CN105470997A - Microgrid control system - Google Patents

Abstract

The present invention provides a microgrid control system, including: an energy management system, a detection system, and a microgrid system. The microgrid system includes: a photovoltaic power generation unit, a wind power generation unit, an energy storage unit, and an important load. The detection system is used to detect energy storage The remaining power SOC of the unit, the operating active power P _PV (t) of the photovoltaic grid-connected inverter of the photovoltaic power generation unit, the operating active power P _WP (t) of the wind turbine grid-connected inverter of the wind power generation unit, and the active power P _l1 of important loads (t), also includes the micro-turbine power generation unit. When the micro-grid system is running in isolation, if the output of the photovoltaic power generation unit and the wind power generation unit is insufficient, the micro-gas turbine power generation unit can be started to provide power supply for the load, which can reduce The energy storage capacity of the battery of the energy storage unit can reduce environmental pollution, reduce the cost of microgrid construction and operation and maintenance, and improve the reliability of microgrid isolated grid operation.

Description

A microgrid control system

technical field

The invention relates to the technical field of micro-grid operation control, in particular to a micro-grid control system.

Background technique

Photovoltaic power generation, wind power generation and other renewable energy power generation technologies have been widely concerned and applied. In some small towns, pastoral areas, islands and other areas that have useful electricity demand but are not convenient for large-scale power grid construction, the application of renewable energy can reduce the construction cost. It is of great significance to achieve energy saving and emission reduction. In order to make full use of renewable energy, micro-grid technology is used to connect distributed energy and loads, which not only realizes the local utilization of renewable energy, reduces losses, but also realizes the reasonable dispatch of electric energy in the region and improves the reliability of power consumption. . Microgrid, also known as microgrid, is a system composed of a group of distributed power sources, loads, energy storage systems and control devices. Microgrid is an autonomous system that can realize self-control, protection and management, and can be connected to the external power grid. , can also be run in isolation.

When the microgrid operates in an isolated grid, due to the lack of capacity support provided by the large grid, the first task is to establish a stable and reliable voltage and frequency reference. Since renewable energy sources such as photovoltaic and wind energy and loads in microgrids are fluctuating and uncertain, energy fluctuations need to be balanced. At present, large-capacity energy storage units are usually used to realize this function. When the power generation of renewable energy is greater than the demand of the load, the electric energy is stored; Discharge to supplement the electricity required by the load.

At present, commonly used energy storage units are usually realized by chemical energy storage batteries (ie storage batteries), such as lead-acid batteries, lithium-ion batteries, iron batteries, etc. high maintenance cost and poor security. At present, when the microgrid is running in isolation, in order to reduce the impact of renewable energy and load mutations on the grid, and ensure the power supply when renewable energy is insufficient, it is often necessary to increase the energy storage capacity of the battery, which makes the microgrid construction And operation and maintenance costs increase, correspondingly, batteries with larger energy storage capacity will also have more serious impact on the ecological environment.

Therefore, there is an urgent need for a microgrid control scheme to solve the above technical problems.

Contents of the invention

Aiming at the above-mentioned deficiencies in the prior art, the present invention provides a micro-grid control system to solve the problems of high construction and operation and maintenance costs of the micro-grid and great impact on the ecological environment when the micro-grid operates in an isolated network.

In order to solve the problems of the technologies described above, the present invention adopts the following technical solutions:

The present invention provides a microgrid control system, including: an energy management system, a detection system, and a microgrid system. The microgrid system includes: a photovoltaic power generation unit, a wind power generation unit, an energy storage unit, and an important load. The detection system is used to detect energy storage The remaining power SOC of the unit, the operating active power P _PV (t) of the photovoltaic grid-connected inverter of the photovoltaic power generation unit, the operating active power P _WP (t) of the wind turbine grid-connected inverter of the wind power generation unit, and the active power P _l1 of important loads (t), the micro-grid system also includes a micro-turbine power generation unit;

The energy management system is used to receive the SOC detection value, P _l1 (t), PP _PV (t) and P _WP (t) sent by the detection system when the microgrid system is running in isolation, and compare the SOC detection value with the preset SOC upper limit SOC _max is compared with SOC lower limit SOC _min , and the sum of PP _PV (t) and P _WP (t) is calculated; and, according to the comparison result, the sum of PP _PV (t) and P _WP (t) and P _l1 (t), control the micro-turbine power generation unit to start, or, according to the comparison result, the sum of PP _PV (t) and P _WP (t), P _l1 (t) and the preset PCS rated active power P of the energy storage unit _LSmax , to control the micro-turbine power generation unit to start.

Further, the microgrid system also includes general controllable loads;

The energy management system is specifically used to, when it is judged that the SOC detection value is less than or equal to SOC _min , cut off the general controllable load, calculate the sum of PP _PV (t) and P _WP (t), and calculate the PP _PV ( The sum of t) and P _WP (t) is compared with P _l1 (t), if the sum of PP _PV (t) and P _WP (t) is less than P _l1 (t), the micro-turbine power generation unit is controlled to start ; When it is judged that the SOC detection value is greater than SOC _min and less than SOC _max , calculate the sum of PP _PV (t) and P _WP (t), and combine the sum of PP _PV (t) and P _WP (t) with P _l1 (t) comparison, if the sum of the P _PV (t) and P _WP (t) is less than P _l1 (t), then calculate the difference between P _l1 (t) and P _LSmax , and the P _PV (t ) and P _WP (t) and the difference between P _l1 (t) and P _LSmax , if the sum of P _PV (t) and P _WP (t) is less than the P _l1 (t) and The difference between P _{and LSmax} controls the start-up of the micro-turbine power generation unit.

Further, the microgrid system also includes general controllable loads;

The energy management system is also used to control the shutdown of the micro-turbine power generation unit according to the comparison result, or, according to the comparison result, the sum of P _PV (t) and P _WP (t), P _l1 (t) and The preset rated active power P _l2max of the general controllable load controls the shutdown of the micro-turbine power generation unit.

Preferably, the energy management system is specifically used to, when it is judged that the SOC detection value is greater than or equal to SOC _max , control the power generation unit of the micro-combustion engine to close, calculate the sum of P _PV (t) and P _WP (t), and The sum of PP _PV (t) and P _WP (t) is compared with P _l1 (t), if the sum of PP _PV (t) and P _WP (t) is greater than or equal to P _l1 (t), then The control part generally controls the load input into the microgrid system; when it is judged that the SOC detection value is greater than SOC _min and less than SOC _max , and the sum of the P _PV (t) and P _WP (t) is greater than or equal to P _l1 (t ), calculate the sum of P _l1 (t) and P _l2max , and compare the sum of P _PV (t) and P _WP (t) with the sum of P _l1 (t) and P _l2max , if the If the sum of P _PV (t) and P _WP (t) is less than the sum of P _l1 (t) and P _l2max , the micro-turbine power generation unit is controlled to be closed, and some general controllable loads are controlled to be put into the micro-grid system .

Further, the energy management _system is further _{configured to} calculate _{P l1} (t ), the sum of P _l2max and P _LSmax , and comparing said sum of P _PV (t) and P _WP (t) with said calculated sum of P _l1 (t), P _l2max and P _LSmax , if said If the sum of P _PV (t) and P _WP (t) is less than the sum of P _l1 (t), P _l2max and P _LSmax , all general controllable loads are controlled to be input into the microgrid system.

Further, the energy management system is also used to reduce wind power if the sum of P _PV (t) and P _WP (t) is greater than or equal to the sum of P _l1 (t), P _l2max and P _LSmax The wind turbine grid-connected inverter of the power generation unit operates with active power P _WP (t).

Further, the detection system is also used to detect the active power P _PCC (t) of the common connection point PCC point and the active power P _DG (t );

The energy management system is also used to receive the P _PCC (t) and _PDG (t) sent by the detection system when the microgrid system is connected to the grid, and according to the P _PCC (t), _PDG (t) and preset The PCC point active power upper limit P _PCCmax is set to control the shutdown of the micro-turbine power generation unit.

Preferably, the energy management system is specifically used to compare P _PCC (t) with P _PCCmax , and when P _PCC (t) is greater than or equal to P _PCCmax , determine whether P _DG (t) is greater than 0, if P _DG (t) is greater than 0, then control the micro-turbine power generation unit to shut down.

Further, the detection system is also used to detect the grid-connected power Pb(t) of the energy storage unit;

The energy management system is also used to compare P _PCC (t) with P _PCCmax after controlling the shutdown of the micro-turbine power generation unit, and if P _PCC (t) is greater than or equal to P _PCCmax , then adjust the grid connection of the energy storage unit Power Pb(t), and compare Pb(t) with the rated power of the energy storage unit -P _Cnet (t) in the set state of charge, if Pb(t) is less than -P _Cnet (t), then control the energy storage The unit operates at rated power, and the grid-connected power P _V (t) of the photovoltaic power generation unit is reduced to 0, and P _PCC (t) is compared with P _PCCmax . If P _PCC (t) is greater than or equal to P _PCCmax , the wind power The grid-connected power P _W (t) of the generating unit is reduced to 0.

Further, the detection system is also used to detect the grid-connected power Pb(t) of the energy storage unit and the grid-connected power P _W (t) of the wind power generation unit;

The energy management system is also used to receive the P _PCC (t), P _W (t) and Pb (t) sent by the detection system when the microgrid system is connected to the grid, and according to the P _PCC (t), P _W (t), Pb(t), the preset lower limit of the active power of the PCC point P _PCCmin and the set rated power of the energy storage unit P _Cnet (t) in the discharge state to control the start-up of the micro-turbine power generation unit.

Preferably, the energy management system is specifically used for, when P _PCC (t) is less than or equal to P _PCCmin , if it is judged that P _W (t) is 0, then control the start of the wind power generation unit, and judge whether the wind power generation unit is in MPPT mode, if yes, compare P _PCC (t) with P _PCCmin , if P _PCC ( _t ) is less than or equal to P _PCCmin , then judge whether the grid-connected power PV (t) of the photovoltaic power generation unit is 0, if so, then Start the photovoltaic power generation unit and judge whether the photovoltaic power generation unit is in MPPT mode, if so, compare P _PCC (t) with P _PCCmin , if P _PCC (t) is less than or equal to P _PCCmin , then adjust the grid-connected power of the energy storage unit Pb(t), and compare Pb(t) with the rated power P _Cnet (t) of the energy storage unit in the discharge state, if Pb(t) is greater than P _Cnet (t), then control the energy storage unit with P _Cnet (t) runs and controls the micro-turbine power generation unit to start.

In the present invention, a micro-gas turbine power generation unit is set in the micro-grid system. When the micro-grid system operates in an isolated network, if the output of the photovoltaic power generation unit and the wind power generation unit is insufficient, the micro-gas turbine power generation unit can be started to provide power supply for the load. Reduce the energy storage capacity of the battery of the energy storage unit, thereby reducing environmental pollution, reducing the construction and operation and maintenance costs of the microgrid, and improving the reliability of the isolated grid operation of the microgrid.

Description of drawings

FIG. 1 is a system structure diagram of a microgrid control system provided by an embodiment of the present invention;

FIG. 2 is a schematic diagram of a microgrid isolated network operation control process 1 provided by an embodiment of the present invention;

FIG. 3 is a schematic diagram of a microgrid isolated network operation control process 2 provided by an embodiment of the present invention;

FIG. 4 is a schematic diagram of a microgrid isolated network operation control process 3 provided by an embodiment of the present invention;

FIG. 5 is a schematic diagram of a microgrid grid-connected operation control process 4 provided by an embodiment of the present invention;

FIG. 6 is a schematic diagram of a microgrid grid-connected operation control process 5 provided by an embodiment of the present invention.

detailed description

The technical solutions in the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the present invention. Apparently, the described embodiments are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The present invention coordinates the relationship between the energy storage unit and the micro-gas turbine power generation unit by setting the micro-turbine power generation unit in the micro-grid system, that is, according to the active power of the photovoltaic power generation unit, the wind power generation unit and the load, and the energy storage unit According to the change of the remaining power, the operating state and output power of the micro-turbine power generation unit are controlled to reduce the energy storage capacity of the energy storage unit.

Fig. 1 is a schematic diagram of the system architecture of the microgrid control system provided by the embodiment of the present invention. As shown in Fig. 1, the microgrid control system includes: an energy management system 1, a detection system 2 and a microgrid system 3, and the microgrid system 3 includes : Photovoltaic power generation unit 31, wind power generation unit 32, energy storage unit 33 and important load 34, the detection system 2 is used to detect the remaining power SOC of the energy storage unit 33, the photovoltaic grid-connected inverter operating active power P of the photovoltaic power generation unit 31 _PV (t), wind turbine grid-connected inverter of wind power generation unit 32 operates active power P _WP (t) and important load active power P _l1 (t). Preferably, the microgrid system 3 may also include a general controllable load 36, and correspondingly, the detection system 2 is also used to detect the active power P _l2 (t) of the general controllable load.

The micro-grid control system of the present invention is an AC busbar system. Power sources such as photovoltaic power generation unit 31, wind power generation unit 32, energy storage unit 33, and micro-turbine power generation unit 35 are connected to the same 380V AC busbar, and important loads 34 and general The load control 36 is also connected to the same 380V AC bus, and the microgrid system 3 can be connected to the large power grid through a grid-connected cabinet (not shown in the figure).

Due to the characteristics of fast start-up, low noise and good controllability, the micro-gas turbine can be used as a reliable backup power source in areas with sufficient natural gas supply. That is to say, the photovoltaic power generation unit 31, the wind power generation unit 32, the energy storage unit 33 and the micro-turbine power generation unit 35 can all be used as power sources of the microgrid system 3 to supply power for important loads and/or general controllable loads. Among them, the energy storage unit 33 can quickly output or absorb power to keep the micro grid system stable when the power fluctuation of the micro grid system 3 is large, and the micro gas turbine power generation unit 35 can be used when the output of the photovoltaic power generation unit 31 and the wind power generation unit 32 is insufficient. Provide long-term power support.

The microgrid system 3 can operate in an isolated grid, or it can be connected to the large grid. The microgrid system 3 uses the energy storage bidirectional converter PCS to realize seamless switching from grid to grid, and to stabilize fluctuations in power supply or load mutations .

The following parameters can be preset in the energy management system 1:

1. The upper limit of the remaining power of the energy storage unit SOC _max and the lower limit of the remaining power of the energy storage unit SOC _min ;

2. PCS rated active power P _LSmax of the energy storage unit;

3. Rated active power P _l2max of general controllable loads;

4. PCC point active power upper limit P _PCCmax and PCC point active power lower limit P _PCCmin .

The following describes the control process of the microgrid control system when the microgrid is in isolated grid operation and grid-connected operation.

When the microgrid is running in isolation, the grid-connected switch K9 is turned off, and the photovoltaic power generation unit 31 and the wind power generation unit 32 in the microgrid system 3 both generate electricity in the maximum power operation mode. The power deficit of the microgrid system is balanced by the PCS, and the In standby power state.

After the energy management system 1 receives the SOC detection value sent by the detection system 2, it compares the SOC detection value with SOC _min and SOC _max respectively, and if the SOC detection value is less than or equal to SOC _min , then executes control process 1 (control process 1 is in Detailed description later), if the SOC detection value is greater than SOC _min and less than SOC _max , then execute control process 2 (control process 2 will be described in detail later), if the SOC detection value is greater than or equal to SOC _max , execute control process 3 (control Process 3 will be described in detail later).

When the microgrid system 3 is running in isolation, the energy management system 1 can receive the SOC detection value, P _l1 (t), _PPV (t) and P _WP (t) sent by the detection system 2, and compare the SOC detection value with the preset The SOC upper limit SOC _max is compared with the SOC lower limit SOC _min , and the sum of PP _PV (t) and P _WP (t) is calculated; and, according to the comparison result, the sum of PP _PV (t) and P _WP (t) and P _l1 (t), control the micro-turbine generating unit 35 to start.

The control flow 1 will be described in detail below with reference to FIG. 2 and FIG. 1 . As shown in Figure 2, during the operation of the isolated microgrid, when the energy management system 1 determines that the SOC detection value is less than or equal to the SOC _min , the control process 1 is executed, and the control process 1 includes the following steps:

Step 201, cut off the general controllable load.

Specifically, when the energy management system 1 judges that the SOC detection value is less than or equal to the SOC _min , it means that the remaining power of the energy storage unit 33 is too low at this time. In order to ensure the normal operation of the important load 34, the energy management system 1 generally can The load 36 is controlled so that the energy storage unit 33 no longer supplies power to the general controllable load 36.

Step 202, calculate the sum of _PPV (t) and _PWP (t).

Specifically, the energy management system 1 transmits the active power P _PV (t) of the photovoltaic grid-connected inverter of the photovoltaic power generation unit and the active power P _WP (t) of the wind turbine grid-connected inverter of the wind power generation unit sent by the detection system 2. , calculate the sum of P _PV (t) and P _WP (t).

Step 203, compare the sum of PP _PV (t) and P _WP (t) with P _l1 (t), if the sum of PP _PV (t) and P _WP (t) is less than P _l1 (t), then Execute step 204, otherwise, keep the current states of the power sources and loads unchanged.

Specifically, if the energy management system 1 determines that the sum of P _PV (t) and P _WP (t) is less than P _l1 (t), it means that the sum of the output powers of the photovoltaic power generation unit 31 and the wind power generation unit 32 cannot satisfy For important loads, the energy storage unit 33 is in a discharge state, so other power sources are needed to provide power, and the micro-turbine power generation unit is started (that is, step 204 is executed).

If the energy management system 1 determines that the sum of _{PPV (t) and PWP (t) is greater than P l1 ( t} ), it means that the energy storage unit 33 is in the charging state at this time, and the energy management system 1 maintains the current power generation unit and wind power generation unit) and loads (that is, important load 34 and general controllable load 36 ) are unchanged, so that the energy storage unit 33 is charged and operated.

Step 204, controlling the start-up of the micro-turbine power generation unit.

Specifically, the energy management system 1 controls the start-up of the micro-gas turbine, thereby starting the power generation unit 35 of the micro-gas turbine for grid-connected operation.

When the microgrid system 3 is running in isolation, the energy management system 1 can receive the SOC detection value, P _l1 (t), _PPV (t) and P _WP (t) sent by the detection system 2, and compare the SOC detection value with the preset Compare the SOC upper limit SOC _max with the SOC lower limit SOC _min , and calculate the sum of PP _PV (t) and P _WP (t), according to the comparison results, the sum of PP _PV (t) and P _WP (t), P _l1 ( t) and the preset PCS rated active power P _LSmax of the energy storage unit to control the start-up of the micro-turbine power generation unit 35 . And, according to the comparison result, the sum of P _PV (t) and P _WP (t), P _l1 (t) and the preset general controllable load rated active power P _l2max , the micro-turbine power generation unit 35 is controlled to shut down.

The control flow 2 will be described in detail below in conjunction with FIG. 3 and FIG. 1 . As shown in Figure 3, during the operation of the isolated microgrid, when the energy management system 1 judges that the SOC detection value is greater than the SOC _min and less than the SOC _max , the control process 2 is executed, and the control process 2 includes the following steps:

Step 301, calculate the sum of _PPV (t) and _PWP (t).

Step 302, compare the sum of PP _PV (t) and P _WP (t) with P _l1 (t), if the sum of PP _PV (t) and P _WP (t) is less than P _l1 (t), then Execute step 303, otherwise, execute step 306.

Specifically, if the energy management system 1 determines that the sum of P _PV (t) and P _WP (t) is less than P _l1 (t), it means that the output power of the photovoltaic power generation unit 31 and the output power of the wind power generation unit 32 are summed at this time. If the demand of the important load 34 cannot be met, the energy storage unit 33 discharges to realize the power balance of the microgrid system, and the energy management system 1 further judges whether the energy storage unit 33 can meet the demand of the important load 34 when discharging at full power (i.e., execute Step 303).

If the energy management system 1 determines that the sum of P _PV (t) and P _WP (t) is greater than or equal to P _l1 (t), it means that the sum of the output power of the photovoltaic power generation unit 31 and the output power of the wind power generation unit 32 can be If the requirement of the important load 34 is met, it can be further judged whether the requirement of the important load 34 and the requirement of the general controllable load 36 are met, that is, step 307 and subsequent steps are executed.

Step 303, calculate the difference between P _l1 (t) and P _LSmax .

Step 304, comparing the sum of P _PV (t) and P _WP (t) with the difference between P _l1 (t) and P _LSmax , if the sum of P _PV (t) and P _WP (t) is less than For the difference between P _l1 (t) and P _LSmax , execute step 305; otherwise, keep the current states of the power sources and loads unchanged.

Specifically, if the energy management system 1 determines that the sum of _{PPV (t) and PWP (t) is less than the difference between P l1 (t) and P LSmax , it} means that the energy storage unit 33 is discharging at full power at this time. It is also unable to meet the demand of the important load 34, therefore, in order to realize the power balance of the microgrid system 3, it is necessary to start the micro-turbine power generation unit 35 (that is, execute step 305).

If the energy management system 1 judges that the sum of _PPV (t) and P _WP (t) is greater than or equal to the difference between P _l1 (t) and P _LSmax , it means that the energy storage unit 33 can discharge at full power at this time. To meet the demand of the important load 34 , keep the current states of the power sources and loads unchanged, so as to maintain the power balance of the microgrid system 3 .

Step 305, controlling the start-up of the micro-turbine power generation unit.

Step 306, calculate the sum of P _l1 (t) and P _l2max .

Specifically, when the energy management system 1 judges that the sum of P _PV (t) and P _WP (t) is greater than or equal to P _l1 (t), it calculates the sum of P _l1 (t) and P _l2max .

Step 307, comparing the sum of PP _PV (t) and P _WP (t) with the sum of P _l1 (t) and P _l2max , if the sum of PP _PV (t) and P _WP (t) If the sum is less than the sum of P _l1 (t) and P _l2max , execute step 308; otherwise, execute step 309.

Specifically, if the energy management system 1 judges that the sum of the P _PV (t) and P _WP (t) is less than the sum of the P _l1 (t) and P _l2max , it means that the output power of the photovoltaic power generation unit 31 at this time and If the sum of the output power of the wind power generation unit 32 cannot meet the demand of the important load 34 and the general controllable load 36 at the same time, the micro-turbine power generation unit 35 can be turned off, and a part of the general controllable load 36 can be controlled and put into the microgrid system 3 (i.e. execute step 308).

If the energy management system 1 judges that the sum of the P _PV (t) and the P _WP (t) is greater than or equal to the sum of the P _l1 (t) and P _l2max , it means that the output power of the photovoltaic power generation unit 31 and the wind force The sum of the output power of the generating unit 32 can meet the demand of the important load 34 and the demand of the general controllable load 36 at the same time, then it can be further judged whether the current energy storage unit 33 has reached the rated power, in order to adjust the use of each power supply or load ( That is, step 309 and subsequent steps are executed).

Step 308, controlling the shutdown of the micro-turbine power generation unit, and controlling part of the general controllable loads to be put into the micro-grid system.

Specifically, when the sum of the output power of the photovoltaic power generation unit 31 and the output power of the wind power generation unit 32 cannot meet the demand of the important load 34 and the demand of the general controllable load 36 at the same time, the energy management system 1 shuts down the micro-turbine power generation unit 35 , and put some general controllable loads into the microgrid system 3, which can minimize the running time of the micro-turbine power generation unit 35, and is suitable for occasions where the running time of the micro-turbine is limited due to environmental or energy constraints.

Step 309, calculate the sum of P _l1 (t), P _l2max and P _LSmax .

Step 310, comparing the sum of P _PV (t) and P _WP (t) with the sum of P _l1 (t), P _l2max and P _LSmax , if the sum of P _PV (t) and P _WP ( If the sum of t) is less than the sum of P _l1 (t), P _l2max and P _LSmax , execute step 311; otherwise, execute step 312.

Specifically, if the energy management system 1 judges that the sum of _PPV (t) and P _WP (t) is less than the sum of P _l1 (t), P _l2max and P _LSmax , it means that the photovoltaic power generation unit 31 at this time The sum of the output power and the output power of the wind power generation unit 32 can satisfy the demand of the important load 34 and the demand of the general controllable load 36 at the same time, but the energy storage unit 33 does not reach the rated power, then all the general controllable loads 36 are controlled to be put into the described Microgrid system 3 (that is, step 311 is executed).

If the energy management system 1 judges that the sum of the _PPV (t) and P _WP (t) is greater than or equal to the sum of the P _l1 (t), P _l2max and P _LSmax , it means that the output of the photovoltaic power generation unit 31 at this time is The sum of the output power of power and wind power generation unit 32 can satisfy the demand of important load 34 and the demand of general controllable load 36 simultaneously, but energy storage unit 33 has reached rated power, then can reduce the output power of wind power generation unit 32 (namely Execute step 312).

Step 311, controlling all general controllable loads to be put into the microgrid system.

Step 312, reducing the operating active power P _WP (t) of the wind turbine grid-connected inverter of the wind power generation unit.

The energy management system 1 can also control the micro-turbine power generation unit to shut down according to the comparison result of the SOC detection value with SOC _max and SOC _min .

The control process 3 will be described in detail below in conjunction with FIG. 4 and FIG. 1 . As shown in Figure 4, during the operation of the isolated microgrid, when the energy management system 1 determines that the SOC detection value is greater than or equal to SOC _max , the control process 3 is executed, and the control process 3 includes the following steps:

Step 401, controlling the micro-turbine power generation unit to shut down.

When the energy management system 1 determines that the current remaining power of the energy storage unit 33 reaches or exceeds the upper limit of the remaining power, in order to reduce the running time of the micro-turbine, the micro-turbine generating unit 35 is controlled to be turned off.

Step 402, calculate the sum of _PPV (t) and _PWP (t).

Step 403, comparing the sum of PP _PV (t) and P _WP (t) with P _l1 (t), if the sum of PP _PV (t) and P _WP (t) is greater than P _l1 (t) , execute step 404, otherwise, keep the current states of the power sources and loads unchanged.

Specifically, if the energy management system 1 judges that the sum of _{PPV (t) and PWP (t) is greater than or equal to P l1 ( t} ), it means that the output power of the photovoltaic power generation unit 31 is different from that of the wind power generation unit 32 at this time. The sum of the output power can meet the demand of the important load 34 , and the energy storage unit 33 is in the charging state, then the energy management system 1 can input some general controllable loads 36 (that is, execute step 404 ).

If the energy management system 1 judges that the sum of P _PV (t) and P _WP (t) is less than P _l1 (t), it means that the sum of the output power of the photovoltaic power generation unit 31 and the output power of the wind power generation unit 32 cannot satisfy the important The demand of the load 34, the energy storage unit 33 is in the discharge state, and the current energy storage unit 33 has a large amount of remaining power (that is, the SOC detection value is greater than or equal to SOC _max ), then the energy management system 1 can maintain each of the microgrid system 3 The current state of the power source (ie photovoltaic power generation unit 31 and wind power generation unit 32 ) and load (ie important load 34 and general controllable load 36 ) remains unchanged, so that the energy storage unit 33 is discharged and operated.

In step 404, the control part generally controls the load input into the microgrid system.

From the above control process, it can be seen that when the microgrid operates in an isolated grid, the micro-turbine power generation unit 35 is in a hot standby state. When the sum of the output power of the photovoltaic power generation unit 31 and the wind power generation unit 32 does not meet the demand of the important load 34, the energy storage unit 33 is firstly discharged to provide power for the load. When the remaining power of the energy storage unit 33 was lower than the lower limit of the remaining power, the micro-combustion engine generating unit 35 was controlled to start, so that the output power of the micro-combustion engine generating unit 35 was equal to the sum of the important load power and the charging power of the energy storage unit 33, thereby It not only charges the energy storage unit 33, but also provides the required power for the important load 34.

When the electric quantity of the energy storage unit 33 reaches the upper limit of the remaining electric quantity, the micro-combustion engine generating unit 35 is turned off, and the energy storage unit 33 provides electric power for the load.

When the sum of the output power of the photovoltaic power generation unit 31 and the wind power generation unit 32 is greater than the demand of the load, and the energy storage unit 33 has reached the rated power, the output power of the wind power generation unit 32 is reduced.

In the present invention, a micro-gas turbine power generation unit is set in the micro-grid system. When the micro-grid system operates in an isolated network, if the output of the photovoltaic power generation unit and the wind power generation unit is insufficient, the micro-gas turbine power generation unit can be started to provide power supply for the load. Reduce the energy storage capacity of the battery of the energy storage unit, thereby reducing environmental pollution, reducing the construction and operation and maintenance costs of the microgrid, and improving the reliability of the isolated grid operation of the microgrid.

In the grid-connected operation mode of the micro-grid system, the voltage and frequency of the micro-grid system can be guaranteed by the main grid. The control process of the grid-connected operation of the micro-grid system is described in detail from the two aspects of active power-frequency control and reactive power-voltage control. illustrate.

When the microgrid system is connected to the grid, there is active power exchange between the microgrid and the large grid, and the power flow direction is bidirectional. In order to ensure the safe operation of the microgrid, it is necessary to set the microgrid according to the specific conditions of the local distribution network The upper and lower limits of the power exchanged with the large grid (the upper and lower limits of the exchanged power between the microgrid and the large grid are the upper limit of the PCC point active power P _PCCmax and the lower limit of the PCC point active power P _PCCmin ), the micro grid needs to be within the above P _PCCmax and P _PCCmin operating within the switching power range between.

When the microgrid is connected to the grid, the large grid operates normally, the bypass switch K7 is closed, and the grid-connected switch K9 is closed. At this time, the photovoltaic power generation unit 31 and the wind power generation unit 32 in the microgrid system 3 output at maximum power. The detection system 2 detects the active power P _PCC (t) of the common connection point PCC point in real time. After the energy management system 1 receives the P _PCC (t) sent by the detection system 2, it compares P _PCC (t) with the upper limit of the PCC point active power P _PCCmax is compared with the lower limit of PCC point active power P _PCCmin , if P _PCC (t) is greater than or equal to P _PCCmax , then execute control process 4 (control process 4 will be described in detail later), if P _PCC (t) is less than or equal to P _PCCmin , the control flow 5 is executed (the control flow 5 will be described in detail later).

Further, the detection system 2 is also used to detect the active power P _PCC (t) of the common connection point PCC and the active power P _DG (t) of the micro-turbine power generation unit. The energy management system 1 is also used for receiving the P _PCC (t) and _PDG (t) sent by the detection system 2, and according to the P _PCC (t), P _DG (t) and the preset PCC point active power upper limit P _PCCmax , to control the shutdown of the micro-turbine power generation unit. The detection system 2 is also used to detect the grid-connected power Pb(t) of the energy storage unit, and the energy management system 1 is also used to adjust the operating status of each power source in the microgrid system 3 according to the current P _PCC (t).

The control process 4 will be described in detail below in conjunction with FIG. 5 and FIG. 1 . As shown in Figure 5, during the grid-connected operation of the microgrid, when the energy management system 1 determines that P _PCC (t) is greater than or equal to P _PCCmax , the control process 4 is executed, and the control process 4 includes the following steps:

Step 501, judge whether the active power _PDG (t) of the micro-gas turbine power generation unit is greater than 0, if _PDG (t) is greater than 0, execute step 502, otherwise, execute step 504.

Specifically, if the energy management system 1 judges that P _DG (t) is greater than 0, indicating that the current micro-turbine power generation unit 35 is in the running state, it is necessary to shut down the micro-gas turbine power generation unit 35 to reduce P _PCC (t) (i.e., execute Step 502).

If the energy management system 1 judges that _PDG (t) is not greater than 0, that is to say, _PDG (t) is equal to 0, indicating that the current micro-turbine power generation unit 35 is in a closed state, and further adjustment of the grid-connected power Pb of the energy storage unit is required (t) to reduce P _PCC (t) (that is, execute step 504).

Step 502, controlling the micro-turbine power generation unit to shut down.

Step 503, compare P _PCC (t) with P _PCCmax , if P _PCC (t) is greater than or equal to P _PCCmax , then perform step 504, otherwise, compare P _PCC (t) with the lower limit of PCC point active power P _PCCmin , when _{PPCC (t) is less than or equal to PPCCmin ,} the control process 5 is executed.

Specifically, if the energy management system 1 judges that P _PCC (t) is greater than or equal to P _PCCmax , it means that the active power P _PCC (t) at the PCC point is still too high after the micro-turbine power generation unit 35 is turned off, and further adjustment of the storage Energy unit grid-connected power Pb(t) to reduce P _PCC (t) (that is, execute step 504).

If the energy management system 1 judges that P _PCC (t) is less than P _PCCmax , indicating that the active power of the current PCC point is lower than the upper limit of the active power of the PCC point, then compare P _PCC (t) with the lower limit of the active power of the PCC point P _PCCmin , if P If _PCC (t) is less than or equal to P _PCCmin , then control flow 5 is executed.

Step 504, adjusting the grid-connected power Pb(t) of the energy storage unit.

Specifically, the energy management system 1 can be based on the PCC point active power upper limit P _PCCmax , important load active power P _l1 (t), general controllable load active power P _l2 (t), photovoltaic power generation unit grid-connected power P _V (t) and the grid-connected power P _W (t) of the wind power generation unit to adjust the grid-connected power Pb(t) of the energy storage unit.

Step 505, compare Pb(t) with the set rated power of the energy storage unit -P _Cnet (t) in the charging state, if Pb(t) is less than -P _Cnet (t), then execute step 506, otherwise, keep The current status of each power source and load remains unchanged.

Specifically, if the energy management system 1 judges that Pb(t) is less than -P _Cnet (t), it means that the grid-connected power of the energy storage unit exceeds the rated power of the energy storage unit at this time (in the charging state), and then controls the energy storage unit 33 Run at the rated power, and further reduce the photovoltaic grid-connected power PV (t) (that is, execute steps _506-508 ).

If the energy management system 1 judges that Pb(t) is greater than or equal to -P _Cnet (t), it means that the grid-connected power of the energy storage unit does not exceed the rated power of the energy storage unit at this time (in the charging state), then maintain the current The state of the load does not change.

Step 506, controlling the energy storage unit to run at rated power.

Specifically, the energy management system 1 makes Pb(t) equal to -P _Cnet (t).

In steps _507-508 , the grid-connected power PV (t) of the photovoltaic power generation unit is reduced to zero.

Specifically, the energy management system 1 gradually lowers the grid-connected power PV ( _t ) of the photovoltaic power generation unit until it drops to zero.

Step 509, compare P _PCC (t) with P _PCCmax , if P _PCC (t) is greater than or equal to P _PCCmax , then perform step 510, otherwise, compare P _PCC (t) with the PCC point active power lower limit P _PCCmin , when _{PPCC (t) is less than or equal to PPCCmin ,} the control process 5 is executed.

Specifically, the energy management system 1 judges whether the current P _PCC (t) is still greater than or equal to the PCC point active power upper limit P _PCCmax after _reducing the grid-connected power PV (t) of the photovoltaic power generation unit to 0, and if so, Then further limit the grid-connected power of the wind power generation unit (that is, execute steps 510-511).

If P _PCC (t) is less than P _PCCmax , it means that the active power of the current PCC point is lower than the upper limit of the active power of the PCC point, then compare P _PCC (t) with the lower limit of the active power of the PCC point P _PCCmin , and when P _PCC (t) is less than or When it is equal to P _PCCmin , the control process 5 is executed.

Steps 510-511, reducing the grid-connected power P _W (t) of the wind power generation unit to zero.

Specifically, the energy management system 1 gradually lowers the grid-connected power P _W (t) of the wind power generation unit until it drops to zero.

Further, the detection system 2 is also used to detect the grid-connected power Pb(t) of the energy storage unit and the grid-connected power P _W (t) of the wind power generation unit. The energy management system 1 is also used to receive the P _PCC (t), P _W (t) and Pb (t) sent by the detection system 2 when the microgrid system is connected to the grid, and according to the P _PCC (t), P _W (t), Pb(t), the preset lower limit of the active power of the PCC point P _PCCmin and the set rated power of the energy storage unit P _Cnet (t) in the discharge state, control the start of the micro-turbine power generation unit 35 .

The control process 5 will be described in detail below in conjunction with FIG. 6 and FIG. 1 . As shown in Figure 6, during the grid-connected operation of the microgrid, when the energy management system 1 determines that P _PCC (t) is less than or equal to P _PCCmin , the control process 5 is executed, and the control process 5 includes the following steps:

Step 601, judge whether P _W (t) is 0, if P _W (t) is equal to 0, then execute step 602, otherwise, execute step 603.

Specifically, if the energy management system 1 determines that P _W (t) is 0, it means that the wind power generation unit 31 is in the off state at this time, and then starts the wind power generation unit 31 to increase _PPCC (t) (that is, execute step 602 ).

If the energy management system 1 judges that P _W (t) is not 0, it means that the wind power generation unit 31 is running at this time, and further judges whether the wind power generation unit 32 is running in the maximum output power mode (that is, executes step 603 ).

Step 602, controlling the wind power generation unit to start.

Step 603, judge whether the wind power generation unit is in MPPT (Maximum Power Point Tracking) mode, if yes, execute step 605, otherwise, execute step 604.

Specifically, if the energy management system 1 judges that the wind power generation unit 32 is in the MPPT mode, it judges again whether the active power of the current PCC point is still lower than or equal to the lower limit of the active power of the PCC point (that is, executes step 605 ).

If the energy management system 1 determines that the wind power generation unit 32 is not in the MPPT mode, it controls the wind power generation unit 32 to operate in the MPPT mode (that is, executes step 604 ).

Step 604, controlling the wind power generation unit to run in MPPT mode.

Step 605, compare _{PPCC (t) with PPCCmin ,} if _{PPCC (t) is less than or equal to PPCCmin ,} then execute step 606, otherwise, keep the current status of each power source and load unchanged.

Specifically, if the energy management system 1 judges that P _PCC (t) is less than or equal to P _PCCmin , it means that even if the wind power generation unit 32 operates at the maximum output power, the current active power at the PCC point is still too low, and then further judge the photovoltaic power generation unit state (i.e. execute step 606).

If the energy management system 1 judges that P _PCC (t) is greater than P _PCCmin , it means that after the wind power generation unit 32 is controlled to operate in MPPT mode, the current active power at the PCC point is higher than the lower limit of the active power at the PCC point, then the current power sources and The state of the load does not change.

Step 606, judging whether the grid-connected power PV ( _t ) of the photovoltaic power generation unit is 0, if PV ( _t ) is equal to 0, execute step 607, otherwise, execute step 608.

Specifically, if the energy management system 1 judges that PV ( _t ) is equal to 0, indicating that the photovoltaic power generation unit 31 is currently off, the photovoltaic power generation unit 31 is started to increase the active power of the PCC point (that is, step 607 is executed).

If the energy management system 1 judges that PV ( _t ) is not equal to 0, it means that the photovoltaic power generation unit 31 is currently running, and then further judges whether the photovoltaic power generation unit 31 is running in the maximum output power mode (that is, executes step 608 ).

Step 607, controlling the photovoltaic power generation unit to start.

Step 608, determine whether the photovoltaic power generation unit is in MPPT mode, if yes, execute step 610, otherwise, execute step 609.

Specifically, if the energy management system 1 judges that the photovoltaic power generation unit 31 is in the MPPT mode, it judges again whether the active power of the current PCC point is still lower than or equal to the lower limit of the active power of the PCC point (that is, executes step 610 ).

If the energy management system 1 determines that the photovoltaic power generation unit 31 is not in the MPPT mode, it controls the photovoltaic power generation unit 31 to operate in the MPPT mode (that is, executes step 609 ).

Step 609, controlling the photovoltaic power generation unit to operate in MPPT mode.

Step 610, compare _{PPCC (t) with PPCCmin ,} if _{PPCC (t) is less than or equal to PPCCmin ,} then execute step 611, otherwise, keep the current status of each power source and load unchanged.

Specifically, if the energy management system 1 judges that P _PCC (t) is less than or equal to P _PCCmin , it means that even though the wind power generation unit 32 and the photovoltaic power generation unit 31 are operating at the maximum output power, the active power at the current PCC point is still too low, then Further adjust the grid-connected power Pb(t) of the energy storage unit (that is, execute step 611).

If the energy management system 1 judges that P _PCC (t) is greater than P _PCCmin , it means that after controlling both the wind power generation unit 32 and the photovoltaic power generation unit 31 to operate in the MPPT mode, the current active power of the PCC point is higher than the lower limit of the active power of the PCC point. Then keep the current status of each power source and load unchanged.

Step 611, adjusting the grid-connected power Pb(t) of the energy storage unit.

Specifically, the energy management system 1 can be based on the lower limit of PCC point active power P _PCCmin , the active power of important loads P _l1 (t), the active power of general controllable loads P _l2 (t), and the grid-connected power of photovoltaic power generation units P _V (t) and the grid-connected power P _W (t) of the wind power generation unit to adjust the grid-connected power Pb(t) of the energy storage unit.

Step 612, compare Pb(t) with the set rated power P _Cnet (t) of the energy storage unit in the discharge state, if Pb(t) is greater than P _Cnet (t), then execute step 613, otherwise, keep the current The status of the source and load does not change.

Specifically, if the energy management system 1 judges that Pb(t) is greater than P _Cnet (t), it means that the grid-connected power of the energy storage unit exceeds the rated power of the energy storage unit at this time (in the discharge state), and then controls the energy storage unit 33 to Run at the rated power, and further start the micro-turbine power generation unit (that is, execute step 613).

If the energy management system 1 judges that Pb(t) is less than or equal to P _Cnet (t), it means that the grid-connected power of the energy storage unit does not exceed the rated power of the energy storage unit at this time (in the discharge state), then the current power supply and load status remains unchanged.

613. Control the energy storage unit to run at P _Cnet (t), and control the micro-turbine power generation unit to start.

The reactive power-voltage control process will be described in detail below.

When the microgrid is connected to the grid, the reactive power of the PCC point will affect the voltage of the PCC point. In order to ensure the safe connection of the microgrid to the large power grid, it is necessary to control the reactive power-voltage of the PCC point. Controlled by power factor control.

The constant power factor control method means that the active power runs between the upper and lower limits during the grid-connected operation of the microgrid. Then within this interval, the power factor of the PCC point remains within the set value. If the energy management system sets the power factor of the PCC point to cos(φ), and the active power of the PCC point is P _PCC (t).

The energy management system 1 calculates the reactive power Q _b (t) of the energy storage system, and sends the calculated reactive power Q _b (t) of the energy storage system to the energy storage unit 33 to control the energy storage unit 33 according to the energy storage system The system reactive power Q _b (t) is adjusted.

If cos(φ)>0, the reactive power source in the microgrid system is an energy storage system, and the reactive power Q _b (t) of the energy storage system can be calculated according to formula (1):

${\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; PCC</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\sqrt{{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; PCC</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&phi;</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; PCC</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

Among them, Q _b (t) is the reactive power of the energy storage system; Q _PCC (t) is the reactive power of the PCC point; P _PCC (t) is the active power of the PCC point.

If cos(φ)<0, the reactive power source in the microgrid system is an energy storage system, and the reactive power Q _b (t) of the energy storage system can be calculated according to formula (2):

${\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; b</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; Q</span>}}_{\mathrm{<span\; class="notranslate">\; PCC</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span><span\; class="notranslate">\; -</span>\sqrt{{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; PCC</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>}{\mathrm{<span\; class="notranslate">\; cos</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; \&phi;</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; PCC</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; )</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

Among them, Q _b (t) is the reactive power of the energy storage system; Q _PCC (t) is the reactive power of the PCC point; P _PCC (t) is the active power of the PCC point.

In addition to the aforementioned grid-connected operation mode and isolated grid operation mode, the microgrid system also includes the following operating states: switching from grid-connected mode to isolated grid mode, switching from isolated grid mode to grid-connected mode, and black start mode. Black start means that after the entire system is out of service due to a fault, the system is completely blacked out (the isolated small power grid is still in operation), and it is in a completely "black" state without relying on the help of other networks. Start, drive the generating set without self-starting ability, gradually expand the scope of system recovery, and finally realize the recovery of the entire system.

The working process of the microgrid system in the grid-connected operation mode and the isolated grid operation mode is as mentioned above, and will not be repeated here. The working process in the startup mode is described in detail separately.

When the grid-connected mode is switched to the isolated grid mode, the grid-connected switch K9 is disconnected to simulate a power outage of the grid. At this time, the operating status of the large power grid is first identified through the PCS. When the PCS detects that the large power grid is in a fault state, the PCS controls its PCC The supporting static switch K8 is disconnected, and at the same time, the working mode of the PCS is automatically and smoothly switched from the P-Q control mode (voltage and frequency follow the grid control mode) to the V/f control mode (voltage/frequency control mode based on droop characteristics). During the switching process, the operating status of other power sources remains unchanged, thereby realizing the switching of the microgrid system from the grid-connected mode to the isolated grid mode.

When switching from the isolated grid mode to the grid-connected mode, close the grid-connected switch K9 to simulate the grid status returning to normal. At this time, after the PCS automatic identification technology detects that the grid status has returned to normal, the PCS detects the voltage amplitude and frequency on both sides of the static switch K8 And the synchronous conditions of the phase angle, while continuously controlling the V and f signals output by itself according to the deviation, so as to realize the synchronization between the independent system of the microgrid and the grid. When the two meet the synchronization conditions, the PCS controls the static switch K8 to close, and at the same time, the operation mode of the PCS is automatically and smoothly switched from the V/f mode to the P-Q mode, completing the switching mode of the microgrid from isolated grid to grid-connected.

During the black start, the grid-connected switch K9 is turned off, and at the same time, all power sources and loads in the microgrid system are disconnected from the busbar, which requires the microgrid to have black start capability. When the microgrid system is in a completely black state, in order to protect the equipment, all the circuit breakers are disconnected first, and then a black start is performed according to a certain procedure. Therefore, the microgrid is simulated to be in a completely black state by disconnecting the circuit breakers. break away. That is, confirm that all power distribution switches K1-K6 are in the disconnected state, and then first start the energy storage unit 33 to make it run in V/f mode, establish the voltage and frequency reference values for isolated grid operation, and when the system reaches a steady state , and then connect to other power sources and loads in the system one after another, and finally realize the black start of the microgrid.

The invention utilizes the energy storage bidirectional converter to realize the seamless switching of microgrid separation and grid connection, and utilizes the characteristics of high reliability and easy control of the micro-gas turbine to make it an energy supply unit of the micro-grid, which not only improves The reliability of the power supply of the microgrid can effectively reduce the battery capacity of the energy storage unit, thereby reducing the environmental pollution of waste batteries, reducing the investment and operation costs, enabling the comprehensive utilization of various new energy sources, and improving the adaptability of the microgrid system. It takes about 15 minutes for the micro-turbine power generation unit to enter the full-load state from the cold standby state. Considering the need to stabilize the grid shock, the energy storage unit can guarantee the power demand of the micro-grid system as long as it meets the full-load operation of the micro-grid for about 2 to 4 hours. , with the micro-turbine power generation unit, it can meet the long-term stable operation of the micro-grid in the isolated grid state.

It can be understood that, the above embodiments are only exemplary embodiments adopted for illustrating the principle of the present invention, but the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also regarded as the protection scope of the present invention.

Claims (11)

1. a micro grid control system, comprise: EMS, detection system and micro-grid system, micro-grid system comprises: photovoltaic generation unit, wind power generation unit, energy-storage units and important load, and detection system is for detecting the remaining capacity SOC of energy-storage units, the photovoltaic combining inverter operation active-power P of photovoltaic generation unit _pVt the blower fan combining inverter of (), wind power generation unit runs active-power P _wP(t) and important load active-power P _l1t (), is characterized in that, described micro-grid system also comprises miniature combustion engine generator unit;

EMS is used for, and when micro-grid system isolated power grid, receives SOC detected value, P that detection system sends _l1(t), P _pV(t) and P _wPt (), by SOC detected value and the SOC upper limit SOC preset _maxwith SOC lower limit SOC _mincompare, and calculate P _pV(t) and P _wP(t) sum; And, according to comparative result, P _pV(t) and P _wP(t) sum and P _l1t (), controls miniature combustion engine generator unit and starts, or, according to comparative result, P _pV(t) and P _wP(t) sum, P _l1the specified active-power P of PCS of (t) and default energy-storage units _lSmax, control miniature combustion engine generator unit and start.

2. the system as claimed in claim 1, is characterized in that, described micro-grid system also comprises general controllable burden;

Described EMS specifically for, when judging that SOC detected value is less than or equal to SOC _mintime, excise general controllable burden, calculate P _pV(t) and P _wP(t) sum, and by described P _pV(t) and P _wP(t) sum and P _l1t () is compared, if described P _pV(t) and P _wPt () sum is less than P _l1t (), then control miniature combustion engine generator unit and start; When judging that SOC detected value is greater than SOC _minand be less than SOC _maxtime, calculate P _pV(t) and P _wPt () sum, by described P _pV(t) and P _wP(t) sum and P _l1t () is compared, if described P _pV(t) and P _wPt () sum is less than P _l1t (), then calculate P _l1(t) and P _lSmaxdifference, and by described P _pV(t) and P _wP(t) sum and described P _l1(t) and P _lSmaxdifference compare, if described P _pV(t) and P _wPt () sum is less than described P _l1(t) and P _lSmaxdifference, then control miniature combustion engine generator unit and start.

3. the system as claimed in claim 1, is characterized in that, described micro-grid system also comprises general controllable burden;

Described EMS also for, control miniature combustion engine generator unit according to described comparative result and close, or, according to described comparative result, P _pV(t) and P _wP(t) sum, P _l1(t) and the specified active-power P of general controllable burden preset _l2max, control miniature combustion engine generator unit and close.

4. system as claimed in claim 3, is characterized in that, described EMS specifically for, when judging that SOC detected value is more than or equal to SOC _maxtime, control miniature combustion engine generator unit and close, calculate P _pV(t) and P _wP(t) sum, and by described P _pV(t) and P _wP(t) sum and P _l1t () is compared, if described P _pV(t) and P _wPt () sum is more than or equal to P _l1(t), then the general controllable burden of control section drops into described micro-grid system; When judging that SOC detected value is greater than SOC _minand be less than SOC _max, and described P _pV(t) and P _wPt () sum is more than or equal to P _l1time (t), calculate P _l1(t) and P _l2maxsum, and by described P _pV(t) and P _wP(t) sum and described P _l1(t) and P _l2maxsum is compared, if described P _pV(t) and P _wPt () sum is less than described P _l1(t) and P _l2maxsum, then controls miniature combustion engine generator unit and close, and the general controllable burden of control section drops into described micro-grid system.

5. system as claimed in claim 4, is characterized in that, described EMS also for, if described P _pV(t) and P _wPt () sum is more than or equal to described P _l1(t) and P _l2maxsum, then calculate P _l1(t), P _l2maxand P _lSmaxsum, and by described P _pV(t) and P _wP(t) sum and describedly calculate P _l1(t), P _l2maxand P _lSmaxsum is compared, if described P _pV(t) and P _wPt () sum is less than described P _l1(t), P _l2maxand P _lSmaxsum, then control all general controllable burdens and drop into described micro-grid system.

6. system as claimed in claim 5, is characterized in that, described EMS also for, if described P _pV(t) and P _wPt () sum is more than or equal to described P _l1(t), P _l2maxand P _lSmaxsum, then the blower fan combining inverter reducing wind power generation unit runs active-power P _wP(t).

7. the system as described in any one of claim 1-6, is characterized in that, described detection system also for, when micro-grid system is incorporated into the power networks, detect points of common connection PCC point active-power P _pCCt the miniature combustion engine of () and miniature combustion engine generator unit runs active-power P _dG(t);

Described EMS also for, when micro-grid system is incorporated into the power networks, receive detection system send P _pCC(t) and P _dG(t), and according to P _pCC(t), P _dG(t) and the PCC point active power upper limit P preset _pCCmax, control miniature combustion engine generator unit and close.

8. system as claimed in claim 7, is characterized in that, described EMS specifically for, by P _pCC(t) and P _pCCmaxcompare, work as P _pCCt () is more than or equal to P _pCCmaxtime, judge P _dGt whether () be greater than 0, if P _dGt () is greater than 0, then control miniature combustion engine generator unit and close.

9. system as claimed in claim 8, is characterized in that, described detection system also for, detect the grid-connected power P b (t) of energy-storage units;

Described EMS also for, after control miniature combustion engine generator unit is closed, by P _pCC(t) and P _pCCmaxcompare, if P _pCCt () is more than or equal to P _pCCmax, then regulate the grid-connected power P b (t) of energy-storage units, and by Pb (t) and the energy-storage units rated power-P under the charged state arranged _cnett () is compared, if Pb (t) is less than-P _cnett (), then control energy-storage units with rated power operation, by grid-connected for photovoltaic generation unit power P _vt () is reduced to 0, and by P _pCC(t) and P _pCCmaxcompare, if P _pCCt () is more than or equal to P _pCCmax, then by grid-connected for wind power generation unit power P _wt () is reduced to 0.

10. system as claimed in claim 8, is characterized in that, described detection system also for, detect the grid-connected power P b (t) of energy-storage units and the grid-connected power P of wind power generation unit _w(t);

Described EMS also for, when micro-grid system is incorporated into the power networks, receive detection system send P _pCC(t), P _w(t) and Pb (t), and according to P _pCC(t), P _w(t), Pb (t), the PCC point active power lower limit P preset _pCCminwith the energy-storage units rated power P under the discharge condition arranged _cnett (), controls miniature combustion engine generator unit and starts.

11. systems as claimed in claim 10, is characterized in that, described EMS specifically for, work as P _pCCt () is less than or equal to P _pCCmintime, if judge P _wt () is 0, then control wind power generation unit and start, and judge whether wind power generation unit is in MPPT pattern, if so, then by P _pCC(t) and P _pCCmincompare, if P _pCCt () is less than or equal to P _pCCmin, then the grid-connected power P of photovoltaic generation unit is judged _vt whether () be 0, if so, then starts photovoltaic generation unit, and judge whether photovoltaic generation unit is in MPPT pattern, if so, then by P _pCC(t) and P _pCCmincompare, if P _pCCt () is less than or equal to P _pCCmin, then regulate the grid-connected power P b (t) of energy-storage units, and by Pb (t) and the energy-storage units rated power P under the discharge condition arranged _cnett () is compared, if Pb (t) is greater than P _cnett (), then control energy-storage units with P _cnett () is run, and control the startup of miniature combustion engine generator unit.