C I R E D 20 th International Conference on Electricity Distribution Prague, 8-11 June 2009 Paper 0374 CIRED2009 Session 4 Paper No 0374 LOCAL VOLTAGE CONTROL OF PVS IN DISTRIBUTION NETWORKS T. TRAN-QUOC T.M.C LE C. KIENY N. HADJSAID S. BACHA C. DUVAUCHELLE A. ALMEIDA IDEA IDEA IDEA IDEA G2Elab EDF Schneider Electric Tuan.Tran-Quoc@g2elab.inpg.fr ABSTRACT The connection of photovoltaic installations (PV) on a distribution network can cause important variations of voltage. Without regulation to maintain the voltage of the PV within the acceptable limits, that can cause a tripping of the PV. Thus this paper presents a development of a local voltage control based on auto-adaptive voltage control of PVs. This device by using local information permits to facilitate the connection of PVs and to reduce the cost of connection. This solution is able to control voltage not only at the connection point but also everywhere on the grid. The proposed solution is tested for a LV distribution network with presence of different types of PV with satisfied results. INTRODUCTION The energy production faces a big challenge for the future. World energy consumption increases approximately 2% per year. Nowadays, most of the worldwide production of energy is ensured by fossil sources. Energy thus will become a rarer good and expensive. The consumption of energy from the fossil sources faces to the exhaustion of these sources, the climate changes and the emission of C02. In this context, the European Union adopted the Directive on the promotion of the electricity produced from renewable energy sources on the electricity market. The objective of this directive is the promotion and the exploitation in the future potential of the renewable energy sources. Among the renewable energy sources, photovoltaic solar energy (PV) is a promising source. In the current economic context, very favorable to the development of PV (tariffs of purchase, tax credit, national or regional aids, etc), the number of requests for connection of PV is increasing in an exponential way, in particular for the applications in the sector of the building. The connection of photovoltaic installations (PV) on a distribution network (generally in LV network) induces, because of injection of active, a variation of the voltage profile and power flows on the network [1, 2]. The installation of this production can provide overvoltages on distribution network in case of light load and strong solar intensity. The changes of network operation (load and generation variation) and the intermittent productions of certain PV can cause important variations of voltage. Without regulation to maintain the voltage of the PV within the acceptable limits, that can cause a tripping of the PV. This paper presents a development of a local voltage control based on auto-adaptive voltage control of PVs. This device by using local information permits to facilitate the connection of PVs and to reduce the cost of connection. It permits to increase the rate of insertion, the performances and the flexibility of operation of PVs in an intelligent and adaptive way. This solution is able to control voltage not only at the connection point but also everywhere on the grid. A patent has been filed concerning this auto-adaptive regulator [5]. DEVELOPMENT OF AUTO-ADAPTIVE VOLTAGE CONTROL FOR PVS PV Inverters can be operated with different control schemes according to their operation mode [3, 4]. One of three types of reactive power compensation schemes can be applied for grid-tied inverters: either an active and reactive power control scheme (P/Q-control), or a control of active power and power factor (P/PF-control), or a control of active power and voltage (P/V-control). The voltage/frequency (V/f) control scheme is generally used for grid-forming inverters. For the P/Q control scheme, the active and reactive power outputs of PV are fixed to set-point values P ref and Q ref . Similarly, for the P/PF control scheme, the active power and the power factor are fixed to set-point values by changing the reactive power in order to maintain a constant power factor. For the V/f control scheme, the voltage and the frequency are fixed to set-point values V ref and f ref . The active and reactive powers are controlled in order to maintain a constant voltage and frequency. A ‘frequency-active power’- and ‘voltage-reactive power’-droop are used. The energy source is represented by a PV-power source. We can suppose that the dynamic of the entire system of the up-stream PV system(primary source) could be represented by a first-order response which enables to change the time constant according to the characteristics of the primary source. In addition to this dynamic part of the PV’s characteristics, the operation limits of active and reactive power are included. Only the described parameters, enhanced by primary energy availability, e.g. with variations of solar irradiation, define the characteristics of PV. The paragraph below describes the working principle of new local voltage control for PV: auto-adaptive voltage control.