The introduction of generators in distribution grids, possibly together with storage systems, could cause a substantial change in grid operational practice: currently a rising idea proposes to treat generators and even loads as distributed resources that are able to supply services to the grid and accept on-line requests. To emphasise the advantages of Distributed Generation (DG) it is necessary to face the problem with a system approach. In this work both services coming from each generator and deriving from the co-ordination of different resources have been investigated. A complex master-slave configuration has been discarded in order to avoid the necessity of fast communication and control actions. Instead a model based on a centralised dispatcher and plug-and-play functionality for generators has been chosen. For that purpose, a distinction is made between fast transient dynamics, due to uncontrollable load changes, and slow modifications of the system conditions, due to increase/decrease of loads during a day, a week or a month. Individual generators have been requested to give response to fast and unpredictable transient dynamics, i.e. to participate to voltage and frequency regulations, harmonic compensations and phase balancing, while the central dispatcher has been requested to deliver proper set-points in order to allow each generator to offer its services in an appropriate way, either for the actual and the foreseen grid conditions. To realise voltage and frequency regulations, a droop control algorithm has been designed and implemented on board of some generators coupled to the grid by inverter technology. In that scenario each machine, working in parallel with the others, takes on part of the regulation according to its possibilities. The focus of the paper is on the architecture of the system and on the modules that a centralised dispatcher has to incorporate. The main topics are: the short-term forecasts of the power produced by renewable energy, the short-term forecasts of uncontrollable low voltage distribution loads, the state estimation of LV grid, the use of load flow, the definition of objective functions for economical optimisation, the sub-grid regulation and the Test Facility set up in CESI, where some experiments have been done. The conclusion of the activity is that the high penetration of DG could become an opportunity rather than be considered as a problem. The distributed resources could be used to control the voltage profiles, the power flows, the separations from the main distribution grid and islanding operations. The activities was supported by a National Research Project named GENDIS 21- Distributed Generation for the Improvement of Power Quality and Environment.
A. Bertani, A. Borghetti, C. A. Nucci, M. Paolone, S. Massucco, A. Morini F. Silvestro, et al. (2006). Management of Low Voltage Grid with High Penetration of Distributed Generation: concepts, implementations and experiments. PARIS : CIGRE.
Management of Low Voltage Grid with High Penetration of Distributed Generation: concepts, implementations and experiments
BORGHETTI, ALBERTO;NUCCI, CARLO ALBERTO;PAOLONE, MARIO;
2006
Abstract
The introduction of generators in distribution grids, possibly together with storage systems, could cause a substantial change in grid operational practice: currently a rising idea proposes to treat generators and even loads as distributed resources that are able to supply services to the grid and accept on-line requests. To emphasise the advantages of Distributed Generation (DG) it is necessary to face the problem with a system approach. In this work both services coming from each generator and deriving from the co-ordination of different resources have been investigated. A complex master-slave configuration has been discarded in order to avoid the necessity of fast communication and control actions. Instead a model based on a centralised dispatcher and plug-and-play functionality for generators has been chosen. For that purpose, a distinction is made between fast transient dynamics, due to uncontrollable load changes, and slow modifications of the system conditions, due to increase/decrease of loads during a day, a week or a month. Individual generators have been requested to give response to fast and unpredictable transient dynamics, i.e. to participate to voltage and frequency regulations, harmonic compensations and phase balancing, while the central dispatcher has been requested to deliver proper set-points in order to allow each generator to offer its services in an appropriate way, either for the actual and the foreseen grid conditions. To realise voltage and frequency regulations, a droop control algorithm has been designed and implemented on board of some generators coupled to the grid by inverter technology. In that scenario each machine, working in parallel with the others, takes on part of the regulation according to its possibilities. The focus of the paper is on the architecture of the system and on the modules that a centralised dispatcher has to incorporate. The main topics are: the short-term forecasts of the power produced by renewable energy, the short-term forecasts of uncontrollable low voltage distribution loads, the state estimation of LV grid, the use of load flow, the definition of objective functions for economical optimisation, the sub-grid regulation and the Test Facility set up in CESI, where some experiments have been done. The conclusion of the activity is that the high penetration of DG could become an opportunity rather than be considered as a problem. The distributed resources could be used to control the voltage profiles, the power flows, the separations from the main distribution grid and islanding operations. The activities was supported by a National Research Project named GENDIS 21- Distributed Generation for the Improvement of Power Quality and Environment.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
