Control and management in smart grids are facing many challenges such as scalability, heterogeneity and technology innovation. This requires a transformation from the traditional centralised paradigm into a distributed one. In this article, a new distributed programming methodology, called Centralised Programming and Distributed Execution (CPDE), is proposed. CPDE relies on (i) the abstraction of the whole system as a distributed database; (ii) the use of the Smartlog declarative and reactive rule based language for expressing data manipulation; and (iii) the automatic Smartlog rule distribution according to data distribution. It thus provides a simple and straightforward mean for distributed programming. A centralised algorithm of fair over-voltage regulation of PV systems is used as a typical smart grids study case to validate the methodology and to compare it with centralized implementations. The experiments are implemented in a real-time simulation platform with a network of Raspberry Pis. In addition to showing its correctnes and ease of use, the performance of the CPDE implementation is studied, as well as its sensitivity to the increasing number of computing units and the data distribution. Results are promising and show the clear benefits of this methodology compared to more classical implementations.

In the control and management of smart grids, from steady state to real-time, the objective is to handle and to treat any change in the system as fast as possible, with as less resources as possible. In this context, this paper proposes a new language, called Smartlog, designed as declarative programming. Smartlog is developed for distributed computing in real-time and distributed database management. Compared to imperative programming, based on anticipation rather than reaction, the interest is to not ignore the meaning of some data, or to collect and analyze data without interest, and thus loose bandwidth and computational time. Smartlog is designed for operating smart grids, which are defined as abstract structures of large and scalable distributed databases. After its definition, the main features of the Smartlog language are its compactness, its simplicity and its scalability are shown. The language is tested on the application of a frequency and voltage secondary control of an islanded micro-grid in an experimental test-case, using a realtime simulator connected to Raspberry Pis. The characteristics of Smartlog are illustrated thanks to a comparison with an imperative programming implementation of the same regulation.