With the gradual exhaustion of conventional energy sources and environmental pollution is increasing , countries around the world have started to pay attention to wind power, photovoltaic power generation as the representative of environmentally friendly, efficient and flexible way of generating electricity - distributed generation . The micro-grid distributed generation units in the form of access to a large network and network operation, with large grid supporting each other , is to play the best way to distributed generation performance .
Distributed generation and smart micro- grid system is defined by the distributed generation units , energy storage subsystem , related to load , energy management systems, and monitoring and protection devices made of a small collection of hair distribution system , is a self-control can be achieved , protection and management of the autonomous system, which can be incorporated into both the joint operation of large power grids can also be run independently isolated network . The flexible operating mode greatly improves efficiency of distributed power generation unit , and improve the reliability of power supply load . After the internal micro-grid energy management , the single-point and multi- network distributed generation units can be reduced on the impact of large power grids . Meanwhile , the dispersion microgrid different types of distributed power generation unit combined unified management , can fully compensate for the lack of the power generation unit , so that each of the distributed power generation unit for higher efficiency. Thus, the future of the power distribution network is bound to contain a large number of micro- grid system , its key technologies of distributed generation units will be the key to large-scale application .
Through micro-grid control systems , energy storage systems, coordination and balance a variety of distributed generation units , the conventional run-time run with the big power grid , power generation, electricity surplus will enter into a large grid or energy storage systems, power generation from large power shortage purchase electricity or network storage subsystems using micro- power . Once the micro-grid detect large power grid or fails, the rapid and large grid splitting into isolated operation , in order to protect the load continuous and reliable power supply .
Micro-grid and grid active and reactive power regulation function
Microgrid receiving grid scheduling instructions to achieve a variety of functions , including: the active power delivered to the grid needs to provide the required grid reactive power , to achieve low voltage ride , improve grid stability.
Micro-grid and grid load shifting , load leveling , peak FM function
Micro-grid energy storage subsystem using the surplus energy is stored in the power grid , the grid power is low maximum power output of distributed generation and energy storage subsystem unit of energy .
Microgrid isolated network storage subsystem under voltage, frequency adjustment function
Isolated Network storage subsystem under voltage frequency scaling features to meet the needs of different loads .
Isolated microgrid under the net " black start " function
In the case of power grid , micro-grid energy storage subsystem can take advantage of established voltage, frequency support , making access to distributed generation units and load voltage reference resume operation.
Micro power grid network switch isolated when active, passive isolated network functions
Power outage planned in the case of micro-grid monitoring and protection subsystem can occur isolated network signal active , the storage subsystem proactive response is isolated network seamless switching function ; also provides passive micro-grid isolated network functions, namely non- grid planned power outage in the case , the storage subsystem identification directly after disconnecting power grid and micro-grid network switch , and in the establishment of micro- network voltage and frequency support, to achieve passive solitary network functions.
Microgrid isolated network switch and network time synchronization function
Micro-grid and network operation to be transferred , by the monitoring protection directive issued earlier , the storage subsystem within the network by adjusting the voltage and frequency micro- grid voltage and frequency to achieve co-ordination , to meet the requirements of seamless closing .
Micro-grid distributed generation units
With wind power, photovoltaic power generation, diesel gas turbines and other distributed generation units ;
Perfect protection function to prevent damage to the converter equipment ;
LVRT , islanding detection and other protection features to meet grid access standards ;
Low harmonic content and output stabilization , reducing the impact on the grid power quality ;
Rich communication interfaces to meet RS485, CAN, Ethernet communication interface .
Micro- grid energy storage subsystem
With multiple types of battery energy storage, super capacitors, flywheel energy storage body choice ;
The storage subsystem higher conversion efficiency of 97%, reducing the energy loss storage subsystem ;
VF runtime with isolated network regulator FM function ;
For the micro power grid provide reactive support and power factor correction ;
Dynamic tracking grid voltage for the micro-grid to provide seamless switching voltage reference ;
Friendly interface , real-time display storage converter , energy storage body and other operating parameters .
Microgrid Energy Management Subsystem
With micro- network energy self-balancing , distributed power optimal control, micro- economic network optimization and other energy management strategies for the user to switch freely according to the actual situation ;
Distributed generation output unit outputs statistics and forecasting capabilities ;
Load user-side energy management and optimization of power control ;
For the grid to provide " load shifting ", " frequency control " and other advanced features application interface .
Micro-grid monitoring and protection subsystem
With accurate and reliable current protection, voltage protection, distance protection , differential protection and other protection ;
Bidirectional energy flow differential protection function , more suitable for micro-grid application requirements ;
Protection devices to meet the needs of the active micro-grid isolated network , passive isolated network , such as converting a logical demand over the same period ;
PCC microgrid fast switch , micro- grid and large power grid to achieve the rapid isolation ;
With rich communication interface, acceptable dispatching dispatch center .