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OSMOSE Grid-Forming performance assessment within multiservice storage connected to the transmission grid
Abstract
The European research project MIGRATE, and especially its Work Package 3 (WP3) demonstrated that grid-forming controls for some converters is a necessary condition to operate a system without synchronous machines with a sufficient level of reliability [1]. Despite the limited overcurrent capability of the converters, several control concepts showed their effectiveness to ensure the stable voltage source behaviour of parallel converters, even during transients on the grid, such as phase-jumps or three-phase faults. The main theoretical results have already been validated on real hardware in lab environment. However, until now, DC side dynamics, as well as unbalanced and disturbed AC grid conditions have often been overlooked. A step further toward standardisation of grid-forming converter should prove its technical feasibility taking into account those aspects. In the WP3 of the European research project OSMOSE, RTE builds upon the MIGRATE results to increase the maturity level of grid-forming converters. In concrete terms, RTE will install a demonstrator on its own network in August 2020: a one-Megawatt grid-forming inverter backed up with batteries (500kW for one hour) and ultra-capacitances (1MW for 10 seconds). Our previous work focused on the development of suitable DC side power sharing and energy management strategies and a negative sequence control using Matlab while considering an ideal network. In this work, we validate the latest version of the demonstrator control as will be implemented onsite with a more realistic grid model available in EMTP. Expected performance are observed: the ultra-capacitances smooth the battery power output and the overcurrent is limited. However, as the fault behaviour in grid codes was specified for grid following converter, additional work is required to make regulation and grid forming controls response compatible.
... One simple option consists in adding saturations to the cascaded proportional-integral (PI) inner control loops. Other authors have proposed to switch the control to a PLL-based current control during grid faults in order to keep the synchronism with the system while still limiting the current [1]. The main drawback of this method is the requirement of a complex algorithm for fault detection and triggering conditions setting. ...
... Once all the three steps are performed, the estimated AC voltage droop is applied at the output voltage following different strategies depending on the grid forming algorithm. Some grid forming controls have a virtual impedance per each phase [5], others control only in the voltage module [6], while the majority of them implement the algorithm in DQ reference frame [1,7,8]. ...
With an increasing capacity of inverter-based generation and with a 100% renewable energy power system on the horizon, grid forming converters have the potential to become the prevalent control mode in the grid. Thus, the correct performance of these devices is going to be crucial for system stability and security of supply. Most research related to the grid-forming control is focused on normal operating conditions, although significant effort has been devoted to current limitation strategies to ensure Low Voltage Ride Through (LVRT) capability. However, most contributions usually consider only balanced faults. This paper, proposes a new current limiting method based on the well-known threshold virtual impedance (TVI) that keeps the voltage source behaviour associated to the grid forming (GFM) capability, even when the current limit is reached, while reducing the voltage unbalance according to user-defined settings
... The current limitation is based on a Threshold Virtual Impedance (TVI) and the droop is reduced during its activation [6]. Previous works showed the stable association of the grid forming function with different DC side power sharing and energy management strategies [7] and a preliminary performance assessment on EMTP [8] anticipates proper behaviour with the connection grid. This section recalls main features and settings selected for the final control: ...
In the EU-funded project OSMOSE, RTE and Ingeteam installed a 1 MVA demonstrator to show the technical and economical viability of building a grid-forming function upon a commercially available hybrid energy storage system. In this paper we share the experimental results obtained in a power hardware in the loop test bench during the Factory Acceptance Test. We implemented a filtered droop control with a threshold virtual impedance (TVI) for current limitation. Performance assessment covered synchronisation, reference tracking and disturbance rejection, including low voltage ride-through, phase jumps and grid frequency variations, but also the behaviour under permanent unbalanced and distorted conditions. This demonstrator contributes to increase of the TRL of the grid forming function as the implemented control proved to be effective in providing frequency and voltage smoothing services while operating safely without oversizing and compiling with most of the current technical requirements.
Local Control for GridForming Converters : Experimental Validation
In the EU-founded project OSMOSE, RTE and Ingeteam will install a demonstrator (Ringolab) to show the technical and economical viability of building a grid-forming function upon a traditional energy storage system. Although main theoretical results have already been validated on real hardware in a laboratory environment within the framework of the MIGRATE project, a grid-connected demonstrator represents a step further toward the standardization of grid-forming converters. In this paper we present its technical description and we show stable association of the grid-forming control with different DC side power sharing and energy management strategies while considering a hybrid energy storage system.
Deliverable 3.1: Multi-service control algorithm for converters
- E Namor
- F Sossan
- R Cherkaoui
- M Paolone
E. Namor, F. Sossan, R. Cherkaoui, M. Paolone. "Deliverable 3.1: Multi-service control
algorithm for converters" (OSMOSE project, available online)
Grid-Forming control for Hybrid Energy Storage System in Unbalanced Conditions
- C Cardozo
- M Zubiaga
- G Denis
- T Prevost
- J J Valera
- Y Vernay
C. Cardozo, M. Zubiaga, G. Denis, T. Prevost, J. J. Valera, Y. Vernay. "Grid-Forming control for
Hybrid Energy Storage System in Unbalanced Conditions" (submitted to IFAC 2020, Berlin)
Application of Frequency-Dependent Network Equivalents for EMTP Simulation of Transformer Inrush Current in Large Networks
- Y Vernay
- B Gustavsen
Y. Vernay, B. Gustavsen, "Application of Frequency-Dependent Network Equivalents for
EMTP Simulation of Transformer Inrush Current in Large Networks", International
Conference on Power Systems Transients (IPST2013) in Vancouver, Canada July 18-20, 2013.
Implementation of a unified modelling between EMT tools for Network Studies
- B Bruned
- C Martin
- S Dennetière
- Y Vernay
B. Bruned, C. Martin, S. Dennetière, Y. Vernay, "Implementation of a unified modelling
between EMT tools for Network Studies", International Conference on Power Systems
Transients (IPST2017) in Seoul, Republic of Korea June 26-29, 2017