R. Campaner

New rules to employ distributed generators in voltage control: Assessment and numerical validation using DOME

In recent years, several countries have published new technical rules for the connection of distributed generators to medium and low voltage networks. A common requisite is that distributed generators should be able to module both active and reactive power. The paper duly reviews these rules and presents a variety of simulations referred to actual distribution networks using a new software tool: DOME.

Application of new voltage control rules in distribution networks

Several countries are undergoing a considerable development of distributed generation (DG). Hence, Distribution System Operators (DSO) are coping with unprecedented technical issues which force introducing new connection rules for customers that produce energy. This work focuses on voltage control issues of distribution systems with inclusion of distributed generation. A review of the standards that have been recently introduced is accompanied by a discussion on simulation results based on a real-world distribution grid. All simulations are solved with DOME, a novel Python-based software tool.

Evolution of the main economic parameters for photovoltaic plants installed in Italy

The Italian photovoltaic market is today the third worlds largest and represents a success story having attained the grid parity for certain type of residential and Commercial/Industrial (C&I) customers. In this paper, the main economic parameters involved in the installation of a photovoltaic plant (i.e. the Payback Time, the Internal Rate of Return and the Levelized Cost Of Energy) are calculated for three representative locations in Northern, Central, and Southern Italy. The parameters are calculated at different times between 2003 and 2014 considering different regime of governmental incentives and the grid parity scenario. The result of such analysis shows how the dramatic reduction of installation in the Italian market after 2011 cannot be directly related to a reduction of the economic convenience for the enduser. Moreover, the opportunities given by the attainment of the grid parity seem to have the potential to pave the way to a new impulse in the market of this solar technology.

Automatic voltage and reactive power control in distribution systems: Dynamic coupling analysis

The paper focuses on the dynamic response of a secondary voltage control scheme for distribution networks. The proposed control is based on a hierarchical architecture and is similar to the hierarchical voltage control implemented in some countries in high voltage transmission systems. The objective of the paper is to show a possible undesired dynamic coupling of different reactive power control loops of network generators. The effect of an algebraic decoupling matrix of the secondary voltage control as well as its effects simulated on a real-world case study are also duly discussed.

Automatic voltage control of a cluster of hydro power plants to operate as a virtual power plant

The paper proposes an application of a hierarchical automatic voltage regulation scheme for a cluster of hydro power plants connected to HV networks. The topology considered in the paper is a radial network in which the hydro power plants are connected to each other and have a single point of connection at the HV level. The technique proposed in the paper is based on well-assessed control strategies that are used in HV transmission systems, but has not been applied so far to medium voltage networks. A case study based on a cluster of hydro power plants composed of 11 generators and a distribution grid is presented and discussed in detail.

Coordinated voltage control of multi-converter power plants operating in transmission systems. The case of photovoltaics

Photovoltaic power plants connected to the high voltage transmission network are requested to support grid voltage regulation. This paper proposes a voltage and reactive power control for PV power plants based on a hierarchical voltage control which is typical in transmission systems but that has not been considered so far for distribution systems. The effectiveness of the proposed control scheme is duly discussed in the paper and tested through simulations.

Automatic voltage and reactive power regulator for wind farms participating to TSO voltage regulation

This paper proposes an application of a hierarchical automatic voltage regulation scheme for wind power plants connected to HV networks. The proposed control schemes is based on a given topology of wind power plants. In particular, we assume that wind generators are connected to each other and have a unique point of contact at the HV level. The secondary voltage control scheme proposed in the paper is based on well-assessed control strategies that are used in HV transmission systems, but has not been applied so far to medium voltage networks. A case study based on a wind power plant composed of 14 wind turbines and a distribution grid is presented and discussed in details.

Impact of Distributed Generation on power losses on an actual distribution network

Distributed Generation (DG) operating in a distribution network influences active power losses. In this paper power losses have been estimated for an actual low voltage distribution network and compared for different situations according to the DG penetration and placement of the power units. A practical method to place new DGs is presented. The basic idea is to minimize power losses, while complying voltage network limits, calculated with power flows using historical data over a discrete number of possible points of connection.

Automatic system for voltage control of large photovoltaic systems: Interactions with the transmission grid

In those electrical systems with an implemented secondary voltage regulation based on the reactive power of traditional fossil fuels power stations, it becomes more important that new renewable sources power plants participate to the voltage control. In this paper it is studied a voltage control for large photovoltaic systems. The control is applied to an actual large photovoltaic power plant. Simulations of the inside systems are shown together with the simulation of the plant inserted in the real high voltage transmission network. The interaction of this control with existing voltage controls of traditional power plants is detailed.

Electrical storage in distribution grids with renewable energy sources

Electric storage brings significant benefits to the electric systems by counteracting the strong constraint that the generated power has to be instantaneously balanced by load. This paper analyses the prospect of the introduction of a storage device into a small distribution grid considered as an energy hub.