The utility grid challenge is to meet the current growing energy demand. One solution to this problem is to expand the role of microgrids that interact with the utility grid and operate independently in case of a limited availability during peak time or outage. This paper proposes, for urban areas, a building integrated photovoltaic (BIPV) primarily for self-feeding of buildings equipped with PV array and storage. With an aim of elimination of multiple energy conversions, a DC network distribution is considered. The BIPV can supply a tertiary building at the same time as PV array may produce power through a hierarchical supervision able to exchange messages with the smart grid and metadata. The hierarchical control is designed as an interface to expand the system ability for advanced energy management control having regard to the grid availability and user's commands. It consists of four layers: human-machine interface, prediction, cost management, and operation. The operation layer, implemented in an experimental platform, takes into account the grid supply power limits and constrains the DC load. The experimental results validate the approach that may be a solution for the future smart grid communication between BIPV and utility grid.

Aiming at photovoltaic (PV)-storage urban building integrated system, this paper proposes a DC microgrid with multi-layer control and smart grid communications. The paper focuses on power balancing, with load shedding and PV constrained production, and takes into account the grid availability and grid vulnerability by smart grid messages. The system behavior modeling by MATLAB Stateflow leads to the whole control strategy design, which concerns the power balancing and imposed power limits by the utility grid, while providing interface for energy management. Experimental results evaluate the feasibility of the proposed control strategy. As further development of this control design, an intelligent multi-layer supervision is suggested. This supervision, able to exchange data with the smart grid, deals with the end-user demand, forecast of photovoltaic production, prediction of load consumption, and energy management. The major technical contribution of this paper is linked to the proposed control design that permits better DC microgrid integration (avoids undesired injection, mitigates fluctuations in grid power, reduces grid peak consumption) and provides possibility to reduce the negative impact on the utility grid thanks to the supervision interface. The power balancing control interface provides possibility for advanced energy management with low speed communication.

In the context of distributed generation and renewable energy penetration toward smart grid, grid-connected inverter with LCL filter has drawn many attentions, whose current control conventionally requires several sensors to realize active damping and grid synchronization. In this paper, a novel full status observation strategy based on extended state observer (ESO) is proposed using inverter current feedback only and without grid voltage sensor. The proposed observation strategy contains observation and transformation process. Unlike conventional Luenberger observer, by using ESO, the system parameters do not appear in observation process, thus the observer dynamics and parameter mismatch error can be separately handled, providing more robust observation dynamics during parameter variation. Parameter mismatch study was carried out, and it is found that purposely choosing the observer parameters smaller than the real value can achieve relatively low estimation error and a large adaption range for parameter variation. The proposed observation strategy is simple to implement, without the need of expert knowledge-based parameter tuning such as pole placement. Experimental tests validated that the proposed observation-based control is able to give satisfactory performance in both dynamic and steady states, as well as adaption for system parameter variation.