CN116505580A - Micro-grid control system and method - Google Patents
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/381—Dispersed generators
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J13/00—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network
- H02J13/00002—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network characterised by monitoring
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J13/00—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network
- H02J13/00004—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network characterised by the power network being locally controlled
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J13/00—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network
- H02J13/00006—Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network characterised by information or instructions transport means between the monitoring, controlling or managing units and monitored, controlled or operated power network element or electrical equipment
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/04—Circuit arrangements for ac mains or ac distribution networks for connecting networks of the same frequency but supplied from different sources
- H02J3/06—Controlling transfer of power between connected networks; Controlling sharing of load between connected networks
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/388—Islanding, i.e. disconnection of local power supply from the network
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
- H02J2203/10—Power transmission or distribution systems management focussing at grid-level, e.g. load flow analysis, node profile computation, meshed network optimisation, active network management or spinning reserve management
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
- H02J2300/20—The dispersed energy generation being of renewable origin
- H02J2300/22—The renewable source being solar energy
- H02J2300/24—The renewable source being solar energy of photovoltaic origin
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
- H02J2300/20—The dispersed energy generation being of renewable origin
- H02J2300/28—The renewable source being wind energy
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Abstract
The invention relates to the technical field of power grids, in particular to a micro-grid control system and a micro-grid control method, comprising the following steps: a microgrid master controller, a plurality of microgrids, the microgrids comprising: the grid-connected terminal is connected with the main power grid, the user terminal comprises an energy storage system and a power generation system, and the power generation system comprises: photovoltaic power generation system and wind power generation system. The micro-grid controller is connected with the energy storage system, the power generation system and the grid connection end; the micro-grid master controller is electrically connected with the micro-grid controller of each micro-grid in the plurality of micro-grids; the micro-grid controller is used for monitoring the running state of the micro-grid, sending the running state to the micro-grid master controller and receiving a control instruction of the micro-grid master controller so as to control the micro-grid to run in one of a grid-connected running mode, a risk running mode, a grid-isolated running mode and a grid-connected running mode. The invention can realize the stable switching of the micro-grid operation mode.
Description
Technical Field
The invention relates to the technical field of power grids, in particular to a micro-grid control system and method.
Background
Along with the increasing increase of energy consumption, the energy shortage, the low utilization rate and the environmental pollution are also becoming more and more severe, and the micro-grid becomes a main strategic means for developing the power industry and solving the energy problem by virtue of the flexibility, the high efficiency, the economy, the environmental protection, the energy diversity and the like. The micro-grid can integrate a large amount of distributed new energy to generate power, can solve the problems of energy exhaustion and environmental deterioration, and is an important component of a power distribution network in a future intelligent grid.
The operation control of the micro-grid must have the capability of stable switching under the grid-connected and isolated operation modes, and the existing micro-grid operation is mostly direct switching of two modes, and has single switching strategy and unstable operation. In order to realize smooth switching between two typical operation modes of a micro-grid, an operation strategy capable of reasonably switching smooth transition in a multi-operation-mode environment of the micro-grid is required, so that the power supply reliability of the micro-grid is improved.
Disclosure of Invention
The invention provides a micro-grid control system and a micro-grid control method, which can solve the problem that a micro-grid in the prior art cannot stably switch operation modes; meanwhile, the discharge power of the user side in the micro-grid is adaptively adjusted in real time, so that the power consumption of the grid-connected side is ensured to be in a planned demand range, and the power supply and demand balance of the user side is achieved; in addition, wind energy and solar energy are utilized to generate electricity to reduce the electricity generation cost and reduce the environmental pollution.
In order to achieve the above purpose, the invention adopts the following technical scheme:
a microgrid control system comprising: the micro-grid system comprises a micro-grid master controller and a plurality of micro-grids, wherein the micro-grids are connected through a power transmission line and a connecting line, and the micro-grid master controller is electrically connected with a micro-grid controller of each micro-grid in the micro-grids; the micro-grid controller is used for monitoring the running state of the micro-grid, sending the running state to the micro-grid master controller and receiving a control instruction of the micro-grid master controller so as to control the micro-grid to run in one running mode of a grid-connected running mode, a risk running mode, a grid-isolated running mode and a recovery grid-connected running mode;
the microgrid comprises: the system comprises a grid-connected end and a user end, wherein the grid-connected end is connected with a main power grid, the user end comprises an energy storage system and a power generation system, and the micro-power grid controller is connected with the energy storage system, the power generation system and the grid-connected end;
the micro-grid controller is used for acquiring the power consumption of the grid-connected end and the discharge power of the user end, acquiring a first critical power value of the power consumption exceeding the required amount of the grid-connected end and a second critical power value of the power inversion of the grid-connected end, and adaptively adjusting the discharge power of the user end according to the power consumption of the grid-connected end, the first critical power value and the second critical power value;
the discharging power of the user side comprises the discharging power of an energy storage system and the generating power of a generating system, and the generating system comprises: photovoltaic power generation system and wind power generation system.
Further, the micro-grid is provided with reactive compensation devices,
in the grid-connected operation mode, when the micro-grid is required to output reactive power, the reactive power compensation device controls the energy storage system to output reactive power, and the calculation formula of the output reactive power of the energy storage system is as follows:
Qb=－λUm·ΔU
wherein: qb is reactive compensation capacity; lambda is a compensation coefficient; um is the micro-grid busbar voltage; ΔU is the voltage deviation.
Further, the energy storage system is a hybrid energy storage system comprising a power-type energy storage system and an energy-type energy storage system, wherein power changes in a short time scale are regulated by the power-type energy storage system, and power changes in a long time scale are regulated by the energy-type energy storage system.
Further, the energy storage system comprises a plurality of energy storage units, wherein the output of each energy storage unit is distributed through a weighted distribution algorithm; the method comprises the following steps:
during charging, the output of each energy storage unit is distributed according to the percentage of the energy storage electric quantity consumed by each energy storage unit to the total energy storage electric quantity consumed;
and during discharging, distributing the output of each energy storage unit according to the percentage of the residual energy storage electric quantity of each energy storage unit to the total residual energy storage electric quantity.
Further, the micro grid master controller includes:
the risk operation mode control module is used for controlling the power flow direction among the micro-grids and controlling the load and the output of the transmission line and the power station;
the isolated network operation mode control module is used for controlling the plurality of micro-grids to be converted from a risk operation mode to an isolated network operation mode under the condition that one or more micro-grids in the plurality of micro-grids fail;
the grid-connected recovery operation mode control module is used for controlling the micro-grids to be converted from the isolated grid operation mode to the grid-connected recovery operation mode under the condition that the faults of the micro-grids are all eliminated;
and the grid-connected operation mode control module is used for controlling the plurality of micro-grids to be converted into a grid-connected operation mode from the recovery grid-connected operation mode.
Further, the isolated network operation mode includes:
under the condition that the unit fault exits from operation in the micro-grid, correspondingly cutting off the load of the micro-grid so as to maintain the power balance;
in the event of a line fault trip load in the microgrid, the output of the microgrid is correspondingly reduced to maintain power balance.
Further, the recovering the grid-connected operation mode includes:
reducing a voltage difference between each of the plurality of micro-grids and the main grid;
adjusting a frequency of each of the plurality of micro-grids such that the frequency of each micro-grid is lower than a frequency of the main grid;
the voltage of each of the plurality of micro-grids is adjusted such that the phase of the voltage of the main grid leads the phase of the voltage of each micro-grid.
Further, the reactive compensation device includes: the device comprises a detection module, a control operation module and a compensation output module, wherein the control operation module is connected with the detection module and the compensation output module.
A microgrid control method that is applied to a microgrid control system as described above, the microgrid control method comprising:
monitoring the running state of the micro-grid and sending the running state to the micro-grid master controller;
and receiving a control instruction of the micro-grid master controller to control the micro-grid to operate in one of a grid-connected operation mode, a risk operation mode, a grid-isolated operation mode and a grid-connected operation mode recovery operation mode.
Further, the micro-grid control method further includes:
collecting the power consumption of the grid-connected terminal and the discharge power of the user terminal, and obtaining a first critical power value of the power consumption exceeding the required quantity of the grid-connected terminal and a second critical power value of the power inversion of the grid-connected terminal;
and adaptively adjusting the discharge power of the user side according to the power consumption of the grid-connected side, the first critical power value and the second critical power value.
The invention has the beneficial effects that:
the method monitors the running state of the micro-grid through the micro-grid controller, sends the running state to the micro-grid master controller, and receives a control instruction of the micro-grid master controller so as to control the micro-grid to run in one running mode of a grid-connected running mode, a risk running mode, a grid-isolated running mode and a grid-connected running mode; smooth switching of the micro-grid operation mode is achieved.
The micro-grid controller adaptively adjusts the discharge power of the user side according to the power consumption of the grid-connected side, the first critical power value and the second critical power value, wherein the discharge power of the user side comprises the discharge power of an energy storage system and the power generation power of a power generation system; and the discharge power of the user side in the micro-grid is adaptively regulated in real time, so that the power consumption of the grid-connected side is ensured to be in a planned demand range, and the power supply and demand balance of the user side is achieved.
The power generation system of the present invention includes: the photovoltaic power generation system and the wind power generation system can obtain stable output by utilizing the complementarity of wind energy and solar energy, and the system has higher stability and reliability; meanwhile, under the condition of ensuring the same power supply, the battery capacity of the energy storage system can be reduced. In addition, compared with diesel engine power generation, the wind energy and solar energy are utilized to generate power, so that the power generation cost can be reduced, and the environmental pollution is reduced. Moreover, the wind energy and the solar energy are rich in resources and have great development potential.
Drawings
Fig. 1 is a schematic diagram of a micro-grid master controller connected to a micro-grid controller of the micro-grid control system of the present invention.
Detailed Description
Referring to fig. 1, the present invention relates to a micro-grid control system and a method thereof.
Micro-Grid (Micro-Grid) is also called as Micro-Grid, and refers to a small power generation and distribution system composed of a distributed power supply, an energy storage device, an energy conversion device, a load, a monitoring and protecting device and the like, and is used for supplying power to the load, so that the problem of power supply reliability is mainly solved.
The proposal of the micro-grid aims to realize flexible and efficient application of the distributed power supply and solve the problem of grid connection of the distributed power supply with huge quantity and various forms. The development and extension of the micro-grid can fully promote the large-scale access of the distributed power supply and the renewable energy sources, realize the high-reliability supply of various energy forms of loads, and be an effective way for realizing an active power distribution network, so that the traditional power grid is transited to the intelligent power grid.
Most of the power sources in the micro-grid are distributed power sources with smaller capacity, namely small units with power electronic interfaces.
Example 1
A microgrid control system comprising: the micro-grid system comprises a micro-grid master controller and a plurality of micro-grids, wherein the micro-grids are connected through a power transmission line and a connecting line, and the micro-grid master controller is electrically connected with a micro-grid controller of each micro-grid in the micro-grids; the micro-grid controller is used for monitoring the running state of the micro-grid, sending the running state to the micro-grid master controller and receiving a control instruction of the micro-grid master controller so as to control the micro-grid to run in one running mode of a grid-connected running mode, a risk running mode, a grid-isolated running mode and a recovery grid-connected running mode; the aim of the method is to realize the cyclic switching of four operation modes, namely a grid-connected operation mode, a risk operation mode, a isolated grid operation mode and a recovery grid-connected operation mode, ensure the stable switching of the micro-grid due to the addition of the risk operation mode and the recovery grid-connected operation mode, and improve the operation stability of the micro-grid.
The microgrid comprises: the system comprises a grid-connected end and a user end, wherein the grid-connected end is connected with a main power grid (the main power grid is also called a power distribution network or a large power grid, which means a power grid which receives electric energy from a power transmission network or a regional power plant and is distributed to various users in situ or step by step according to voltage through a power distribution facility), the user end comprises an energy storage system and a power generation system, and a micro-grid controller is connected with the energy storage system, the power generation system and the grid-connected end; the power generation system includes: the photovoltaic power generation system and the wind power generation system can obtain stable output by utilizing the complementarity of wind energy and solar energy, and the system has higher stability and reliability; meanwhile, under the condition of ensuring the same power supply, the battery capacity of the energy storage system can be reduced. In addition, compared with diesel engine power generation, the wind energy and solar energy are utilized to generate power, so that the power generation cost can be reduced, and the environmental pollution is reduced. Moreover, the wind energy and the solar energy are rich in resources and have great development potential.
The micro-grid controller is used for acquiring the power consumption of the grid-connected end and the discharge power of the user end, acquiring a first critical power value of the power consumption exceeding the required amount of the grid-connected end and a second critical power value of the power inversion of the grid-connected end, and adaptively adjusting the discharge power of the user end according to the power consumption of the grid-connected end, the first critical power value and the second critical power value; in this embodiment, the power consumption excess of the grid-connected end means that the power consumption of the grid-connected end exceeds the maximum value of the power consumption expected by a user, at this time, the operation load of the user end is excessive, the power demand is larger, and if the power consumption of the grid-connected end can be correspondingly adjusted or the power consumption of the power generation system can be increased, the power consumption of the grid-connected end can be reduced, and the user electricity fee can be saved. The grid-connected side power dumping refers to that the running load of the user side is reduced, the required load power is smaller than the generated power of the user side, and the generated power of the user side is excessive, so that the excessive generated/discharged power of the user side can be dumped to the main power grid. At this time, if the power generation/discharge power of the user terminal is not regulated, the redundant power will be consumed by the power supply system. Therefore, the embodiment ensures that the power consumption of the grid-connected terminal is within the planned demand range by adaptively adjusting the discharge power of the user terminal in the micro-grid in real time so as to achieve the power supply and demand balance of the user terminal.
The end regions of the distribution network in remote areas often have problems of insufficient reactive power and low voltage levels, resulting in increased losses in the supply transformers and transmission lines.
In this regard, the micro-grid according to this embodiment is provided with a reactive power compensation device, the reactive power compensation device includes: the system comprises a detection module, a control operation module and a compensation output module, wherein the detection module is used for detecting current information of a system, the control operation module is used for analyzing current information according to the detected current information, and the compensation output module is used for outputting a driving signal for enabling the energy storage system to send compensation current according to the current information. In particular, the method comprises the steps of,
in the grid-connected operation mode, when the micro-grid is required to output reactive power, the reactive power compensation device controls the energy storage system to output reactive power, and the calculation formula of the output reactive power of the energy storage system is as follows:
Qb=－λUm·ΔU
wherein: qb is reactive compensation capacity; lambda is a compensation coefficient; um is the micro-grid busbar voltage; ΔU is the voltage deviation. In practical engineering, because the structure of the power distribution network is complex, the reactance value of the system is difficult to calculate accurately, and therefore the value of lambda can be generally determined by actually measuring the reactive power variation of the grid-connected point of the micro-grid and the busbar voltage variation of the micro-grid on site.
According to the embodiment, the reactive voltage control capability of the micro-grid connected to the tail end of the power distribution network is utilized, the reactive power flow of the power distribution network is reduced, the voltage level of the tail end of the power distribution network is improved, the network loss is reduced, and the quality of the power distribution network is improved.
Further, the energy storage system is a hybrid energy storage system comprising a power-type energy storage system and an energy-type energy storage system, the power-type energy storage system comprising: super capacitor and flywheel, energy-type energy storage system includes: iron lithium batteries and lead acid batteries.
The hybrid energy storage system stabilizes fluctuation of distributed generation power through a hybrid energy storage power distribution algorithm, wherein the power distribution algorithm comprises the following steps: the power change in the short time scale is regulated by the power-type energy storage system and the power change in the long time scale is regulated by the energy-type energy storage system.
For example: setting the current output of wind and light as Pw.s, PM (t) as the energy storage output target value at t moment, simultaneously setting the power change value in unit time to measure by using the power change value Pk, taking Pk=Pw.s (ti) -Pw.s (ti-1), adopting a control algorithm to set a power change limit value Pkup,
when the absolute value of the power change is smaller than the limit value, the compensation power is regulated by the energy type energy storage system; when the absolute value of the power change is greater than the limit value, the remainder is regulated by the power storage system.
The power Pbat required to be regulated at the time t of the energy storage system is shown as a formula (1):
（1）
when the power variation value is smaller than the limit value, the compensation power is regulated by the energy type energy storage system; when the absolute value of the power change is larger than the limiting value, the power regulating value allocated to the energy type energy storage system is the sum of the regulating value at the previous moment and the maximum allowable power change value, and the rest part is regulated by the power type energy storage system.
The power Psc to be regulated by the power energy storage system at the time t is shown in the formula (2):
Psc（t）=PM（t）－Pbat（t） （2）
and for the selection of the power change rate limiting value Pkup, the power change rate limiting value Pkup is required to be adjusted according to the charge and discharge power limiting value and the SOC allowable range of the energy storage system.
Further, the energy storage system comprises a plurality of energy storage units, wherein the output of each energy storage unit is distributed through a weighted distribution algorithm; the method comprises the following steps:
during charging, the output of each energy storage unit is distributed according to the percentage of the energy storage electric quantity consumed by each energy storage unit to the total energy storage electric quantity consumed;
and during discharging, distributing the output of each energy storage unit according to the percentage of the residual energy storage electric quantity of each energy storage unit to the total residual energy storage electric quantity.
In this embodiment, energy storage charging and discharging management needs to be performed according to the charging and discharging power and the current state of charge of the energy storage system, and the principle is to meet the technical index of safety and stability of the energy storage unit, and the charging and discharging power does not exceed the allowable maximum charging and discharging power, so that overshoot and over-discharging of the storage battery are avoided. In order to ensure the standby capacity of the energy storage unit, when the SOC is large, a low-power charging and high-power discharging mode is adopted; when the SOC is small, a high-power charging and low-power discharging mode is adopted.
In this embodiment, the micro grid master controller includes:
the risk operation mode control module is used for controlling the power flow direction among the micro-grids and controlling the load and the output of the transmission line and the power station;
the isolated network operation mode control module is used for controlling the plurality of micro-grids to be converted from a risk operation mode to an isolated network operation mode under the condition that one or more micro-grids in the plurality of micro-grids fail;
the grid-connected recovery operation mode control module is used for controlling the micro-grids to be converted from the isolated grid operation mode to the grid-connected recovery operation mode under the condition that the faults of the micro-grids are all eliminated;
and the grid-connected operation mode control module is used for controlling the plurality of micro-grids to be converted into a grid-connected operation mode from the recovery grid-connected operation mode.
Further, the risk operation mode control module includes:
the first control module is used for controlling the power flow direction among the micro-grids;
and the second control module is used for controlling the load and the output of the power transmission line and the power station.
Further, the isolated network operation mode control module includes:
the third control module is used for correspondingly cutting off the load of the micro-grid under the condition that the unit faults in the micro-grid exist and the micro-grid exits operation so as to maintain power balance;
and the fourth control module is used for correspondingly reducing the output of the micro-grid to maintain the power balance under the condition that the line fault tripping load occurs in the micro-grid.
Further, the recovery grid-connected operation mode control module includes:
a fifth control module for reducing a voltage difference between each of the plurality of micro-grids and the main grid;
a sixth control module configured to adjust a frequency of each of the plurality of micro-grids such that the frequency of each micro-grid is lower than a frequency of the main grid;
and a seventh control module for adjusting the voltage of each of the plurality of micro-grids such that the phase of the voltage of the main grid leads the phase of the voltage of each micro-grid.
Further, in a case where the plurality of micro-grids includes a first micro-grid in communication with a main grid and a second micro-grid in communication with the first micro-grid, the first control module includes:
the first control unit is used for controlling the main power grid and the second micro power grid to respectively transmit power to the first micro power grid;
the second control unit is used for controlling the main power grid to transmit power to the first micro power grid, and the first micro power grid to transmit power to the second micro power grid;
a third control unit for controlling the first micro-grid to transmit power to the main grid and the second micro-grid, respectively;
and the fourth control unit is used for controlling the second micro-grid to transmit power to the first micro-grid, and the first micro-grid to transmit power to the main grid.
It should be noted that the number of the substrates,
in the risk operation mode, the plurality of micro-grids execute a risk operation control strategy and perform isolated network operation criteria so as to prepare for stably transitioning to the isolated network operation mode. The risk operation mode is an emergency mode which is entered in advance before extremely severe weather such as typhoons and the like comes, in order to prevent power failure caused by heavy wind and heavy rain. The micro-grid master controller in the risk operation mode monitors the operation state of each power transmission line, monitors the load level and the output level of each power station, operates the isolated grid criterion and the related stable control strategy, inputs the tripping outlet pressing plate, and prepares for stably transitioning to the isolated grid operation state.
Before the extreme weather comes, according to the weather early warning information and the risk early warning level, a dispatcher orders to put into a function outlet pressing plate, and sets an operation mode to be a 'risk operation mode' in a micro-grid master controller, and the system is switched to operate in the risk mode. On the basis of fully analyzing and researching the water and electricity output and load characteristics of the power grid during typhoon early warning, the application functions of power grid optimization scheduling, online safety early warning and the like under a risk mode are built by utilizing theory, a micro-grid master controller provides operation strategies and suggestions for operators, loads and outputs of partial lines and plant stations are controlled, and therefore stable operation of the power grid is guaranteed, and the power grid stably enters a grid-isolated operation mode after a tie line trips.
Under the isolated grid operation mode, the micro-grid master controller coordinates the small hydropower output and the micro-grid load through operating an isolated grid stability control strategy, cuts off part of the load, realizes source load balance, and ensures the stable operation of the micro-grid and the continuous blackness of important loads of the grid. In the isolated network operation mode, the grid structure and the load level are greatly different from the normal mode, and the system impedance and the short-circuit current are greatly different from the normal mode. According to the relay protection scheme in isolated network operation, after the micro-grid master controller is switched into an isolated network operation mode, the original relay protection device does not need to be modified, a new relay protection scheme is executed through the micro-grid master controller, and a relay protection function is provided for a line in isolated network operation.
After the plurality of micro-grids are controlled to be converted from the risk operation mode to the isolated grid operation mode, the plurality of micro-grids are controlled to be converted from the isolated grid operation mode to the recovery grid-connected operation mode under the condition that faults of the plurality of micro-grids are all eliminated. The reliability and stability of isolated network operation are inferior to those of grid-connected operation, and when the main power grid tie line is removed, the isolated network in operation should be arranged to be integrated into the main power grid as soon as possible.
In summary, the embodiment realizes the cyclic switching of the four operation modes, namely the grid-connected operation mode, the risk operation mode, the isolated grid operation mode and the recovery grid-connected operation mode, and ensures the stable switching of the micro-grid and improves the operation stability of the micro-grid due to the addition of the risk operation mode and the recovery grid-connected operation mode.
Example 2
A micro grid control method applied to the micro grid control system according to embodiment 1, the micro grid control method comprising:
monitoring the running state of the micro-grid and sending the running state to the micro-grid master controller;
and receiving a control instruction of the micro-grid master controller to control the micro-grid to operate in one of a grid-connected operation mode, a risk operation mode, a grid-isolated operation mode and a grid-connected operation mode recovery operation mode.
Compared with the prior art, the invention has the beneficial effects that:
the method monitors the running state of the micro-grid through the micro-grid controller, sends the running state to the micro-grid master controller, and receives a control instruction of the micro-grid master controller so as to control the micro-grid to run in one running mode of a grid-connected running mode, a risk running mode, a grid-isolated running mode and a grid-connected running mode; smooth switching of the micro-grid operation mode is achieved.
The micro-grid controller adaptively adjusts the discharge power of the user side according to the power consumption of the grid-connected side, the first critical power value and the second critical power value, wherein the discharge power of the user side comprises the discharge power of an energy storage system and the power generation power of a power generation system; and the discharge power of the user side in the micro-grid is adaptively regulated in real time, so that the power consumption of the grid-connected side is ensured to be in a planned demand range, and the power supply and demand balance of the user side is achieved.
The power generation system of the present invention includes: the photovoltaic power generation system and the wind power generation system can obtain stable output by utilizing the complementarity of wind energy and solar energy, and the system has higher stability and reliability; meanwhile, under the condition of ensuring the same power supply, the battery capacity of the energy storage system can be reduced. In addition, compared with diesel engine power generation, the wind energy and solar energy are utilized to generate power, so that the power generation cost can be reduced, and the environmental pollution is reduced. Moreover, the wind energy and the solar energy are rich in resources and have great development potential.
The above embodiments are merely illustrative of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention, and various modifications and improvements made by those skilled in the art to the technical solution of the present invention should fall within the scope of protection defined by the claims of the present invention without departing from the spirit of the design of the present invention.
Claims (9)
1. A microgrid control system, comprising: the micro-grid system comprises a micro-grid master controller and a plurality of micro-grids, wherein the micro-grids are connected through a power transmission line and a connecting line, and the micro-grid master controller is electrically connected with a micro-grid controller of each micro-grid in the micro-grids; the micro-grid controller is used for monitoring the running state of the micro-grid, sending the running state to the micro-grid master controller and receiving a control instruction of the micro-grid master controller so as to control the micro-grid to run in one running mode of a grid-connected running mode, a risk running mode, a grid-isolated running mode and a recovery grid-connected running mode;
the microgrid comprises: the system comprises a grid-connected end and a user end, wherein the grid-connected end is connected with a main power grid, the user end comprises an energy storage system and a power generation system, and the micro-power grid controller is connected with the energy storage system, the power generation system and the grid-connected end;
the micro-grid controller is used for acquiring the power consumption of the grid-connected end and the discharge power of the user end, acquiring a first critical power value of the power consumption exceeding the required amount of the grid-connected end and a second critical power value of the power inversion of the grid-connected end, and adaptively adjusting the discharge power of the user end according to the power consumption of the grid-connected end, the first critical power value and the second critical power value;
the discharging power of the user side comprises the discharging power of an energy storage system and the generating power of a generating system, and the generating system comprises: a photovoltaic power generation system and a wind power generation system;
the micro-grid is provided with a reactive compensation device,
in the grid-connected operation mode, when the micro-grid is required to output reactive power, the reactive power compensation device controls the energy storage system to output reactive power, and the calculation formula of the output reactive power of the energy storage system is as follows:
Qb=－λUm·ΔU
wherein: qb is reactive compensation capacity; lambda is a compensation coefficient; um is the micro-grid busbar voltage; ΔU is the voltage deviation.
2. The microgrid control system according to claim 1, wherein said energy storage system is a hybrid energy storage system comprising a power-type energy storage system and an energy-type energy storage system, wherein power variations in a short time scale are regulated by the power-type energy storage system and power variations in a long time scale are regulated by the energy-type energy storage system.
3. The microgrid control system according to claim 1, wherein said energy storage system comprises a plurality of energy storage units, wherein each of said energy storage unit outputs is distributed by a weighted distribution algorithm; the method comprises the following steps:
during charging, the output of each energy storage unit is distributed according to the percentage of the energy storage electric quantity consumed by each energy storage unit to the total energy storage electric quantity consumed;
and during discharging, distributing the output of each energy storage unit according to the percentage of the residual energy storage electric quantity of each energy storage unit to the total residual energy storage electric quantity.
4. The microgrid control system according to claim 1, wherein said microgrid master controller comprises:
the risk operation mode control module is used for controlling the power flow direction among the micro-grids and controlling the load and the output of the transmission line and the power station;
the isolated network operation mode control module is used for controlling the plurality of micro-grids to be converted from a risk operation mode to an isolated network operation mode under the condition that one or more micro-grids in the plurality of micro-grids fail;
the grid-connected recovery operation mode control module is used for controlling the micro-grids to be converted from the isolated grid operation mode to the grid-connected recovery operation mode under the condition that the faults of the micro-grids are all eliminated;
and the grid-connected operation mode control module is used for controlling the plurality of micro-grids to be converted into a grid-connected operation mode from the recovery grid-connected operation mode.
5. The microgrid control system according to claim 4, wherein said isolated network operation mode comprises:
under the condition that the unit fault exits from operation in the micro-grid, correspondingly cutting off the load of the micro-grid so as to maintain the power balance;
in the event of a line fault trip load in the microgrid, the output of the microgrid is correspondingly reduced to maintain power balance.
6. The microgrid control system according to claim 4, wherein said restoring a grid-connected mode of operation comprises:
reducing a voltage difference between each of the plurality of micro-grids and the main grid;
adjusting a frequency of each of the plurality of micro-grids such that the frequency of each micro-grid is lower than a frequency of the main grid;
the voltage of each of the plurality of micro-grids is adjusted such that the phase of the voltage of the main grid leads the phase of the voltage of each micro-grid.
7. The microgrid control system according to claim 1, characterized in that said reactive compensation means comprises: the device comprises a detection module, a control operation module and a compensation output module, wherein the control operation module is connected with the detection module and the compensation output module.
8. A microgrid control method, characterized in that the microgrid control method is applied to a microgrid control system according to any one of claims 1 to 7, the microgrid control method comprising:
monitoring the running state of the micro-grid and sending the running state to the micro-grid master controller;
and receiving a control instruction of the micro-grid master controller to control the micro-grid to operate in one of a grid-connected operation mode, a risk operation mode, a grid-isolated operation mode and a grid-connected operation mode recovery operation mode.
9. The microgrid control method according to claim 8, characterized in that said microgrid control method further comprises:
collecting the power consumption of the grid-connected terminal and the discharge power of the user terminal, and obtaining a first critical power value of the power consumption exceeding the required quantity of the grid-connected terminal and a second critical power value of the power inversion of the grid-connected terminal;
and adaptively adjusting the discharge power of the user side according to the power consumption of the grid-connected side, the first critical power value and the second critical power value.
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