The solution is suitable for industrial zones or factories with frequent power outages, and the traditional way is that the user is equipped with a diesel generator as a backup power source, but the response speed of diesel engine startup is slow, which is easy to cause production line shutdown.
In order to improve the reliability of power supply, this scheme proposes to build a micro-grid for photovoltaic storage and diesel storage, and considers the subsequent expansion of micro-grid to be connected to small hydro-power or wind power.
Photovoltaic and energy storage are used as the main power supply in the operating state of the system, and the diesel engine is used as the emergency backup power supply, when the photovoltaic power generation is insufficient, at night, when the photovoltaic does not generate electricity on rainy days, and when the energy storage is out of power, it is used as the main power supply for the load to work, so as to provide the power supply reliability of the system.
At the same time, the expansion interface is reserved for later expansion in the micro-grid system.
The micro-grid system is composed of diesel power generation system , photovoltaic system, energy storage system, micro-grid controller, and micro-grid energy management system.
Overall design of the system
The project scheme uses photovoltaic system, energy storage system and diesel engine power generation system to supply power in a complementary way, complementing each other to ensure the stable, safe and reliable supply of power for the load. The overall configuration of the project is as follows:
1) Photovoltaic system: refers to all electrical equipment from solar cell modules to AC combiner box, including solar cell modules, photovoltaic inverters, AC combiner boxes, AC and DC cables, etc.;
2) Energy storage system: refers to all electrical equipment from the energy storage battery system to the energy storage bidirectional converter PCS, including bidirectional converter, battery rack, battery management system, energy storage energy management system, combiner cabinet, fire protection, temperature control, protection system, etc.;
3) Diesel generator system: the diesel generator that the user has built.
4) Micro-grid energy management system: including data acquisition device, server, software, etc.
5) Micro-grid controller: In order to realize the collaborative control of each source, grid, load and storage unit in the micro-grid, the project is equipped with a micro-grid controller. The photovoltaic energy storage power station outputs power according to the requirements of the dynamic balance of micro-grid power, and the grid-based energy storage power station provides dispatching power, frequency and voltage support, etc.
The photovoltaic and energy storage systems of the micro-grid system of this project adopt AC bus connection mode: the connection between the devices is clear, the power is decoupled from each other, it is easy to control, and the output characteristics are good.
The primary topology diagram and communication topology diagram of the micro-grid system are shown below.
Topology Diagram of Micro-grid System
Communication Topology Diagram of Micro-grid System
Products List：
No. | Item | Specification | Unit | Number | Remark |
1 | PV System | ...MWp | set | ||
1.1 | PV Panel | 580Wp/... | pcs | ||
1.2 | Inverter | 100kW/50kW | set | ||
2 | Containerized Energy Storage System | Rated capacity ...MW/...MWh (Include following Equipment per set) | set | ||
2.1 | Energy Storage Battery Compartment | Including temperature control system, fire protection system (combustible gas detection, perfluorohexanone fire extinguishing system), internal cables and accessories ,IP54 | set | Outdoor container | |
2.2 | Battery System | LFP cells, including battery clusters, switch boxes, BMS systems, battery racks, etc | set | ||
2.3 | Combiner Cabinet | DC combining | set | ||
2.4 | AC Control Panel | Auxiliary power supply | set | ||
2.5 | Energy Storage EMS | set | |||
2.6 | Net-Based PCS | Rated Power: 500kW(exclude isolation transformer) Rated Voltage: AC 400V | set | ||
3 | Micro-Grid Controller | Supporting micro-grid energy coordination control | set | ||
4 | Micro-Grid grid-connected cabinet | Connecting to the grid for PV, storage and DG | set | ||
5 | Micro-Grid EMS | set |
There are two operation modes: photovoltaic energy storage system as the main power supply, and diesel generator as the main power supply.
The operation mode of photovoltaic energy storage system as the main power supply needs to be configured with photovoltaic and energy storage capacity, which can meet the user's short-term peak load power supply, and the initial investment is larger, but the operation mode has less cost in the later stage, and the operation and maintenance are simple and convenient. Power generation does not require fuel, no pollution, no noise, and is more environmentally friendly. This mode of operation is suitable for customers who have a certain economic foundation and have a need for environmental protection and energy saving.
Diesel generators as the main power supply operation mode to configure photovoltaic and energy storage capacity is small. The initial investment is small, but the operation mode of diesel generator requires a large amount of diesel, and the later cost is larger, and the maintenance of diesel engine mechanical parts also requires a certain cost. Diesel generators generate a lot of exhaust gases and noise during power generation. This mode of operation is suitable for customers who plan to meet their basic power supply needs with less upfront investment.
Working mode: The energy storage system is used as the main power supply, and the diesel generator is used as the backup. The main power supply establishes a stable voltage in the micro-grid bus to ensure the power quality of the micro-grid, and the photovoltaic works in the MPPT mode for grid-connected power generation, and under the real-time monitoring of the micro-grid energy management system, the photovoltaic power generation, energy storage, and load operation are coordinated and work in the best mode, and the photovoltaic power generation system absorbs excess power when the load uses electricity, and the energy storage system releases electric energy when the photovoltaic power generation is less than the load electricity consumption, so as to ensure the maximum utilization of photovoltaic power generation.
Workflow: The grid-based energy storage bidirectional converter works in the voltage source mode, establishes a stable voltage on the bus, and the photovoltaic system is connected to the grid to provide sufficient power for the power load to ensure the normal power demand of the power load, and the excess power is stored in the energy storage battery through the energy storage bidirectional converter to store electric energy.
When the electric energy provided by the photovoltaic system and the energy storage system cannot meet the demand of the load, or the energy storage system is less, the backup diesel generator is connected, the diesel generator is used as the main power supply, and the stable voltage is provided for the micro-grid bus, and the diesel generator and the photovoltaic system provide electric energy for the load at the same time.
Operation Mode: Energy storage system is main power supply
The diesel generator is selected as the main power supply, and a stable voltage is established on the micro-grid bus to ensure the power quality of the micro-grid. Diesel generators, energy storage systems, and photovoltaic systems are all connected to the system. The energy storage system works in the grid-connected state, and the charging and discharging are dispatched, and when the electrical load is less, the output power of the diesel generator is less and the excess electric energy generated by the photovoltaic system is stored in the energy storage system; When the electrical load increases, the energy storage system will feed back the electrical energy in the battery to the 400V AC bus to provide sufficient electrical energy for the electrical load. In this working mode, the electric energy of the diesel generator and the photovoltaic system is coordinated through the monitoring system, so that the output power of the diesel generator is minimized, and the photovoltaic system works in the MPPT mode to ensure the maximum utilization of photovoltaic power generation.
Operation Mode: Diesel generator is main power supply
Diesel generators will produce a large amount of exhaust gases in the process of power generation, mainly including carbon dioxide, nitrogen oxides, etc. These exhaust gases pollute the environment, exacerbate global warming and air quality problems. At the same time, the diesel generator will produce large noise during operation, which will have a certain impact on the surrounding environment and personnel. The operation of diesel generators requires a large amount of fossil fuel, i.e., diesel. Due to the high price of fuel and the fluctuation of the market, the cost of electricity for diesel generators is also relatively high.
The photovoltaic power generation process does not consume fuel, does not emit any substances including greenhouse gases and other exhaust gases, does not pollute the air, and does not produce noise. It is a clean, non-polluting energy source that causes little damage to the environment. Photovoltaic systems have fewer mechanical moving parts and are easy to maintain. The service life of photovoltaic cell modules can usually reach more than 20 years, or even longer, although the initial investment in construction is relatively large, but the return on investment period of photovoltaic power generation system is relatively short.
Based on the above reasons, we proposes to adopt photovoltaic energy storage as the operation mode of the main power supply.
1) The photovoltaic and grid-based energy storage power station are the main power supply modes, which can realize the seamless switching between the system and the off-grid, and ensure the long-term uninterrupted power supply of the load after the mains power is cut off.
2) The unconsumed power generated by the photovoltaic system at the peak of sunshine intensity can be stored in the energy storage battery to increase the utilization rate of the power generated by the photovoltaic system.
3) When the solar irradiation intensity and load power change, the energy storage system can be started quickly to compensate for the output of the photovoltaic system and improve the stability and reliability of the system power supply.
4) As an emergency power supply, the diesel engine can supply power to the load when the photovoltaic does not generate electricity and the energy storage system is vented.
5) Micro-grid energy management system, comprehensive management and control of the system. It can realize the automatic switching of photovoltaic storage and diesel, and when the load is low, the diesel engine can be operated, and the power generated by the photovoltaic and diesel engine can be used directly for the load. The monitoring system coordinates the electrical energy of the diesel generator and the photovoltaic system, so that the output power of the diesel generator is minimized, so as to achieve the best economic benefits of the micro-grid.
Phone：+8613105230333
Whatsapp：+8613105230333
Email：13105230333@163.COM
Address：Wantong Plaza, No.99, Shiqu Street, Suzhou, China
