Lucian Ioan Dulau

Automation of a distributed generation system

The paper describes the automatic generation control of a distributed generation (DG) system based on the optimal power flow. The optimization technique based on economical and technical considerations is presented. Also, an automation of the DG system is performed using a SCADA software considering the load, the availability of the systems generating units. Also, the optimal power dispatch is presented.

Distributed generation and virtual power plants

The paper describes the main characteristics of distributed generation (DG) and Virtual Power Plants (VPP). Distributed generation refers to the production of electricity near the consumption place using small-scale generating units. The distributed energy resources are renewable energies and cogeneration (simultaneous production of heat and electricity). A Virtual Power Plant is a cluster of DG installations (such as wind turbines, photovoltaic power plants, small hydro etc.) and any other sources of power that can cooperate together in the local area, and are controlled by a central control entity. The VPP is tested for different merit order values and grid connections (on-grid and off-grid) to track if this order is respected.

Economic analysis of a microgrid

A microgrid is a small-scale power grid that can be operated independently or in combination with the areas main electrical grid. Any small-scale localized station that has its own power resources, generation and loads and definable boundaries can be qualified as a microgrid. Microgrids can be intended as back-up power or to support the main power grid during periods of heavy demand. Microgrids involve multiple energy sources as a way of incorporating renewable power (such as wind turbines, photovoltaic panels, micro-hydro generators, biomass, fuel cells etc.). Microgrids can also reduce power costs, enhance reliability and reduce carbon emissions. In this paper an overview of the Microgrids concept is presented, examining the advantages and disadvantages of this system. A case study will be performed for a microgrid, considering power generation costs, generators output and loads demand. The microgrid comprises 6 distributed generators (DGs), 3 loads and a 150 kW storage unit. The installed capacity of the generators is 1100 kW, while the total load demand is 900 kW. The analysis will be performed for the entire day.

Impact of a photovoltaic power plant connection on the power system

This paper presents the situation of the photovoltaic power plants nationwide (Romania) and in particular the situation of the photovoltaic (PV) power plants in Mureş county. It also describes the minimal technical conditions that a PV power plant must fulfill before it is connected to the national grid. A particular case study consists of the impact that the PV power plant in Chirileu has on the Medium Voltage line Ungheni-Cipău and the interconnection High Voltage station in Ungheni. The case study contains an analysis of the voltage drops in predefined points, power flows with and without the PV power plant connected, respectively active power losses across the line. The study will be performed upon the photovoltaic power plant with an installed capacity of 3.2 MW connected to the 20 kV Ungheni-Cipău overhead power line and supplied from 220/110/20 kV Ungheni system station.

Optimization of a power system with distributed generation source

This paper describes the optimization of a power system that has connected a distributed generation source (a distributed generator). The optimal location of the distributed generator is determined first based on the power losses. Then, the optimization is performed for two objective functions, the generation cost and the power losses, subjected to constraints. The optimization is performed for two cases: when the distributed generator is connected to the system, and when the distributed generator is not connected to the system. The optimization results for the two cases are presented. The analyzes are performed with a specialized software for the simulation and analysis of power systems.

Applications of Virtual Power Plants approaches

The paper highlights the main characteristics of Virtual Power Plants (VPP). A Virtual Power Plant is a cluster of distributed generation units (such as photovoltaic power plants, wind turbines or small hydro) and any other sources of power that can cooperate together in the local area, and are controlled by a central control entity. An analysis of a VPP that is used to cover the load is performed for the whole day. The distributed generators from the VPP have different merit orders and outputs. Another analysis is performed for a power system in which a VPP is added. The analysis compares the power flow for the situations with and without the VPP.

Impact of photovoltaic power plants on power system losses

In this paper is presented the current situation of the photovoltaic power plants in Romania. Also, is analyzed the impact of two photovoltaic (PV) power plants, which are installed in the Mureş County, on a Medium Voltage Line. The PV power plants are connected to the Sovata-Fântânele 20 kV Overhead Medium Voltage line. The case study contains an analysis of the active and reactive power losses across the line with and without the PV power plants connected. The first PV power plant, installed in Sîngeorgiu de Pădure, has an installed power of 3.24 MW. The second PV power plant, installed in Ghindari, has an installed power of 1 MW.

Simulation of Smart Grid power dispatch

This paper presents the simulation of a smart grid power dispatch. Smart Grids can be defined as a modern power system that monitors, protects and automatically optimizes the operation of its interconnected elements (central and distributed generators, transmission and distribution network, industrial consumers, energy storage devices and end-use consumers). The simulation is performed for a system that is composed of four generators and one battery storage device considering the load power demand. The power dispatch is performed for the entire day. The dispatch is performed according to the ascending power production cost of the generating units.

Contributions to a grid connected distributed renewable energy System, in distinctive operation modes

This paper presents a design approach for renewable energy power systems operation in case of power outage or grid failure. The grid connected distributed power system delivers energy to the consumers located on the micro-grid, operating at distribution voltage level, and also delivering the remaining surplus energy to the main distribution grid. The optimal and permanent system operation is when the power grid is available and the distributed renewable energy system is feeding the generated energy to the power network. In case of power outage on the main power grid, the connected distributed power system shuts down, it is disconnected as a safety protocol. This is also elaborated as a standard and a safety measurement, presented in IEEE 1547 as a Standard for Interconnecting Distributed Resources with Electric Power Systems, developed by the Institute of Electrical and Electronics Engineers. The purpose is to define the distinctive operation modes of the grid connected distributed power system and to describe the operation management of the micro grid. The article presents a design approach for the grid connected distributed renewable solar power system and a hardware, software application on which these distinctive operation modes are observed. The application development for the proposed solution highlights the functional levels of the management system and emphasizes the role of supervisory control and data acquisition with a human machine interface.

Optimization of a power system with distributed generation sources

This paper describes the optimization of a power system with distributed generation (DG) sources. The optimization aims to minimize the electricity production costs ensuring that the load is served reliably and is conducted using the fmincon function in Matlab. The optimization is performed considering the power demand and the availability of the systems generating units, and equality restrictions. The optimization is performed first for steady-state condition, and second for the entire day. The optimization for the entire day is performed for two cases: when the DG sources are connected to the system and when the DG sources are not connected to the system. The test system comprises four generators and one load.