Real-time applications for electric power generation and control

The aim of an electric power control system is to supply electric energy to final users ensuring an adequate quality regardless to the constant changes in network topology, the variations in generation and the load fluctuations within the system itself. This dissertation deals with the control aspects of one of the main parameters involved in the quality of the service provided: the voltage value energy is supplied. It is herewith not intended to look at the definition of adequate quality of energy. Over the years several devices have been developed to control the voltage value in different parts of the power system. This work aims at studying in deep some of the aspects of the voltage control systems regulating the reactive power absorbed and injected into the network by generators. Voltage regulation in electrical systems is traditionally divided at primary level by operating on the reactive power of the single generator and by controlling the reactive power of entire power stations at secondary level. Ultimately these regulations are both carried out by varying the current or the excitation voltage in synchronous generators. This work presents a single hardware and software platform enabling the implementation of two digitally controlled devices: - a control system controlling the excitation in synchronous generators; - a system controlling the reactive power of the secondary voltage control in large power plants. This device is prescribed in the Italian network code since 2003 and is called SART (Automatic System for Voltage Regulation). These voltage regulators were historically born as analog devices and were subsequently implemented as digital controls using various technologies. The central topic of this dissertation is the implementation of the above-mentioned devices as digital control systems using microprocessors and general purpose computing systems, fitted out with operating systems for general use but with real-time characteristics. An emerging technique to quickly prototype a control system implies the utilization of high level simulation tools to design and simulate the plant to be controlled and automatically generate a control code. This work presents in detail the above-mentioned technique in the production and regulation of electric energy. The two control systems taken into consideration are designed and simulated using a high-level language and implemented with a modified Linux operating system (RTAI) in order to offer real-time performance. Furthermore, the experimental data of some SART device commissioning sessions are also included. In conclusion, the possibility of using the same platform for the development of similar voltage control devices to apply in the distribution network was investigated. The growth of little and medium-sized generation units, within the distribution network, which has taken place in the last decade, has introduced new issues in voltage regulation. For this reason a new control strategy was suggested for voltage controlling in distribution networks, where the generation is spread and control devices similar to the ones presented for the transmission network can be applied.