CN114629174A - Microgrid operation control method and device and microgrid - Google Patents

Microgrid operation control method and device and microgrid Download PDF

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Publication number
CN114629174A
CN114629174A CN202210423088.2A CN202210423088A CN114629174A CN 114629174 A CN114629174 A CN 114629174A CN 202210423088 A CN202210423088 A CN 202210423088A CN 114629174 A CN114629174 A CN 114629174A
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energy storage
grid
microgrid
voltage
power
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Inventor
黄杨珏
姚瑶
宋萌
吕鸿
汪进锋
夏亚君
陈鹏
朱远哲
金杨
朱家华
刘文晖
谢志文
尹海庆
王伟
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Guangdong Power Grid Co Ltd
Electric Power Research Institute of Guangdong Power Grid Co Ltd
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Guangdong Power Grid Co Ltd
Electric Power Research Institute of Guangdong Power Grid Co Ltd
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Priority to CN202210423088.2A priority Critical patent/CN114629174A/en
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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
    • 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
    • H02J3/007—Arrangements for selectively connecting the load or loads to one or several among a plurality of power lines or power sources
    • H02J3/0075—Arrangements for selectively connecting the load or loads to one or several among a plurality of power lines or power sources for providing alternative feeding paths between load and source according to economic or energy efficiency considerations, e.g. economic dispatch
    • 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
    • H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
    • 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
    • H02J3/28—Arrangements for balancing of the load in a network by storage of energy
    • H02J3/32—Arrangements for balancing of the load in a network by storage of energy using batteries with converting means
    • 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
    • H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
    • H02J3/466—Scheduling the operation of the generators, e.g. connecting or disconnecting generators to meet a given demand
    • 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
    • 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

Abstract

The application discloses a micro-grid operation control method, a control device and a micro-grid, wherein the operation control method comprises the following steps: determining the running state of a grid-connected point of the microgrid and the voltage value of a busbar of the microgrid; based on a peak-valley electricity price mechanism, establishing management strategies for the running states of different microgrid grid-connected points, and establishing corresponding control strategies according to different microgrid bus voltages; and controlling the operation of the microgrid by using a management strategy or a control strategy. The microgrid operation control method is based on a composite superconducting energy storage-current limiting microgrid, and a regulation and control strategy of a photovoltaic storage system is established by combining peak and valley electricity prices, so that the electricity consumption of a large power grid and the dependence of a power utilization area on the power grid are reduced, the operation cost of the microgrid is reduced, and the power supply quality, the power supply reliability and stability are improved.

Description

Microgrid operation control method and device and microgrid
Technical Field
The application relates to the technical field of micro-grids, in particular to a micro-grid operation control method and system.
Background
The existing light storage micro grid system balances the voltage of a direct current bus by adding a super capacitor at the direct current side, so that the reactive current output of a photovoltaic inverter is ensured, and the light storage micro grid system meets the requirement of low voltage ride through. However, the output current of the photovoltaic inverter is increased due to the imbalance of power during the voltage sag, and may exceed the output current limit of the inverter itself, so that the inverter triggers the overcurrent protection to cause the light storage microgrid system to be disconnected. In addition, the existing light storage micro-grid system has too strong dependence on a power grid, and the random charge and discharge characteristics of a system energy storage device are too large, so that the flexibility, safety and economy of the micro-grid cannot be embodied. Meanwhile, the anti-interference capability of the optical storage micro-grid system is weak when the optical storage micro-grid system operates in an isolated grid, so that the requirements of users on high power supply quality and high energy efficiency cannot be met.
Disclosure of Invention
The application aims to provide a micro-grid operation control method and system to reduce the operation cost of an optical storage micro-grid, enhance the low-voltage ride through capability of an optical storage micro-grid system and improve the power supply stability and the power supply quality.
In order to achieve the above object, the present application provides a microgrid operation control method, including:
determining the running state of a grid-connected point of the microgrid and the voltage value of a busbar of the microgrid;
based on a peak-valley electricity price mechanism, establishing management strategies for the running states of different microgrid grid-connected points, and establishing corresponding control strategies according to different microgrid bus voltages;
and controlling the operation of the microgrid by using a management strategy or a control strategy.
Further, the making of a management strategy for the operation states of different microgrid grid-connected points based on a peak-valley electricity price mechanism includes:
when the grid-connected point is in a normal operation state, calculating the output power and the load power of a photovoltaic system in the microgrid;
when the output power is greater than the load power and the electric quantity supplied by the photovoltaic system is surplus, charging the energy storage battery until the energy storage battery is full, and transmitting the surplus electric energy to a large power grid;
when the output power is smaller than the load power and the electricity price is in the peak time period, determining an object for supplying power to the load according to the charge state of the energy storage battery;
when the output power is smaller than the load power and the electricity price is in the valley period, the photovoltaic system supplies power to the load, the large power grid provides the load power shortage, and the large power grid is used for charging the energy storage battery until the energy storage battery is fully charged;
when the output power is smaller than the load power and the electricity price is in a non-peak value or non-valley value time period, the energy storage battery is not charged and discharged, and the photovoltaic system and the commercial power supply jointly supply power for the load.
Further, when the output power is smaller than the load power and the electricity price is in the peak time period, determining an object for supplying power to the load according to the state of charge of the energy storage battery, including:
if the state of charge of the energy storage battery is higher than the maximum value of the state of charge, the energy storage battery is used for supplying power to the load;
if the state of charge of the energy storage battery is between the minimum value and the maximum value of the state of charge, and the provided electric energy is less than the load shortage power, purchasing the required electric quantity from the commercial power;
and if the state of charge of the energy storage battery is smaller than the minimum state of charge, stopping discharging the energy storage battery, and supplying power to the load by the photovoltaic system and the large power grid together.
Further, based on the peak-valley electricity price mechanism, a management strategy is formulated for the operation states of different microgrid grid-connected points, and the method further comprises the following steps:
when a grid-connected point has a fault and the current of a power grid is greater than the action current of a current limiter, the micro-grid meets the requirement of low voltage ride through and keeps grid-connected operation through the regulation of a superconducting current limiter;
when the grid-connected point has a fault and the current of the power grid is smaller than the action current of the current limiter, the photovoltaic inverter is used for adjusting to enable the micro-grid to meet the requirement of low voltage ride through and keep grid-connected operation.
Further, based on the peak-valley electricity price mechanism, a management strategy is formulated for the operation states of different microgrid grid-connected points, and the method further comprises the following steps:
and when the grid-connected point has a fault and the micro-grid still does not meet the low-voltage ride-through requirement after adjustment, issuing a control instruction to enable the micro-grid to run off-grid.
Further, the formulating of corresponding control strategies according to different microgrid bus voltages includes:
when the voltage of the microgrid bus is in a normal operation state, the composite superconducting energy storage device in the microgrid does not act;
when the voltage of the microgrid bus is disturbed and the composite superconducting energy storage device meets the starting condition, determining the action of the energy storage battery or the composite superconducting energy storage device according to the voltage and the current of the energy storage battery and the voltage and the current of the composite superconducting energy storage device;
and when the voltage of the microgrid bus is disturbed and the composite superconducting energy storage device does not meet the starting condition, controlling the action of the voltage regulator.
Further, when the voltage of the microgrid bus is disturbed and the composite superconducting energy storage device meets the starting condition, determining the action of the energy storage battery or the composite superconducting energy storage device according to the voltage and the current of the energy storage battery and the voltage and the current of the composite superconducting energy storage device, including:
when the current of the composite superconducting energy storage device is smaller than the maximum current limit value of the composite superconducting energy storage device and the voltage of the microgrid bus is larger than the voltage of the composite superconducting energy storage device, controlling the composite superconducting energy storage device to charge;
when the voltage of the composite superconducting energy storage device is greater than the maximum voltage limit value of the composite superconducting energy storage device and the voltage of a microgrid bus is greater than the charging starting voltage of the energy storage battery, the composite superconducting energy storage device is controlled to absorb redundant electric energy of a load;
when the voltage of the microgrid bus is smaller than the maximum voltage limit value of the composite superconducting energy storage device and the current of the composite superconducting energy storage device is larger than the minimum current limit value of the composite superconducting energy storage device, controlling the composite superconducting energy storage device to enter a discharging mode;
and when the voltage of the composite superconducting energy storage device is smaller than the minimum voltage limit value of the composite superconducting energy storage device and the charging starting voltage of the energy storage battery is larger than the minimum voltage limit value of the composite superconducting energy storage device, compensating the energy storage battery.
The application also provides a little electric wire netting operation control device, includes:
the parameter acquisition module is used for determining the running state of a grid-connected point of the micro-grid and the voltage value of a bus of the micro-grid;
the strategy determining module is used for making a management strategy for the running states of different microgrid grid-connected points based on a peak-valley electricity price mechanism and making a corresponding control strategy according to different microgrid bus voltages;
and the control module is used for controlling the operation of the microgrid by utilizing a management strategy or a control strategy.
Further, the policy determining module includes a normal operation control unit of the grid-connected point, and is configured to:
when the grid-connected point is in a normal operation state, calculating the output power and the load power of a photovoltaic system in the microgrid;
when the output power is greater than the load power and the electric quantity supplied by the photovoltaic system is residual, the energy storage battery is charged, and the residual electric energy is transmitted to a large power grid until the energy storage battery is fully charged;
when the output power is smaller than the load power and the electricity price is in the peak time period, determining an object for supplying power to the load according to the charge state of the energy storage battery;
when the output power is smaller than the load power and the electricity price is in a valley period, the photovoltaic system supplies power to the load, the large power grid provides the load power shortage, and the large power grid is used for charging the energy storage battery until the energy storage battery is fully charged;
when the output power is smaller than the load power and the electricity price is in a non-peak value or non-valley value time period, the energy storage battery is not charged and discharged, and the photovoltaic system and the commercial power supply jointly supply power for the load.
Further, the normal operation control unit of the grid-connected point is further configured to:
if the state of charge of the energy storage battery is higher than the maximum value of the state of charge, the energy storage battery is used for supplying power to the load;
if the state of charge of the energy storage battery is between the minimum value and the maximum value of the state of charge, and the provided electric energy is less than the load shortage power, purchasing the required electric quantity from the commercial power;
and if the state of charge of the energy storage battery is smaller than the minimum state of charge, stopping discharging the energy storage battery, and supplying power to the load by the photovoltaic system and the large power grid together.
Further, the policy determination module further includes:
the grid-connected point fault first control unit is used for enabling the micro-grid to meet the low-voltage ride-through requirement and keep grid-connected operation through the regulation of the superconducting current limiter when a grid-connected point is in fault and the current of the power grid is larger than the action current of the current limiter;
and the grid-connected point fault second control unit is used for enabling the micro-grid to meet the low-voltage ride-through requirement and keep grid-connected operation through the regulation of the photovoltaic inverter when the grid-connected point is in fault and the grid current is smaller than the action current of the current limiter.
Further, the policy determining module further includes a third control unit for grid-connected point fault, configured to:
and when the grid-connected point has a fault and the micro-grid still does not meet the low-voltage ride-through requirement after adjustment, issuing a control instruction to enable the micro-grid to run off-grid.
Further, the policy determination module further includes:
the bus voltage normal control unit is used for enabling the composite superconducting energy storage device in the microgrid not to act when the bus voltage of the microgrid is in a normal operation state;
the first control unit is used for determining the action of the energy storage battery or the composite superconducting energy storage device according to the voltage and the current of the energy storage battery and the voltage and the current of the composite superconducting energy storage device when the voltage of the microgrid bus is disturbed and the composite superconducting energy storage device meets the starting condition;
and the second control unit for controlling the action of the voltage regulator when the voltage of the microgrid bus is disturbed and the composite superconducting energy storage device does not meet the starting condition.
Further, the first control unit for abnormal bus voltage is further configured to:
when the voltage of the composite superconducting energy storage device is greater than the maximum voltage limit value of the composite superconducting energy storage device and the voltage of the microgrid bus is greater than the charging starting voltage of the energy storage battery, controlling the composite superconducting energy storage device to absorb redundant electric energy of the load;
when the voltage of the microgrid bus is smaller than the maximum voltage limit value of the composite superconducting energy storage device and the current of the composite superconducting energy storage device is larger than the minimum current limit value of the composite superconducting energy storage device, controlling the composite superconducting energy storage device to enter a discharging mode;
and when the voltage of the composite superconducting energy storage device is smaller than the minimum voltage limit value of the composite superconducting energy storage device and the charging starting voltage of the energy storage battery is larger than the minimum voltage limit value of the composite superconducting energy storage device, compensating the energy storage battery.
The present application further provides a microgrid, comprising:
the system comprises a superconducting current limiter, a photovoltaic system, a photovoltaic inverter, a three-winding transformer, a composite superconducting energy storage device, a rectifier and a microgrid bus;
each load is connected to the microgrid bus through the superconducting current limiter;
the photovoltaic system is connected to a pc line through the photovoltaic inverter, the three-winding transformer and the superconducting current limiter in sequence;
and the composite superconducting energy storage device is connected to the microgrid bus through the rectifier.
Compared with the prior art, the beneficial effects of this application lie in:
the micro-grid operation control method is based on the composite superconducting energy storage-current limiting micro-grid-connected operation, the regulation and control strategy of the light storage system is established by combining the peak-valley electricity price, the electricity consumption of a large power grid and the dependence of an electricity utilization area on the power grid are reduced, solar photovoltaic resources are fully utilized, a peak-valley electricity price mechanism can be utilized, peak-valley arbitrage is realized, the operation cost of the light storage micro-grid is reduced, the short-circuit current is limited through the superconducting current limiter, the drop amplitude of the grid-connected point voltage is reduced, and therefore the low-voltage ride through capability of the light storage micro-grid system is improved. The composite superconducting energy storage-current limiting device improves the electric energy quality of a microgrid, improves the power supply stability, can ensure that the microgrid in regions is integrated and operates independently when the power supply is insufficient or fails, improves the reliability of power supply in various regions, realizes barrier-free coordinated operation of new energy and a large power grid, improves the intelligentization level of a power supply system, enhances the disaster resistance, and provides technical support for improving the service quality of power utilization regions.
Drawings
In order to more clearly illustrate the technical solutions of the present application, the drawings required to be used in the embodiments will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic system structure diagram of a microgrid provided in an embodiment of the present application;
fig. 2 is a schematic diagram illustrating a principle that a photovoltaic grid-connected system provided in an embodiment of the present application requires a low voltage ride through capability;
fig. 3 is a schematic flowchart of a microgrid operation control method according to an embodiment of the present application;
fig. 4 is a flowchart illustrating steps of a microgrid operation control method according to an embodiment of the present application;
fig. 5 is a flowchart illustrating steps of a microgrid operation control method according to another embodiment of the present application;
fig. 6 is a schematic structural diagram of a microgrid operation control device according to an embodiment of the present application;
FIG. 7 is a sub-block diagram of the policy determination module 02 of FIG. 6.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments in the present application without making any creative effort belong to the protection scope of the present application.
It should be understood that the step numbers used herein are for convenience of description only and are not intended as limitations on the order in which the steps are performed.
It is to be understood that the terminology used in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in the specification of the present application and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
The terms "comprises" and "comprising" indicate the presence of the described features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
The term "and/or" refers to any and all possible combinations of one or more of the associated listed items and includes such combinations.
It should be noted that after the micro-grid concept is proposed, the micro-grid concept is widely concerned and demonstrated in all parts of the world, but the definition and research focus of the micro-grid are different, for example, the distributed light storage micro-grid is considered to be one of effective ways for guaranteeing the sustainable development of world energy in China. Therefore, the development of distributed energy is also bound to be a great importance, and the development of distributed power is one of the directions of energy revolution. The development of the distributed power supply mainly based on photovoltaic needs to be based on the principle of 'making local conditions and scientific utilization', and the power supply is mainly installed and consumed nearby at a user side, so that the power utilization efficiency is improved, and the power transmission loss and cost are reduced.
The light-storage integrated system generally comprises a photovoltaic module and an energy storage module, and is matched with a power grid to complete power supply. The system is used as a main power supply source, and a power grid is used as a backup power supply. However, as the permeability of the photovoltaic system is continuously improved, the safe and stable operation of the power system requires that the microgrid system should have a Low Voltage Ride Through (LVRT) capability, that is, during a grid fault, the photovoltaic system should keep uninterrupted grid-connected operation for a certain time. In addition, in a micro-grid system, the existence of the energy storage battery can also complete auxiliary functions of smoothing photovoltaic power generation fluctuation, peak-load and frequency modulation and the like, and the reliability and stability of photovoltaic energy access are improved. Meanwhile, in order to achieve harmonious power supply of the power grid and the photovoltaic energy storage equipment and avoid energy waste, a corresponding power supply control strategy must be formulated so as to achieve the following aims:
1) when the grid-connected point voltage drops for a short time due to grid faults or voltage disturbance, the micro-grid system can not be separated from the grid, even can transmit certain reactive power to the grid to support the grid-connected point voltage until the grid voltage returns to normal, so that the low voltage ride-through time is realized, and the low voltage ride-through requirement is met.
2) When the photovoltaic power generation is larger than the power load, the photovoltaic power generation supplies power to the load, and redundant electric quantity is stored in the energy storage battery. Even when the energy storage battery is fully charged, the surplus electric quantity can be transmitted to the power grid.
3) When the photovoltaic power generation is smaller than the electric load, the load is supplied with power by the energy storage battery and the photovoltaic.
4) When the photovoltaic power generation is equal to the electric load, the photovoltaic power generation supplies power to the load, the energy storage battery is not charged or discharged, and the energy is kept unchanged.
5) When the photovoltaic power generation is smaller than the power load, if the electric quantity of the energy storage battery is insufficient, the power supply is switched to the power grid for power supply.
However, when a photovoltaic power generation system operates in an isolated grid mode due to planned or unplanned islanding, and when a certain branch of a local load fails, the anti-interference capability of a micro-grid is low, the bus voltage is difficult to maintain stable, voltage fluctuation is caused, and the following influences are generated on power utilization equipment: 1) the aging of the insulating layer of the electric equipment is accelerated, and the service life of the electric equipment is shortened; 2) the loss of the electric equipment is increased, and the efficiency of the power grid is reduced; 3) the electric equipment can not work normally, and the product and service quality are seriously influenced; 4) misoperation of the electric equipment can be caused, and production accidents are caused; 5) the safety of personnel and electric equipment can be endangered due to serious overvoltage faults. The main reason is that the conventional optical storage microgrid balances the voltage of a direct current bus by adding a super capacitor on a direct current side, so that the reactive current output of a photovoltaic inverter is ensured, and the optical storage microgrid grid-connected system meets the requirement of low-voltage ride-through, but the output current of the photovoltaic inverter is increased due to unbalanced power during voltage sag and possibly exceeds the output current limit of the inverter, so that the inverter can cause the optical storage microgrid system to be disconnected due to triggering of overcurrent protection.
In view of the above problems, an embodiment of the present application first provides a system structure of a microgrid, as shown in fig. 1. Wherein, this microgrid includes:
the system comprises a superconducting current limiter, a photovoltaic system, a photovoltaic inverter, a three-winding transformer, a composite superconducting energy storage device, a rectifier and a microgrid bus;
each load is connected to the microgrid bus through the superconducting current limiter;
the photovoltaic system is connected to a pc circuit through the photovoltaic inverter, the three-winding transformer and the superconducting current limiter in sequence;
and the composite superconducting energy storage device is connected to the microgrid bus through the rectifier.
It is to be explained that the requirement of low voltage ride through of the photovoltaic grid-connected system is met according to GB/T19964 and 2012 "specification of photovoltaic power station access power system". As shown in fig. 2, when the grid-connected point voltage is above curve 1, the pv grid-connected system should be able to keep grid-connected operation, and when the grid-connected point voltage is below curve 1, the pv grid-connected system is allowed to disconnect. The voltage drop of the grid-connected point is allowed to be 0V within 0-150ms, and within 2000ms after the fault occurs, the voltage of the grid-connected point needs to be recovered to be more than 90% of the voltage before the voltage drop. Under the condition of neglecting the loss of the photovoltaic grid-connected inverter, the vector control principle based on the grid voltage orientation comprises the following steps:
Figure BDA0003608743960000091
in the formula of UdcIs a DC side bus voltage, IdcFor photovoltaic cell output current usdIs the d-axis component, i, of the grid voltagedOutputting current for the inverter.
From the above equation (1), when the grid voltage remains unchanged and the loss of the grid-connected inverter itself is not considered, the dc side voltage U thereof is obtaineddcAnd an output current IdcIs in direct proportion. Because solar energy has the defects of gap, fluctuation and instability, an electric energy storage device with high sensitivity, quick response and strong compensation capacity is required to be configured to obtain high-quality, high-efficiency, stable, safe and reliable electric energy supply. Therefore, in this embodiment, a Superconducting Magnetic Energy Storage (SMES) system with a fast response speed and a high power density is used to replace a conventional Battery Energy Storage (BES) system with a slow response speed. In this embodiment, the composite superconducting energy storage device is specifically described. A superconducting energy storage system is selected for compensation in the early stage of load voltage failure; however, superconducting magnetic energy storage has a limited capacity, and thus is compensated by a battery energy storage system when the superconducting energy storage system cannot meet the energy requirements of the load system.
As shown in fig. 1, in the case that no superconducting current limiter is installed at a grid-connected point of a photovoltaic grid-connected system, when a voltage drop is caused by a grid fault, usdDecrease, in the condition of power balance idWill be increased, and usdThe larger the amplitude of the fall, idThe larger the value of (c). The inverter has a certain current limiting function and is usually set to be 1.1INWhen i isd＞1.1INThe output power of the inverter will decrease. The remaining power will be at the dc side capacitance C of the inverterdcResulting in an increase in the dc side bus voltage of the inverter. When the voltage rises to a certain value, the direct-current side overvoltage protection is triggered, so that the photovoltaic grid-connected system is disconnected. Meanwhile, the output current of the photovoltaic inverter is increased due to the unbalance of power during voltage sag, and may exceed the output current limit of the inverter, so that the inverter is disconnected due to triggering of overcurrent protection. The large-scale off-grid of the photovoltaic grid-connected system is bound toThe power of the system is greatly lost, the oscillation of the power grid is possibly aggravated, and the difficulty in recovering the voltage of the system is increased. Meanwhile, the grid disconnection of adjacent photovoltaic grid-connected systems can be caused, and a large-range power failure accident can be caused.
In the embodiment, when the superconducting current limiter is installed at the grid-connected point of the photovoltaic grid-connected system and the grid has a short-circuit fault, the grid voltage u is generatedsdDecrease idUp to an operating current I greater than that of the current limiterdsWhen the current limiter is "high impedance" response is suppressed, thus ensuring idMaintained at 1.1INWithin the range of (1), the output power of the inverter is kept stable, and the photovoltaic power generation system meets the requirement of low voltage ride through. And if the voltage of the grid-connected point bus without being cut off is lower than 0.9PU after 2000ms, the management center sends an instruction to control the off-grid operation of the optical storage micro-grid system.
Further, to help understanding, the present embodiment also explains the working principle of the Battery Energy Storage system, and the Battery Energy Storage system (BES) is an Energy Storage device that stores Energy in the form of electric Energy and can realize interconversion between chemical Energy and electric Energy. According to the characteristics of the energy storage battery, the following relationship exists between the charge and discharge power and the residual capacity of the storage battery:
in a charging state:
E(t)＝E(t-1)+ΔT·Pcharging device(t)ηCharging (CN) (2)
In a discharge state:
Figure BDA0003608743960000111
the state of charge of the storage battery is as follows:
Figure BDA0003608743960000112
to prevent overcharge and overdischarge of the energy storage battery, the state of charge needs to satisfy the following conditions:
SOCmin≤SOC≤SOCmax(5)
in the formula, E (t) is the total energy of the energy storage battery at the time t; pCharging device(t)、PPut(t) is the battery charge and discharge power at time t, respectively, and the charge power and the discharge power of the energy storage battery are specified to be positive and negative. EtaCharging device、ηPutRespectively the charge and discharge efficiency of the energy storage battery; the delta T is the charge-discharge time period of the storage battery; SOCmin and SOCmax are respectively the SOC upper and lower limit values in the charging and discharging process of the storage battery; qcCapacity of storage battery, IbatIs the charging current.
According to a peak-valley electrovalence mechanism, the energy storage battery can be used as a power supply to provide power in the optical storage micro-grid system, and can also be used as a load to absorb power, so that the effects of peak clipping and valley filling are achieved. Assuming that the exchange power between the power grid and the light storage micro-grid system is P, if the load and the light storage system use the electric energy of the power grid, P is more than 0, namely the power grid sells electricity to the light storage micro-grid system; if the light storage micro-grid system provides electric energy for the power grid, P is less than 0, and the light storage micro-grid sells electricity to the power grid.
According to the power balance relationship between the light storage micro-grid system and the large-grid system, the method comprises the following steps:
when the P is greater than 0, the P is,
Pload(t)＝Ppv(t)+Pbat(t)+P(t) (6)
when the P is less than 0, the content of the compound,
Pload(t)＝Ppv(t)+Pbat(t)-P(t) (7)
in the formula, Pload(t) load Power at time t, Ppv(t) is the photovoltaic output power, wherein P is the discharge of the energy storage batterybatWhen the battery is charged, PbatIs less than 0; when P isbatWhen the battery value is 0, the battery is not charged and discharged.
And the charging and discharging of the energy storage battery are realized by controlling the energy storage converter according to a power instruction issued by the energy management center, and the battery is charged or discharged. Therefore, the management strategy of the light storage micro-grid system needs to be made by combining the output and load characteristics of the photovoltaic system, the charge state of the storage battery and the peak-valley electricity price mechanism.
In the embodiment, the superconducting current limiter is connected into the microgrid to limit the short-circuit current and reduce the drop amplitude of the grid-connected point voltage, so that the low-voltage ride through capability of the light storage microgrid system is improved.
Specifically, referring to fig. 3, an embodiment of the present application provides a method for controlling operation of a micro grid. As shown in fig. 3, the microgrid operation control method includes steps S10 to S30. The method comprises the following steps:
s10, determining the running state of the grid-connected point of the micro-grid and the voltage value of the bus of the micro-grid;
s20, based on a peak-valley electricity price mechanism, making management strategies for the operation states of different microgrid grid-connected points, and making corresponding control strategies according to different microgrid bus voltages;
and S30, controlling the operation of the microgrid by using a management strategy or a control strategy.
In the embodiment, the operation state of the grid-connected point of the microgrid and the voltage value of the busbar of the microgrid are determined, then a corresponding management strategy and a control strategy are formulated by combining a peak-valley electricity price mechanism, and finally the operation of the microgrid is controlled.
Referring to fig. 4, specifically, the method for establishing a management policy for the operation states of different microgrid grid-connected points includes the following steps:
1) when the grid-connected point is in a normal operation state, calculating the output power and the load power of a photovoltaic system in the microgrid;
1.1) output power PpvGreater than the load power PloadAnd when the electric quantity supplied by the photovoltaic system is residual, the energy storage battery is charged until the energy storage battery is full, namely the SOC is reachedmaxThen, the redundant electric energy is transmitted to a large power grid;
1.2) output power PpvLess than load power PloadWhen the electricity price is in the peak time period, determining an object for supplying power to the load according to the charge state of the energy storage battery;
1.3) output power PpvLess than load power PloadWhen the electricity price is in the valley time period, the photovoltaic system supplies power to the load, the large power grid provides the load power shortage, and the large power grid is utilizedThe network charges the energy storage battery until the energy storage battery is full;
1.4) output power PpvLess than load power PloadAnd when the electricity price is in a non-peak value or non-valley value time period, the energy storage battery is not charged and discharged, and the photovoltaic system and the commercial power supply jointly supply power for the load.
Further, step 1.2) specifically includes:
1.2.1) if the state of charge SOC of the energy storage battery is higher than the maximum SOC valuemaxThen the energy storage battery is used for supplying power to the load;
1.2.2) if the SOC of the energy storage battery is between the minimum SOC and the maximum SOC, the SOC belongs tomin，SOCmax]The range, and the electric energy that can provide is less than the power of the load shortage, purchase the necessary electric quantity from the commercial power;
1.2.3) if the state of charge of the energy storage battery is less than the minimum state of charge SOCminAnd the energy storage battery stops discharging, and the photovoltaic system and the large power grid jointly supply power to the load.
In a certain embodiment, based on a peak-valley electricity price mechanism, a management strategy is formulated for the operation states of different microgrid interconnection points, and the method further comprises the following steps:
2) when the grid-connected point is faulty and the grid current is greater than the action current of the current limiter, i.e. Id＞IdsWhen the low-voltage-ride through is required, the micro-grid is adjusted by the superconducting current limiter to be in grid-connected operation;
3) when the grid-connected point is faulty and the grid current is less than the action current of the current limiter, i.e. Id＜IdsAnd meanwhile, the micro-grid is regulated by the photovoltaic inverter to meet the requirement of low voltage ride through and keep grid-connected operation.
It should be noted that after the fault is removed, the microgrid system is still in a grid-connected operation state, and at this time, the microgrid system should follow a management control strategy in a normal operation state.
Further, based on a peak-valley electricity price mechanism, a management strategy is formulated for the operation states of different microgrid grid-connected points, and the method further comprises the following steps:
4) when the grid-connected point has a fault and the micro-grid still does not meet the low-voltage ride-through requirement after adjustment, a control instruction is issued to enable the micro-grid to run off-grid, and at the moment, the micro-grid system follows an isolated grid running management control strategy.
Referring to fig. 5, in an embodiment, the setting of the corresponding control strategy according to different voltages of the microgrid buses includes:
5) when the voltage of the microgrid bus is in a normal operation state, the composite superconducting energy storage device in the microgrid does not act;
6) when the voltage of the microgrid bus is disturbed and the composite superconducting energy storage device meets the starting condition, determining the action of the energy storage battery or the composite superconducting energy storage device according to the voltage and the current of the energy storage battery and the voltage and the current of the composite superconducting energy storage device;
7) and when the voltage of the microgrid bus is disturbed and the composite superconducting energy storage device does not meet the starting condition, controlling the action of the voltage regulator.
Further, the step 6) specifically comprises:
6.1) when the current of the composite superconducting energy storage device is smaller than the maximum current limit value of the composite superconducting energy storage device and the voltage of a microgrid bus is larger than the voltage of the composite superconducting energy storage device, controlling the composite superconducting energy storage device to charge;
6.2) when the voltage of the composite superconducting energy storage device is greater than the maximum voltage limit value of the composite superconducting energy storage device and the voltage of the microgrid bus is greater than the charging starting voltage of the energy storage battery, controlling the composite superconducting energy storage device to absorb redundant electric energy of the load;
6.3) when the voltage of the microgrid bus is smaller than the maximum voltage limit value of the composite superconducting energy storage device and the current of the composite superconducting energy storage device is larger than the minimum current limit value of the composite superconducting energy storage device, controlling the composite superconducting energy storage device to enter a discharging mode;
and 6.4) when the voltage of the composite superconducting energy storage device is smaller than the minimum voltage limit value of the composite superconducting energy storage device and the charging starting voltage of the energy storage battery is larger than the minimum voltage limit value of the composite superconducting energy storage device, compensating the energy storage battery.
It should be noted that, in this embodiment, when the micro-grid bus voltage U is in the normal operation state, that is, U is in the normal operation statemin<U<UmaxAnd the composite superconducting energy storage system does not act. When the light storage micro-grid operates in an isolated network, due to weak anti-interference capability of the micro-grid, the large-load switching can cause the fluctuation of the bus voltage of the micro-grid, and if U is more than UmaxThe control system first determines whether the current of the superconducting energy storage coil satisfies the condition (I)SMES<Imax) And the bus voltage U is greater than the charging voltage U of the superconducting energy storage systemSMESThe system instantly starts a charging mode of the superconducting energy storage system, and the bus voltage U is maintained in a normal range to ensure the voltage stability of other loads; when the voltage U of the superconducting energy storage systemSMESGreater than a limit value UmaxAnd the bus voltage U is greater than the charging starting voltage U of the storage batteryBESAnd in time, the storage battery system absorbs redundant electric energy of the load and maintains the stability of the bus voltage. If U is less than UmaxThe control system first determines whether the current of the superconducting magnetic energy storage coil satisfies the condition (I)SMES＞Imin) The system instantly starts a discharging electric mode of the superconducting energy storage system, and the bus voltage U is maintained in a normal range to ensure the voltage stability of other loads; when the voltage U of the superconducting energy storage systemSMESLess than the limit value UminAnd the discharge voltage U of the storage batteryBESGreater than discharge voltage UminWhen the bus is in shortage, the shortage voltage of the bus is compensated by the storage battery. If the voltage of the microgrid bus is disturbed and the composite superconducting energy storage system does not meet the starting condition, the problem is solved by other measures (a voltage regulator and the like).
A superconducting current limiter is a device used in series in a line, and an important operating parameter of the current limiter is the impedance of the device during normal transmission of the line, sometimes referred to as the steady-state impedance. The smaller the value, the less negative the current limiter has on the transmission line (e.g. equipment voltage drop, transmission losses). When the circuit normally transmits power, the current limiter is in a superconducting state, the impedance is zero, no power transmission loss exists, and the power transmission efficiency is not influenced.
As shown in figure 1, n branches are arranged at the position of a composite superconducting energy storage-current limiting microgrid bus and operate in parallel, and the current limiting microgrid is not installedWhen a short-circuit fault occurs in a branch of the device (assumed as a local load 1), the load current ifWill increase sharply, the load voltage VfIt drops sharply to 0V, at which point the other loads on the bus will generate a reverse surge current at the moment of the fault, causing voltage fluctuations. When the branch circuit with the current limiter is in short-circuit fault, the current i of the power supply busfUp to an operating current I greater than that of the current limiterdsIn the process, because the current limiter responds in a high impedance way to be restrained, the load current and the voltage of the non-fault parallel branch circuit are basically kept unchanged, and meanwhile, the response of the superconducting energy storage device further keeps the stability of the bus voltage, so that the stable operation of the non-fault branch circuit is ensured. It is worth noting that: after the local load 1 has a short-circuit fault, the superconducting current limiter presents high impedance to limit the short-circuit current because the short-circuit fault current is increased to trigger the superconducting current limiting action, and a relay protection device in the protection system cannot be damaged by the short-circuit current. Meanwhile, the voltage (the steady-state operation voltage is 0V) of the superconducting current limiter when the loss time is out can be coordinated with the relay protection, so that the failure and misoperation can be avoided when the protection is triggered, and meanwhile, a fault line can be timely and correctly cut off.
According to the microgrid operation control method provided by the embodiment, the configuration capacities of a photovoltaic system and an energy storage system are determined according to the load characteristics of a light storage microgrid system and peak-valley electricity price information, a light storage power coordination control strategy based on peak-valley electricity price difference is provided, the maximum economic benefit is expected to be obtained, the operation cost of the light storage microgrid is reduced, the electric energy quality of the microgrid is improved, the power supply stability is improved, the microgrid in regions can be ensured to be integrated and operate independently when the power supply is insufficient or fails, the reliability of power supply in various regions is improved, barrier-free coordinated operation of new energy and a large power grid is realized, the intelligentization level of a power supply system is improved, the disaster resistance is enhanced, and technical support is provided for improving the service quality of power utilization regions.
Referring to fig. 6, in an embodiment of the present application, there is provided a microgrid operation control apparatus, including:
the parameter acquisition module 01 is used for determining the running state of a grid-connected point of the micro-grid and the voltage value of a bus of the micro-grid;
the strategy determining module 02 is used for making a management strategy for the running states of different microgrid grid-connected points based on a peak-valley electricity price mechanism and making a corresponding control strategy according to different microgrid bus voltages;
and the control module 03 is used for controlling the operation of the microgrid by using a management strategy or a control strategy.
Referring to fig. 7, in an embodiment, the policy determination module 02 includes:
the grid-connected point normal operation control unit 021 is used for calculating the output power and the load power of a photovoltaic system in the microgrid when the grid-connected point is in a normal operation state;
when the output power is greater than the load power and the electric quantity supplied by the photovoltaic system is surplus, charging the energy storage battery until the energy storage battery is full, and transmitting the surplus electric energy to a large power grid;
when the output power is smaller than the load power and the electricity price is in the peak time period, determining an object for supplying power to the load according to the charge state of the energy storage battery;
when the output power is smaller than the load power and the electricity price is in a valley period, the photovoltaic system supplies power to the load, the large power grid provides the load power shortage, and the large power grid is used for charging the energy storage battery until the energy storage battery is fully charged;
when the output power is smaller than the load power and the electricity price is in a non-peak value or non-valley value time period, the energy storage battery is not charged and discharged, and the photovoltaic system and the commercial power supply jointly supply power for the load.
In an embodiment, the grid-connected point normal operation control unit 021 is further configured to:
if the state of charge of the energy storage battery is higher than the maximum value of the state of charge, the energy storage battery is used for supplying power to the load;
if the state of charge of the energy storage battery is between the minimum value and the maximum value of the state of charge and the provided electric energy is less than the load shortage power, purchasing the required electric quantity from the commercial power;
and if the state of charge of the energy storage battery is smaller than the minimum state of charge, stopping discharging the energy storage battery, and supplying power to the load by the photovoltaic system and the large power grid together.
In a certain embodiment, the policy determining module 02 further includes a first control unit 022 of a point-of-presence failure and a second control unit 023 of a point-of-presence failure, as shown in fig. 7, specifically:
the grid-connected point fault first control unit 022 is used for enabling the microgrid to meet the low voltage ride through requirement and keep grid-connected operation through the regulation of the superconducting current limiter when a grid-connected point is in fault and the current of a power grid is larger than the action current of the current limiter;
and the grid-connected point fault second control unit 023 is used for enabling the microgrid to meet the requirement of low voltage ride through and keep grid-connected operation through regulation of the photovoltaic inverter when the grid-connected point is in fault and the grid current is less than the action current of the current limiter.
In a certain embodiment, the policy determination module 02 further includes a third control unit 024 for grid-connected point fault, as shown in fig. 7, specifically:
and the grid-connected point fault third control unit 024 is used for issuing a control instruction to enable the microgrid to run off the grid when the grid-connected point has a fault and the regulated microgrid still does not meet the low-voltage ride-through requirement.
In an embodiment, the strategy determining module 02 further includes a bus voltage normal control unit 025, a bus voltage abnormal first control unit 026, and a bus voltage abnormal second control unit 027, as shown in fig. 7, specifically:
the bus voltage normal control unit 025 is used for enabling the composite superconducting energy storage device in the microgrid to stop acting when the bus voltage of the microgrid is in a normal operation state;
the first control unit 026 for bus voltage abnormality is used for determining the action of the energy storage battery or the composite superconducting energy storage device according to the voltage and current of the energy storage battery and the voltage and current of the composite superconducting energy storage device when the micro-grid bus voltage is disturbed and the composite superconducting energy storage device meets the starting condition;
the second control unit 027 is configured to control the voltage regulator to operate when the microgrid bus voltage is disturbed and the composite superconducting energy storage device does not meet the starting condition.
In an embodiment, the first control unit 026 for bus voltage anomaly is further configured to:
when the voltage of the composite superconducting energy storage device is greater than the maximum voltage limit value of the composite superconducting energy storage device and the voltage of the microgrid bus is greater than the charging starting voltage of the energy storage battery, controlling the composite superconducting energy storage device to absorb redundant electric energy of the load;
when the voltage of the microgrid bus is smaller than the maximum voltage limit value of the composite superconducting energy storage device and the current of the composite superconducting energy storage device is larger than the minimum current limit value of the composite superconducting energy storage device, controlling the composite superconducting energy storage device to enter a discharging mode;
and when the voltage of the composite superconducting energy storage device is smaller than the minimum voltage limit value of the composite superconducting energy storage device and the charging starting voltage of the energy storage battery is larger than the minimum voltage limit value of the composite superconducting energy storage device, compensating the energy storage battery.
It can be understood that the apparatus provided in this embodiment is used to execute the microgrid operation control method according to the foregoing embodiment, and achieve the same technical effects as those achieved by the foregoing method, and further description is omitted here.
In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical functional division, and there may be other divisions in actual practice, for example, multiple units or page components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed coupling or direct coupling or communication connection between each other may be through some interfaces, indirect coupling or communication connection between devices or units, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, or in a form of hardware plus a software functional unit.
The integrated unit implemented in the form of a software functional unit may be stored in a computer readable storage medium. The software functional unit is stored in a storage medium and includes several instructions to enable a computer device (which may be a personal computer, a server, or a network device) or a processor (processor) to execute some steps of the methods according to the embodiments of the present application. And the aforementioned storage medium includes: various media capable of storing program codes, such as a usb disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions in the embodiments of the present application.

Claims (15)

1. A microgrid operation control method is characterized by comprising the following steps:
determining the running state of a grid-connected point of the microgrid and the voltage value of a microgrid bus;
based on a peak-valley electricity price mechanism, establishing management strategies for the running states of different microgrid grid-connected points, and establishing corresponding control strategies according to different microgrid bus voltages;
and controlling the operation of the microgrid by using a management strategy or a control strategy.
2. The microgrid operation control method according to claim 1, wherein the establishing of management strategies for operation states of different microgrid grid-connected points based on a peak-valley electricity price mechanism comprises:
when the grid-connected point is in a normal operation state, calculating the output power and the load power of a photovoltaic system in the microgrid;
when the output power is greater than the load power and the electric quantity supplied by the photovoltaic system is surplus, charging the energy storage battery until the energy storage battery is full, and transmitting the surplus electric energy to a large power grid;
when the output power is smaller than the load power and the electricity price is in the peak time period, determining an object for supplying power to the load according to the charge state of the energy storage battery;
when the output power is smaller than the load power and the electricity price is in a valley period, the photovoltaic system supplies power to the load, the large power grid provides the load power shortage, and the large power grid is used for charging the energy storage battery until the energy storage battery is fully charged;
when the output power is smaller than the load power and the electricity price is in a non-peak value or non-valley value time period, the energy storage battery is not charged and discharged, and the photovoltaic system and the commercial power supply jointly supply power for the load.
3. The microgrid operation control method of claim 2, wherein the determining of an object for supplying power to the load according to the state of charge of the energy storage battery when the output power is less than the load power and the electricity price is in a peak period comprises:
if the state of charge of the energy storage battery is higher than the maximum value of the state of charge, the energy storage battery is used for supplying power to the load;
if the state of charge of the energy storage battery is between the minimum value and the maximum value of the state of charge and the provided electric energy is less than the load shortage power, purchasing the required electric quantity from the commercial power;
and if the state of charge of the energy storage battery is smaller than the minimum state of charge, stopping discharging the energy storage battery, and supplying power to the load by the photovoltaic system and the large power grid together.
4. The microgrid operation control method according to claim 2, wherein the management strategy is formulated for operation states of different microgrid grid-connected points based on a peak-valley electricity price mechanism, and further comprising:
when a grid-connected point has a fault and the current of a power grid is greater than the action current of a current limiter, the micro-grid meets the requirement of low voltage ride through and keeps grid-connected operation through the regulation of a superconducting current limiter;
when the grid-connected point has a fault and the current of the power grid is smaller than the action current of the current limiter, the photovoltaic inverter is used for adjusting to enable the micro-grid to meet the requirement of low voltage ride through and keep grid-connected operation.
5. The microgrid operation control method according to claim 2, wherein the management strategy is formulated for operation states of different microgrid grid-connected points based on a peak-valley electricity price mechanism, and further comprising:
and when the grid-connected point has a fault and the micro-grid still does not meet the low-voltage ride-through requirement after adjustment, issuing a control instruction to enable the micro-grid to run off-grid.
6. The microgrid operation control method according to claim 1, wherein the making of corresponding control strategies according to different microgrid bus voltages comprises:
when the voltage of the microgrid bus is in a normal operation state, the composite superconducting energy storage device in the microgrid does not act;
when the voltage of the microgrid bus is disturbed and the composite superconducting energy storage device meets the starting condition, determining the action of the energy storage battery or the composite superconducting energy storage device according to the voltage and the current of the energy storage battery and the voltage and the current of the composite superconducting energy storage device;
and when the voltage of the microgrid bus is disturbed and the composite superconducting energy storage device does not meet the starting condition, controlling the action of the voltage regulator.
7. The microgrid operation control method according to claim 6, wherein when a disturbance occurs to a microgrid bus voltage and the composite superconducting energy storage device meets a starting condition, determining an action of the energy storage battery or the composite superconducting energy storage device according to the voltage and current of the energy storage battery and the voltage and current of the composite superconducting energy storage device comprises:
when the current of the composite superconducting energy storage device is smaller than the maximum current limit value of the composite superconducting energy storage device and the voltage of the microgrid bus is larger than the voltage of the composite superconducting energy storage device, controlling the composite superconducting energy storage device to charge;
when the voltage of the composite superconducting energy storage device is greater than the maximum voltage limit value of the composite superconducting energy storage device and the voltage of a microgrid bus is greater than the charging starting voltage of the energy storage battery, the composite superconducting energy storage device is controlled to absorb redundant electric energy of a load;
when the voltage of the microgrid bus is smaller than the maximum voltage limit value of the composite superconducting energy storage device and the current of the composite superconducting energy storage device is larger than the minimum current limit value of the composite superconducting energy storage device, controlling the composite superconducting energy storage device to enter a discharging mode;
and when the voltage of the composite superconducting energy storage device is smaller than the minimum voltage limit value of the composite superconducting energy storage device and the charging starting voltage of the energy storage battery is larger than the minimum voltage limit value of the composite superconducting energy storage device, compensating the energy storage battery.
8. A microgrid operation control apparatus, comprising:
the parameter acquisition module is used for determining the running state of a grid-connected point of the micro-grid and the voltage value of a bus of the micro-grid;
the strategy determining module is used for making a management strategy for the running states of different microgrid grid-connected points based on a peak-valley electricity price mechanism and making a corresponding control strategy according to different microgrid bus voltages;
and the control module is used for controlling the operation of the microgrid by utilizing a management strategy or a control strategy.
9. The microgrid operation control device according to claim 8, wherein the policy determination module comprises a grid-connected point normal operation control unit, and is configured to:
when the grid-connected point is in a normal operation state, calculating the output power and the load power of a photovoltaic system in the microgrid;
when the output power is greater than the load power and the electric quantity supplied by the photovoltaic system is surplus, charging the energy storage battery until the energy storage battery is full, and transmitting the surplus electric energy to a large power grid;
when the output power is smaller than the load power and the electricity price is in the peak time period, determining an object for supplying power to the load according to the charge state of the energy storage battery;
when the output power is smaller than the load power and the electricity price is in the valley period, the photovoltaic system supplies power to the load, the large power grid provides the load power shortage, and the large power grid is used for charging the energy storage battery until the energy storage battery is fully charged;
when the output power is smaller than the load power and the electricity price is in a non-peak value or non-valley value time period, the energy storage battery is not charged and discharged, and the photovoltaic system and the commercial power supply jointly supply power for the load.
10. The microgrid operation control device according to claim 9, wherein the grid-connected point normal operation control unit is further configured to:
if the state of charge of the energy storage battery is higher than the maximum value of the state of charge, the energy storage battery is used for supplying power to the load;
if the state of charge of the energy storage battery is between the minimum value and the maximum value of the state of charge, and the provided electric energy is less than the load shortage power, purchasing the required electric quantity from the commercial power;
and if the state of charge of the energy storage battery is smaller than the minimum state of charge, stopping discharging the energy storage battery, and supplying power to the load by the photovoltaic system and the large power grid together.
11. The microgrid operation control apparatus of claim 9, wherein the policy determination module further comprises:
the grid-connected point fault first control unit is used for enabling the micro-grid to meet the low-voltage ride-through requirement and keep grid-connected operation through the regulation of the superconducting current limiter when a grid-connected point is in fault and the current of the power grid is larger than the action current of the current limiter;
and the grid-connected point fault second control unit is used for enabling the micro-grid to meet the low-voltage ride-through requirement and keep grid-connected operation through the regulation of the photovoltaic inverter when the grid-connected point is in fault and the current of the power grid is smaller than the action current of the current limiter.
12. The microgrid operation control device of claim 9, wherein the policy determination module further comprises a grid-connected point fault third control unit configured to:
and when the grid-connected point has a fault and the micro-grid still does not meet the low-voltage ride-through requirement after adjustment, issuing a control instruction to enable the micro-grid to run off-grid.
13. The microgrid operation control apparatus of claim 8, wherein the policy determination module further comprises:
the bus voltage normal control unit is used for enabling the composite superconducting energy storage device in the microgrid not to act when the bus voltage of the microgrid is in a normal operation state;
the first control unit for bus voltage abnormity is used for determining the action of the energy storage battery or the composite superconducting energy storage device according to the voltage and the current of the energy storage battery and the voltage and the current of the composite superconducting energy storage device when the voltage of the microgrid bus is disturbed and the composite superconducting energy storage device meets the starting condition;
and the second control unit for controlling the action of the voltage regulator when the voltage of the microgrid bus is disturbed and the composite superconducting energy storage device does not meet the starting condition.
14. The microgrid operation control device of claim 13, wherein the bus voltage abnormality first control unit is further configured to:
when the voltage of the composite superconducting energy storage device is greater than the maximum voltage limit value of the composite superconducting energy storage device and the voltage of the microgrid bus is greater than the charging starting voltage of the energy storage battery, controlling the composite superconducting energy storage device to absorb redundant electric energy of the load;
when the voltage of the microgrid bus is smaller than the maximum voltage limit value of the composite superconducting energy storage device and the current of the composite superconducting energy storage device is larger than the minimum current limit value of the composite superconducting energy storage device, controlling the composite superconducting energy storage device to enter a discharging mode;
and when the voltage of the composite superconducting energy storage device is smaller than the minimum voltage limit value of the composite superconducting energy storage device and the charging starting voltage of the energy storage battery is larger than the minimum voltage limit value of the composite superconducting energy storage device, compensating the energy storage battery.
15. A microgrid, comprising:
the system comprises a superconducting current limiter, a photovoltaic system, a photovoltaic inverter, a three-winding transformer, a composite superconducting energy storage device, a rectifier and a microgrid bus;
each load is connected to the microgrid bus through the superconducting current limiter;
the photovoltaic system is connected to a pc circuit through the photovoltaic inverter, the three-winding transformer and the superconducting current limiter in sequence;
and the composite superconducting energy storage device is connected to the microgrid bus through the rectifier.
CN202210423088.2A 2022-04-21 2022-04-21 Microgrid operation control method and device and microgrid Pending CN114629174A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116191515A (en) * 2023-03-28 2023-05-30 上海艾临科智能科技有限公司 Charging and discharging parameter control method and device for alternating-current side energy storage device and electronic equipment
CN116505570A (en) * 2022-12-20 2023-07-28 国网山东省电力公司济宁供电公司 Four-port intelligent soft switch system without central controller and control method thereof

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116505570A (en) * 2022-12-20 2023-07-28 国网山东省电力公司济宁供电公司 Four-port intelligent soft switch system without central controller and control method thereof
CN116505570B (en) * 2022-12-20 2024-02-09 国网山东省电力公司济宁供电公司 Four-port intelligent soft switch system without central controller and control method thereof
CN116191515A (en) * 2023-03-28 2023-05-30 上海艾临科智能科技有限公司 Charging and discharging parameter control method and device for alternating-current side energy storage device and electronic equipment
CN116191515B (en) * 2023-03-28 2023-12-15 上海艾临科智能科技有限公司 Charging and discharging parameter control method and device for alternating-current side energy storage device and electronic equipment

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