PHYSCON 2011, Le ´ on, Spain, September, 5–September, 8 2011 POWER CONTROL OF VOLTAGE SOURCE CONVERTER FOR DISTRIBUTED GENERATION Jos´ e Luis Dom´ ınguez-Garc´ ıa Electrical Engineering Area IREC Spain jldominguez@irec.cat Oriol Gomis-Bellmunt CITCEA-UPC gomis@citcea.upc.edu and IREC ogomis@irec.cat Fernando Bianchi Electrical Engineering Area IREC Spain fbianchi@irec.cat Antoni Sudri ` a-Andreu CITCEA-UPC sudria@citcea.upc.edu and IREC asudria@irec.cat Abstract The paper deals with the active and reactive power control of voltage source converters (VSC) for dis- tributed generation. The control method explained is based on the instantaneous power theory. The power converter regulates the DC-Bus voltage and also con- trols the reactive power injected to the grid. The pre- sented control strategy is evaluated by simulation in Matlab-Simulink. Key words Distributed Generation, Converter control, PLL, Cur- rent loop, qd0 Transform 1 Introduction The rapid increment of renewable power generation is changing the power system shape, and creating new power generation concepts as distributed generation. Distributed generation can be defined, according to [Ackermann, Andersson and S¨ oder, 2001], as an elec- tric power source connected directly to the distribu- tion network or on the consumer side of the meter. On the other hand, CIGRE working group 37-23 de- fines it as low rating generation that is neither planned nor dispatched centrally and is usually connected to the distribution network [CIGRE working group 37-23, 1999]. Therefore, from the main ideas of both defini- tions, distributed generation can be understood as low power generation that is connected close to the distri- bution network. The power generation technologies in- volved in distributed generation include, for example, wind turbines, small hydro turbines, combined heat and power (CHP) units, also known as cogeneration, fuel cells and photovoltaics (PV) cells. In order to enhance the quality of the power injected to the grid by the units of distributed generation, a power converter is used between the grid and the generator en- abling the system to be regulated. Different control systems have been studied in order to provide different grid supports or ride through faults capability, e.g., frequency support [Hirodontis, Anaya- Lara, Burt and McDonald, 2009][Karlsson, Bj¨ ornstedt and Str¨ om, 2005], to guarantee power quality [Hornik and Zhong, 2009], voltage dips [Wang, Duarte and Hendrix, 2009], etc. The present paper studies and presents an active and reactive power control of a con- verter to enable the system to improve the quality of the power delivered. This paper is organized as follows. In Section II, the system under study is described. The Clarke and Park Transforms are presented in Section III. In section IV, the instantaneous power theory is briefly introduced. The control scheme is developed in section V. In sec- tion VI, the proposed control is validated by means of simulation and discussed. Finally, the conclusions are summarized in Section VII. 2 System description The system under study is shown in the Figure 1. It is a power converter transforming the active power deliv- ered by a dc-source, into the active and reactive power sent to the network. The dc-source can be either a pho- tovoltaic cell, a wind turbine connected to a rectifier or a fuel cell. To transform from DC to three-phase AC, it is neces- sary a three-phase inverter. The design of this power converter can be done by means of different technolo- gies as diode inverter, thyristor inverter or IGBT in- verter. Because of the ability to regulate active and re- active power, the IGBT inverters are commonly chosen to regulate the power delivery. 3 Transformation from abc reference frame to qd0 Current and voltage are usually described as three sinusoidal waves representing the three AC phases (a, b and c). Calculations in abc-frame are complex due