised controller is proposed for the oscillation damping that uses a PV plant with all the realistic effects of communication channels taken into consideration. The communication channels are modelled based on measurements taken in a laboratory environment. The controller is designed to damp several modes of oscillation by using the open-loop phase shift compensation. Theoretical developments were validated in a laboratory using four converters acting as two PV inverters, a battery and a STATCOM. A real-time processing platform was used to implement the centralised controller and to deploy the communication infrastructure. Experimental results show the communication channels impose severe restrictions on the performance of centralised POD controllers, highlighting the importance of their accurate modelling and consideration during the controller design stage.

Power oscillation damping method suitable for network reconfigurations based on converter interfaced generation and combined use of active and reactive powers

“…It has already been shown that this design method provides a system damping that is close to the optimal value [29]. Also, as the design is based on open-loop characteristics, the calculation of the compensator parameters can be easily automatised.…”

“…2, respectively. In [29], it has been shown that the criteria from (10) can be met by setting phases to zero for two open-loop functions separately:…”

“…To meet the objectives presented in (12), each controller (C P (s) and C Q (s)) should compensate the phase of its corresponding open-loop system at the oscillation frequency [29]. Taking into account multiple oscillation frequencies and changes caused by network reconfiguration, this criteria can be defined as (only the active power loop is shown):…”

“…These limits are changing over time based on the network operating point and available energy from the primary energy source. For simplicity, these limits are kept constant in this work (see [29] for more details).…”

Centralised Multimode Power Oscillation Damping Controller for Photovoltaic Plants With Communication Delay Compensation

“…The POD controller will be designed by using the open-loop phase compensation method [27]. A simplified version of this method was previously presented in [28]. It was shown that the controller of each power loop should be designed separately and compensate the open-loop phase at the oscillation frequency of the corresponding plant.…”