Large Amount Of Distributed Generation Research Articles

Optimal Voltage Control Using Inverters Interfaced With PV Systems Considering Forecast Error in a Distribution System

In recent years, distributed generation (DG) and renewable energy sources (RESs) have been attracting special attention in distribution systems. RESs such as photovoltaic (PV) systems are used as a source of green energy. However, a large amount of DGs causes voltage deviations beyond the statutory range in the distribution systems. This paper proposes a methodology for voltage control using the PV interfaced inverters and tap changing transformers. The proposed method uses a one-day schedule of voltage references for the control devices, which is determined by an optimization technique based on the forecast values of load demand and PV power generation. However, since the forecast value includes a forecast error, there is a possibility that the voltage control performance is affected. Thus, this paper introduces a replanning of the control reference schedule in order to reduce the forecast error impact on the control performance and its objectives.

Analysis of Voltage Profile Problems Due to the Penetration of Distributed Generation in Low-Voltage Secondary Distribution Networks

This paper presents a comprehensive analysis of the possible impacts of different penetration levels of distributed generation (DG) on voltage profiles in low-voltage secondary distribution networks. Detailed models of all system components are utilized in a study that performs hundreds of time-domain simulations of large networked distribution systems using the Electromagnetic Transients Program (EMTP). DGs are allocated in a probabilistic fashion to account for the uncertainties of future installations. The main contribution of this paper is the determination of the maximum amount of DG that secondary distribution networks can withstand without exhibiting undervoltage and overvoltage problems or unexpected load disconnections. This information is important for network planning engineers to facilitate the extension of the maximum penetration limit. The results show that depending on the location, type, and size of the installed DGs, small amounts of DG may cause overvoltage problems. However, large amounts of DG may not cause any voltage problems when properly selected.

A Novel Hybrid Network Architecture to Increase DG Insertion in Electrical Distribution Systems

Distribution networks will experience a deep mutation concerning their planning and operation rules due to the expected increase of distributed generation (DG) interconnection to the grid. Indeed, the opening of the electricity market or the growing global concern for environmental issues will lead to a massive development of DGs. Yet, a too large amount of DGs could raise technical problems on distribution networks which have not been planned to operate with bi-directional power flow. The existing solutions to solve marginal DG connections could be no longer relevant. The distribution network definitely has to evolve towards a smarter and more flexible network. Two possible ways to reach this goal are through new architectures and developing intelligent systems. This paper focuses on new architectures and operating modes. The traditional radial distribution network could accept more DGs by introducing appropriately specific loops. A new hybrid structure enabling the coexistence of the radial and meshed operation is proposed. It is equipped with autonomous circuit-breakers and automated switches that improve its reliability. A heuristic algorithm is also proposed to build this new architecture while ensuring the equality of consumers with respect to the continuity of service and while minimizing the global cost.

Effects of Distributed Generation on Voltage Levels in a Radial Distribution Network Without Communication

The challenges associated with incorporating a large amount of distributed generation (DG), including fuel cells, into a radial distribution feeder are examined using a dynamic MATLAB/SIMULINK™ model. Two generic distribution feeder models are used to investigate possible scenarios where voltage problems may occur. Modern inverter topologies make ancillary services, such as on-demand reactive power generation/consumption economical to include, which expands the design space across which DG can function in the distribution system. The simulation platform enables testing of the following local control goals: DG connected with unity power factor, DG and load connected with unity power factor, DG connected with local voltage regulation (LVR), and DG connected with real power curtailment. Both the LVR and curtailment strategies can regulate the voltage of the simple circuit case, but the circuit utilizing a substation with load drop compensation has no universal solution. Even DG with a penetration level around 10% of rated circuit power can cause overvoltage problems with load drop compensation. The real power curtailment control strategy creates the best overall circuit efficiency, while all other control strategies result in low light load efficiency at high DG penetrations. The lack of a universal solution implies that some degree of communication will be needed to reliably install a large amount of DG on a distribution circuit.