Wednesday, 9 September 2009

PV plant control

New versatile modular controller for solar photovoltaic plants
Carlo Gavazzi’s new Eos-Array controller enables efficient running of PV plants to help meet the growing demand for green energy

Carlo Gavazzi has announced a new versatile, reliable management and control system targeting small to medium or high power solar photovoltaic (PV) plants. The new controller is designed to enable the plants to meet growing demand for clean sources of energy by maintaining efficient operation, maximising performance and strengthening the Return on Investment.

Easy to install and configure, the new Eos-Array comprises individual modular elements that, when interacting with one another, provide a complete and independent control solution that gathers accurate and dependable data to ensure effective information management. The core component is the VMU-M which performs local bus management of measuring units and I/O modules. The VMU-M assigns the proper local unit address automatically and gathers all local measurements from the VMU‑S and VMU‑P, simultaneously connecting with the external world through VMU-O modules.

It has a modular design allowing the control to be scaled up or down according to requirements and budgets. A single master VMU-M can control 15 Eos modules on its local bus; including up to seven VMU-O I/O modules and one VMU-P unit. With no auxiliary bus wiring, the system is simple to install and straightforward to expand. Further cost saving is provided by the integrated string fuse protection and modularity also improves overall system reliability. String efficiency and inverters are controlled locally enabling operators to rapidly isolate faults, failures and inefficiencies.

Each VMU-O provides two PV panel temperature inputs and two relay outputs to manage alarms (such as the integrated anti-theft system) and external loads (such as lighting and PV washing systems). The VMU-S measures DC output from the PV panel. VMU-P collects relevant environmental data (through external sensors) such as wind speed, air temperature and irradiation. Eos-ArraySoft can download the Eos-Array system memory to the PC, for scheduled or on-demand plant efficiency calculations and alarm analysis.

A typical 50kW plant would use one VMU-M unit for data logging and local bus management, ten VMU-S units for string control (50kW total for 228x220W PV panels, 12.5A/400V single string), one VMU-O for I/O management and one VMU-P for environment measurements. Eos-ArraySoft software is installed in a local PC to provide data collection and historical analysis.

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