Pilot Microgrids

F6. CESI RICERCA DER Test Facility (DER-TF)

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It consists in a LV microgrid, connected to the MV grid by means of a 800 kVA transformer.
It is constituted by several generators with different technologies (renewable and conventional), controllable loads and storage systems. DER-TF can provide electricity to the main grid with a maximum power of 350 kW.
The following distributed energy resources are available at the present time:

• a hybrid renewable energy system consisting of a photovoltaic plant (10 kWP), a lead-acid storage system, a diesel engine coupled with an asynchronous generator (7 kVA), a simulated asynchronous wind generator (8 kVA)
• five PV fields of different technologies for a total nominal power of 14 kW;
• a solar thermal plant with a parabolic dish and a Stirling engine (10 kW);
• a ORC CHP system fuelled by biomass (10 kWE, 90 kWTH);
• a CCHP plant with a gas microturbine (105 kWE, 170 kWTH, 100 kWRE);
• a Vanadium Redox Battery (42 kW, 2 hours);
• a Lead Acid battery system (100 kW, 1 hour);
• two high temperature Zebra batteries (64 kW, 30 minutes);
• a high speed flywheel for Power Quality (100 kW, 30 seconds);
• a controllable three-phase resistive-inductive load (100 kW + 70 kVAR);
• a capacitive load and several R/L loads with local control (150 kVAR).

All these DERs are connected to the microgrid by mean of a configuration and interconnection board that allows the microgrid operator to change the interconnections of DERs manually or by mean of remote commands from a computer. In this way it's possible obtaining different grid topologies: radial grids and also meshed configurations. There's also the opportunity to extend feeders till one kilometre.

By the end of 2008, a low voltage DC microgrid will be implemented and directly connected to the main microgrid of DER-TF, as well as a superconductor current limiter. During 2008, into the framework of MORE-microgrids project, a bi-directional three phase inverter (200 kVA), provided by I-Power, will be commissioned and tested

The interconnection board and all the DERs are provided with electrical measure equipments, constituting an high-speed Data Acquisition System (DAS), that has been set up to collect and analyze the experimental data derived from the field test.

A Communication system has been developed with different technologies: LAN Ethernet, Wireless and Power Line. A supervision and control infrastructure (URA) has been also implemented, providing several services:

• Interface with distributed resources (equipped with their local control systems): the control system gets measurement and sends commands and set-points
• Archive functions: data storage and retrieval, in order to permit further analysis
• Standard TCP/IP interface towards optimisation applications.

Optimisation procedures shall get data and send commands using a communication interface library (API) to exchange information with URA, trough standard TCP/IP interface. This communication library will be supplied, in order to be integrated in a generic optimisation application. Availability of the library and use of such a standard permits:

• Testing both from local and remote laboratories, thanks to the Internet communication.
• Remote testing of communication and SW optimisation procedures before carrying out tests on the real facility.
• Remote access from different users, where specific profiles could be set. For example, depending on nature of research activity or working phase, some users could only read data from generators, while others may send command to a sub-set of resources.

A further improvement could be represented by a standard procedure to set algorithms into the optimisation layer, for example by means of state-transition diagrams as in Matlab Stateflow© library.

The CESI RICERCA DER Test Facility is a complete and well-structured system with different generators, storage systems and loads that well reproduces a real microgrid, allowing researchers to develop studies and experimentations on DERs. Within the proposed project, CESI RICERCA DER Test facility will be used to perform several different experimentations, beginning with tests on I-Power Inverter operation, continuing with tests on advanced algorithms, developed during MORE-microgrids project.