Microogrid with diesel generator ,wind turbine and solar farm with optimistic results using MATLAB SIMULATION
- 1. Abstract: A micro grid consists of group of loads and distributed generators that operate as a single controllable system. As an integrated energy delivery system microgrid can operate in parallel with or isolated from the main power grid. The microgrid concept introduces the reduction of multiple reverse conversions in an individual AC or DC sources and loads to power systems. The DGs has a local load connected to it which can be unbalanced or non-linear. Electrical utilities carefully monitor waveforms and currents at various network locations constantly, to understand what lead up to any unforeseen events such as power outage and blackouts by using power quality improvement algorithm. MATLAB/SIMULINK simulations are presented to express the proposed control system during various operating conditions, such as variation of wind, solar, diesel power generation and load, grid faults. INTRODUCTION- Many trends are becoming noticeable that will change the requirements of energy delivery. These modifications are being driven from both the demand and supply side where the integration of distributed generation and peak shaving technologies must be accommodated.Generally more than 90% of low voltage domestic customers are supplied by underground cable when the reset is supplied by overhead lines. The microgrid often supplies electricity through photovoltaic (PV) systems, wind turbines,Energy storage system etc. The energy storage systems usually include batteries. The storing device in the microgrid is equivalent to the rotating reserve of large generators in the conventional grid which ensures the balance between energy generation and consumption during rapid changes in load or generation. The development of microgrids can contribute to the reduction of emissions and the mitigation climate changes. This is due to the availability and developing technologies for distributed generation units are based on the renewable sources and micro sources that are characterized by very low emissions . Protection system is one of the major challenges for microgrid which must react to both main grid and microgrid faults. The protection system should cut off the microgrid from the main grid as rapidly as necessary to protect the microgrid loads for the first case and second case the protection system should isolate the smallest part of the microgrid when clears the faults. Microgrids have large power capacity and more control flexibility which accomplishes the reliability of the system as well as the requirement of power quality. microgrid is proposed which considers of generation and associated loads as a subsystem. This approach involves local control of distributed generation and hence reduces the need for central dispatch. The microgrid concept lowers the cost and improves the reliability of small
- 2. scale distributed generators. This concept permits high penetration of distribution generation without requiring redesign of the distribution system itself. The microgrid concept acts as solution to the problem of integrating large amount of micro generation without interrupting the utility networks operation. The microgrid or distribution network subsystem will create less trouble to the utility network than the conventional micro generation if there is proper and intelligent coordination of micro generation and loads. In case of disturbances on the main network, microgrid could potentially disconnect and continue to operate individually, which helps in improving power quality to the consumer. VARIABLE ENERGY SOURCES- In this paper two renewable and one conventional source is used. The renewable energy sources are wind and solar energy and the diesel energy is used as conventional energy sources. During the unavailable renewable sources diesel energy is used for utility. Solar Source-The solar source is used to generating power from the sun rays. A photovoltaic system makes use of some or more solar panels to convert the solar energy into electricity. It consists of various components which include the photovoltaic modules, mechanical and electrical connections and mountings and means of regulating and/or modifying the electrical output. The basic operation of PV cell is photoelectric effect. In this effect electrons ejected from the conduction band as a result of the absorption of sunlight. In a photovoltaic cell, when hits its surface, some portion of the solar energy is absorbed in the semiconductor material. The electrons moves from valance band into the conduction band when absorbed energy is greater than the band gap energy of the semiconductor. By these hole electron pairs are created in the illuminated region of the semiconductor. The electrons are creates in the conduction band are now free to move. These free electrons are enforced to move in a particular direction by the action of electric field present in the PV cells. The electrons flowing comprise current and can be drawn for external use by connecting a metal plate on the top and bottom of PV cell. This current and voltage produces required power. The photovoltaic system can generate direct current electricity without environmental impact when is exposed to sunlight.
- 3. Wind Source One of the renewable energy is used to generate the power and provide continuous supply to the utility. The wind varies with the majority reason is considerable seasonal changes of wind streams are observed. During the winter months wind speed usually greater than summer. Changes of wind speed are observed during a day, as a rule near to the seas the big lakes. During the morning the water is heats up than the earth faster. In the evening the earth cools down faster than water therefore a wind blows from coast. In practice the wind power is carried out by either wind turbine or by wind mill. The kinetic energy of a wind stream is transformed into mechanical energy is converted into electric energy of the generator. Normally the horizontal axis wind turbines are used. Nowadays the maximum capacity of practical wind turbines are about 2-4 MW. Wind turbines with low power are used for individual consumers and small economic objects. Wind turbines with unit power from 100 to 2000 kW are most extended for the power purposes. Diesel Generator The diesel generator is used to generate the power during unavailable renewable energy sources. And also this energy is used to provide continuous power supply to the consumers. In this paper diesel generator is used to generate the power during unavailable renewable energy sources. The packaged combination of a diesel engine, a generator and various ancillary devices such as base, canopy, sound attenuation, control systems, circuit breakers, jacket water heaters and starting system is referred to as a generating set. When running, the standby generator may be operated with a specified overload that can be tolerated for the expected short running time. For generating electrical power, it is essential to rotate the rotor of an alternator by means of a prime mover. The prime mover can be driven by different methods. Using diesel engine as prime mover is one of the popular methods of generating power. When prime mover of the alternator is diesel engine, the power station is called diesel power plant. The mechanical power required for driving alternator comes from combustion of diesel. As the diesel costs high, this type of power station is not suitable for producing power in large scale in our country. But for small scale production of electric power, and where there is no other easily available alternative of producing electric power, diesel power station is used.
- 4. Description – Objectives Demonstrate SimPowerSystems capabilities to simulate an electrical circuit and control system, in phasor mode, for a full-year period in less than one minute of simulation time. Illustrate concepts related to Energy Storage Systems (ESS). Show how to use public solar data time-series (TMY3 files) and how to create typical load profiles. Provide a tool to assist in determining appropriate ratings (power & capacity) for a generic ESS to be used on a distribution power system. Distribution Power System- It consists of a 120-kV transmission system equivalent supplying a 25-kV distribution substation. Several feeders are connected to the 25-kV bus of the substation. One of them supplies the power to a community that owns the PV farm, wind turbine, diesel generator and an energy storage system. The grounding transformer connected at the 25-kV bus provides a neutral point and limits the overvoltage on the healthy phases during a single-phase fault. Its zero-sequence impedance is three times the value of the grid positive sequence impedance. Dynamic Load Model- The Dynamic Load model implements a three-phase, three-wire dynamic load based on load profiles. The active power P and reactive power Q absorbed by the load vary as function of positive-sequence voltage V and load profiles data. P & Q vary as follows P=P_LoadProfile*(V/Vo)^np & Q=Q_LoadProfile*(V/Vo)^nq The profiles are daily load profiles specified on an hourly basis. They are stored in the LoadProfile_Datasets.mat file. For each load profile, the user specifies summer and winter data. Two sets of profiles are provided. The Build_LoadProfile_Datasets.m MATLAB script assist the user in creating additional load profiles. PV Farm and TMY3 Data -The TMY3 data block converts TMY3 solar irradiance data to Power. This power signal is fed to the PV Farm block that converts power signal to currents.
- 5. Energy Storage System (ESS) The Energy Storage System block contains the following components: - Control system - Unavailability monitor - Stored energy calculator - SPS Power-to-Current model and a 240/600V step-up Transformer. At any given time during the day, the control system determines the required power from the ESS in order to maintain the power below the specified value of the Maximum power allowed from the grid. This power signal is fed to a Power-to- Current block connected to a 240/600V step-up transformer. Although the power rating and capacity of the modeled ESS are respectively specified in kW and kWh as for a Battery Energy Storage System (BESS), this ESS could represent several types of storage systems, such as Flywheels, Compressed Air, Super Capacitors, Pumped Hydro, Superconducting Magnetic. Diesel Generator- Diesel Generator provides us Power about 15 MW. Wind turbine- Nominal Power 4.5Mw,Nominal wind speed – 13.5 m/s, Maximum wind speed -15 m/s. Load Profile -
- 6. Temperature and wind speed
- 7. SIMULINK MODELS – COMPLETE MICROGRID MODEL Inside pv
- 8. Inside diesel generator Inside residential load
- 9. Inside TMY-3 Energy Storage system
- 11. B 4 Output
- 12. Over all system output
- 13. Energy Error