Abstract: As the requirements for power supply reliability and power quality continue to increase, the demand for power generation using distributed energy systems is also increasing. This paper analyzes the distributed power system grid microgrid technology.
I. Grid Microgrid Overview The grid microgrid technology has emerged in recent years. The researchers of the study interpret the concept of the grid microgrid from different angles. The US ConsorTIumforElectricReliabilityTechnologySoluTIons (Power Reliability Solutions Association) believes that the grid microgrid is a small power system, which is in the public grid level, and is usually included in the distribution network. But it is also able to operate independently from the distribution grid to some extent. HatziargyriouND and DimeasA of the United States believe that the power grid ''> micro-grid power supply technology is a power supply system that uses primary energy to supply power and store energy. It is a power supply system that connects cold, heat and electricity. LasseterRH, PaigiP.Microgrid and LasseterRH also believe that the grid microgrid is an independent, controllable system consisting of a load and a micro-power supply. It can provide higher quality power and can be separated from the distribution network. Running.
Second, the overall energy system in the grid system The overall energy system of IES has a variety of uses, electrical equipment power supply, power drive, cooling, heating, and lighting and commercial, public buildings, indoor air delivery Wind, dehumidification, etc. In the IES system, if an IC (internal combustion engine), a gas turbine, or a fuel cell is used to generate electricity, an absorption chiller and a drying dehumidifier can be used, and a heat recovery device can be used to generate steam or hot water and recover. The residual heat is used for cooling, heating, and humidity control within the building, which significantly increases the efficiency of energy use, up to 85%. Compared with the traditional energy supply system, it can save more than 40%. Therefore, in the literature, this system will be defined as a system of cold, heat and electricity supply in buildings. There are three commonly used abbreviations: CHP (Cooling, HeaTingand PowerforBuildings), CCHP (CombinedCoolingHeaTIngandPower) and BCHP (BuildingsCooling, Heating and Power). ). In order to improve the reliability of the energy supplied by IES in the overall energy system, all subsystems are often operated side by side.
Third, the distributed energy system, the application of grid microgrid technology, the distributed power supply and access mode of the grid microgrid, due to the expansion of the power market in the world, the return period of the investment in power generation is long and several times in the international area Affected by the blackouts, the proportion of distributed power generation facilities among the newly added power sources is showing a strong upward trend. In 2000, the total number of new power sources in the world was 110 GW, of which distributed power generation accounted for about 3%. By 114 GW, which increased in 2004, the share of distributed generation facilities rose to around 7%. By the addition of 120 GW in 2008, the share of distributed generation facilities will reach 40%. Therefore, how to deal with the increasing development of distributed power generation is also an unavoidable problem. Contains distributed energy generator sets. As shown in the figure below, there are probably three modes of local power system LocalEPS1, 2, 3 interconnected with the regional power system AreaElectricPowerSystem (AreaEPS). The local power system 1 is a local power system in which the load is directly received by the PCC; the local power system 2 is a distributed power source juxtaposed with the AreaEPS through the PCC; the local power system 3 is a distributed power source and the load is juxtaposed with the AreaEPS through the PCC. When the regional power system AreaEPS is much stronger than the local power system LocalEPS, unlike the AreaEPS power generation, these distributed power generation devices, which can be regarded as virtual loads, are directly controlled by the user to start and stop, and do not participate in automatic power generation control, as long as they are installed on the distribution network side. Reverse power relay, it can not inject power into the grid when it is normal.
Regional Power System (AreaEPS); PointCommonCoupling (PCC) AreaEPS connection public connection point (connection point); PointofDRConnectionDR grid connection point; LocalEPS1 local power system 1 - local power system where load is directly received by PCC; LocalEPS2 local power system 2 - distribution The power supply is juxtaposed with AreaEPS through PCC; LocalEPS3 local power system 3—distributed power and load are juxtaposed with AreaEPS through PCC. For the local power system LocalEPS2, 3, as long as the distributed generator set starts, stops, and abnormalities and faults, the impact on the regional power system AreaEPS is obvious, and it is necessary to connect the interconnected system ICS of AreaEPS and DR.
The interconnected system of distributed power grid-connected technology of the grid micro-grid is a very important part of the grid's micro-grid. It is the part with the highest technical requirements, the most complicated design and the most varied, including step-by-step The power supply DR energy conversion device inverter and rectifier, induction synchronous generator; system control, electrical protection, steady state control and auxiliary equipment. The functions of ICS include: system start and stop and input and output control; and the system's steady voltage, current, reactive power and automatic adjustment of power to ensure the quantity and quality of power. When the system is abnormal or faulty, measures such as protection and safety control of system components should be taken.
Among the distributed power sources DG, internal combustion engines, gas turbines, cogeneration coal-fired units, and biomass power generation can all use conventional synchronous generators to achieve their energy conversion.
Among the many renewable energy technologies, wind power is the fastest growing area. The capacity of wind energy is between a few hundred W and a few MW. Usually, the asynchronous power generation technology we use is to convert wind energy into electrical energy. The technology of solar energy is the technology that has the greatest potential for renewable energy. The installed capacity of solar energy is between several W and several hundred KW. Usually, D/A switching technology is used to convert solar energy directly into electrical energy for use.
Conclusion Grid microgrid technology in distributed energy systems is one of the new technologies in the application of power systems in the contemporary world. It is one of the latest scientific and technological achievements applied by power systems. It is a modern energy conversion, power grid, power electronics. And the combination of technologies such as automatic control has been developed. The distributed energy system is characterized by its most optimized investment, the most effective use of energy, flexibility and loadability, and suitable renewable energy. It has become a centralized energy supply system. The missing and important supplement is an important direction for the development of energy technology in the future world.
I. Grid Microgrid Overview The grid microgrid technology has emerged in recent years. The researchers of the study interpret the concept of the grid microgrid from different angles. The US ConsorTIumforElectricReliabilityTechnologySoluTIons (Power Reliability Solutions Association) believes that the grid microgrid is a small power system, which is in the public grid level, and is usually included in the distribution network. But it is also able to operate independently from the distribution grid to some extent. HatziargyriouND and DimeasA of the United States believe that the power grid ''> micro-grid power supply technology is a power supply system that uses primary energy to supply power and store energy. It is a power supply system that connects cold, heat and electricity. LasseterRH, PaigiP.Microgrid and LasseterRH also believe that the grid microgrid is an independent, controllable system consisting of a load and a micro-power supply. It can provide higher quality power and can be separated from the distribution network. Running.
Second, the overall energy system in the grid system The overall energy system of IES has a variety of uses, electrical equipment power supply, power drive, cooling, heating, and lighting and commercial, public buildings, indoor air delivery Wind, dehumidification, etc. In the IES system, if an IC (internal combustion engine), a gas turbine, or a fuel cell is used to generate electricity, an absorption chiller and a drying dehumidifier can be used, and a heat recovery device can be used to generate steam or hot water and recover. The residual heat is used for cooling, heating, and humidity control within the building, which significantly increases the efficiency of energy use, up to 85%. Compared with the traditional energy supply system, it can save more than 40%. Therefore, in the literature, this system will be defined as a system of cold, heat and electricity supply in buildings. There are three commonly used abbreviations: CHP (Cooling, HeaTingand PowerforBuildings), CCHP (CombinedCoolingHeaTIngandPower) and BCHP (BuildingsCooling, Heating and Power). ). In order to improve the reliability of the energy supplied by IES in the overall energy system, all subsystems are often operated side by side.
Third, the distributed energy system, the application of grid microgrid technology, the distributed power supply and access mode of the grid microgrid, due to the expansion of the power market in the world, the return period of the investment in power generation is long and several times in the international area Affected by the blackouts, the proportion of distributed power generation facilities among the newly added power sources is showing a strong upward trend. In 2000, the total number of new power sources in the world was 110 GW, of which distributed power generation accounted for about 3%. By 114 GW, which increased in 2004, the share of distributed generation facilities rose to around 7%. By the addition of 120 GW in 2008, the share of distributed generation facilities will reach 40%. Therefore, how to deal with the increasing development of distributed power generation is also an unavoidable problem. Contains distributed energy generator sets. As shown in the figure below, there are probably three modes of local power system LocalEPS1, 2, 3 interconnected with the regional power system AreaElectricPowerSystem (AreaEPS). The local power system 1 is a local power system in which the load is directly received by the PCC; the local power system 2 is a distributed power source juxtaposed with the AreaEPS through the PCC; the local power system 3 is a distributed power source and the load is juxtaposed with the AreaEPS through the PCC. When the regional power system AreaEPS is much stronger than the local power system LocalEPS, unlike the AreaEPS power generation, these distributed power generation devices, which can be regarded as virtual loads, are directly controlled by the user to start and stop, and do not participate in automatic power generation control, as long as they are installed on the distribution network side. Reverse power relay, it can not inject power into the grid when it is normal.
Regional Power System (AreaEPS); PointCommonCoupling (PCC) AreaEPS connection public connection point (connection point); PointofDRConnectionDR grid connection point; LocalEPS1 local power system 1 - local power system where load is directly received by PCC; LocalEPS2 local power system 2 - distribution The power supply is juxtaposed with AreaEPS through PCC; LocalEPS3 local power system 3—distributed power and load are juxtaposed with AreaEPS through PCC. For the local power system LocalEPS2, 3, as long as the distributed generator set starts, stops, and abnormalities and faults, the impact on the regional power system AreaEPS is obvious, and it is necessary to connect the interconnected system ICS of AreaEPS and DR.
The interconnected system of distributed power grid-connected technology of the grid micro-grid is a very important part of the grid's micro-grid. It is the part with the highest technical requirements, the most complicated design and the most varied, including step-by-step The power supply DR energy conversion device inverter and rectifier, induction synchronous generator; system control, electrical protection, steady state control and auxiliary equipment. The functions of ICS include: system start and stop and input and output control; and the system's steady voltage, current, reactive power and automatic adjustment of power to ensure the quantity and quality of power. When the system is abnormal or faulty, measures such as protection and safety control of system components should be taken.
Among the distributed power sources DG, internal combustion engines, gas turbines, cogeneration coal-fired units, and biomass power generation can all use conventional synchronous generators to achieve their energy conversion.
Among the many renewable energy technologies, wind power is the fastest growing area. The capacity of wind energy is between a few hundred W and a few MW. Usually, the asynchronous power generation technology we use is to convert wind energy into electrical energy. The technology of solar energy is the technology that has the greatest potential for renewable energy. The installed capacity of solar energy is between several W and several hundred KW. Usually, D/A switching technology is used to convert solar energy directly into electrical energy for use.
Conclusion Grid microgrid technology in distributed energy systems is one of the new technologies in the application of power systems in the contemporary world. It is one of the latest scientific and technological achievements applied by power systems. It is a modern energy conversion, power grid, power electronics. And the combination of technologies such as automatic control has been developed. The distributed energy system is characterized by its most optimized investment, the most effective use of energy, flexibility and loadability, and suitable renewable energy. It has become a centralized energy supply system. The missing and important supplement is an important direction for the development of energy technology in the future world.
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