CN114243754B - Self-adaptive off-grid energy storage response control method and control system - Google Patents
Self-adaptive off-grid energy storage response control method and control system Download PDFInfo
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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
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
- H02J3/241—The oscillation concerning frequency
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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
- H02J3/28—Arrangements for balancing of the load in a network by storage of energy
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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
- 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
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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
Abstract
The application discloses self-adaptive off-grid energy storage response control method and control system, which support a micro-grid by adopting a centralized off-grid energy storage response controller, and specifically comprises the following steps: and predicting the voltage and frequency changes of the micro-grid at a certain moment in the future when the micro-grid is off-grid and on-grid according to the historical data in a short period of time, and generating the power absorbed or released by the energy storage units based on the voltage and frequency changes. The control strategy is continuously updated in real time along with the running state of the power grid, when the power grid is not off-grid in a preset unit period, the constructed strategy is abolished, a new strategy is generated again according to the history and the current data, and preparation is performed at any time to find the closest time. After the strategy is generated, each energy storage unit is controlled to output power according to the requirement, so that larger power and voltage fluctuation can be prevented when the micro-grid is connected and is converted from grid to grid, the stable operation of the micro-grid is ensured, and the power supply reliability of the grid is improved.
Description
Technical Field
The application relates to the technical field of micro-grids, in particular to a self-adaptive off-grid energy storage response control method and a control system.
Background
In recent years, with rapid development of renewable energy power generation technology, energy storage technology, small hydropower technology and load control technology, a large number of power electronic devices such as distributed renewable energy power generation are connected to a 400V low-voltage distribution network to construct a renewable energy micro-grid system (hereinafter referred to as micro-grid for short). In order to reduce loss caused by power failure and ensure the reliability of important load power supply, the micro-grid is required to have a parallel/off-grid dual-mode operation function. In addition, as a large-scale distributed power supply is connected to a low-voltage power distribution network, particularly at the tail end of a mountain power grid, a large number of light storage integrated machines and energy storage type power grid management devices enter a micro-grid, power flow of the power grid is changed, a load structure also tends to be complicated and developed, and a large number of capacitive loads and inductive loads are mainly connected to the low-voltage power distribution network.
In the grid-connected mode, the low-voltage micro-grid can basically keep the voltage and the frequency of the grid stable due to the clamping effect of the main grid, and ensure the stable operation of the load. However, when the micro-grid is in off-grid operation, i.e. the micro-grid is out of the clamp of the main grid and is operated by independently supporting the load, unstable properties of the power supply voltage and the frequency generated in the micro-grid area can damage the electric equipment. Especially, when the low-voltage micro-grid is connected or disconnected, the power supply environment and the power flow of the grid are changed, so that the voltage, the power and the frequency of the grid are fluctuated, and the grid-connected or disconnected switching fails seriously.
Disclosure of Invention
The application provides a self-adaptive off-grid energy storage response control method and a control system, which are used for solving the problems that the voltage, the power and the frequency of a power grid fluctuate due to the change of the power supply environment and the power flow of the power grid at the moment of grid connection or off-grid of a micro power grid, and the off-grid switching failure possibly occurs in severe cases. The self-adaptive off-grid energy storage response control method and the control system do not have the voltage source networking function.
In a first aspect, the present application provides an adaptive off-grid energy storage response control method, comprising,
step S100, acquiring historical energy storage unit power p, and judging that the energy storage unit absorbs power to a power grid if the energy storage unit power p is more than or equal to 0; if the power p of the energy storage unit is less than 0, judging that the energy storage unit releases power to the power grid;
step S200, calculating the change coefficient of the released power voltage in each preset unit time period by using the historical data of the power gridOr absorption power voltage variation coefficient->Wherein DeltaU d To discharge the outlet voltage difference caused by power DeltaU c For an outlet voltage difference caused by charging power, the coefficient k is equal to the varying voltage divided by the varying power;
step S300, budgeting the power release or absorption situation of the energy storage unit at off-grid time, specifically including,
step S310, when the sum current of the multiple energy storage units is less than 0, calculating the released power of the energy storage units to the micro-grid and the released power of each energy storage unit;
step S320, when the sum current of the multiple energy storage units is more than 0, calculating the absorption power of the energy storage units to the micro-grid and the absorption power of each energy storage unit;
step S400, according to the total outlet voltage change rate of the micro-gridOr micro-electricityNetwork frequency f t Adaptive release or absorption power control,
wherein, according to the total outlet voltage change rate of the micro-grid, the self-adaptive release or absorption power control specifically comprises: total outlet voltage rate of change when micro grid is grid connected and disconnectedWhen in use, triggering and off-line, wherein DeltaU w The calculation formula of (a) is delta U w ＝|U t0 -U t0-1 |-ΔU d -ΔU c ，U t0-1 The outlet voltage acquired for the previous preset unit period; u (U) t0 For the outlet voltage, lambda, acquired for the current preset unit period off Is a voltage change rate threshold;
depending on the microgrid frequency, the adaptive release or absorption power control specifically includes: when f t ≤f l If it is determined that the current is summed by a plurality of energy storage units<0, releasing power to the micro-grid by the energy storage unit, and executing step S310; when f t ≥f u If the sum current of the energy storage units is judged>0, the energy storage unit absorbs power from the micro-grid, and step S320 is performed, wherein f l Switching a lower threshold frequency for off-grid micro-grid; f (f) u And switching the upper threshold frequency for off-grid micro-grid.
In some embodiments, the calculating the power released by the energy storage unit to the micro-grid and the power released by each energy storage unit are as follows:
step S311, calculating the grid history contemporaneous maximum release power value p max Minimum voltage U min Sum voltage maximum U max Current minimum i min Maximum current i max Value, wherein the current is the lowest value i min Current at the lightest load;
step S312, the multi-energy storage unit releases the current summation Σi i When i min ≤∑i i ≤i max At the time, the controller release power P is calculated ac ＝i d ·U ac Wherein i is d Releasing current for the multi-energy storage unit at off-grid time of the micro-grid;
step S313, utilizing the historical synchronization unit of the released power voltage variation coefficientCalculating a micro-grid variation DeltaU when the released power varies d ＝α dis ·p ac ；
Step S314, judging the variation delta U of the micro-grid d Whether the micro-grid allowable surge voltage + -DeltaU range is satisfied,
when DeltaU d Not more than-DeltaU or DeltaU d When the voltage is more than delta U, calculating the release power of the energy storage unit at the off-grid moment of the micro-grid by taking the ratio of the allowable fluctuation voltage + -delta U range of the micro-grid and the change coefficient of the historical synchronous unit release power voltage
when-DeltaU < DeltaU d When delta U is less than or equal to delta U, calculating the increased release power of the energy storage unit at the off-grid moment of the micro-grid
Step S315, calculating the discharging current i of each energy storage unit at the off-grid time of the micro-grid d The calculation formula is as follows:step S316, calculating the distribution coefficient beta of the multi-energy storage unit release currents at the off-grid time of the micro-grid di The calculation formula is as follows:
step S317, calculating the remaining power W of each energy storage unit soci And the residual capacity absorption or release power P of each energy storage unit soci The calculation formula is as follows:
step S318, distributing beta according to the release current di Coefficient and residual capacity of each energy storage unit absorb or release power P soci Is correspondingly distributed to each storageEnergy unit releasing increased power P fi The method comprises the following steps of: p (P) f1 ＝β di ·P soc1 ......P fn ＝β di ·P socn When off-grid occurs, each energy storage unit is released with increased power P fi To the corresponding energy storage unit.
In some embodiments, the calculating the energy storage unit absorbs power to the micro-grid and each energy storage unit absorbs power is as follows:
step S321, when U ac ≥δ·U max In this case, the absorption power DeltaP is increased on the base layer of the original absorption power ch Increase the absorption power Δp ch The method comprises the following steps: ΔP ch ＝P max_h -P ac +P no_load Wherein P is ac For current absorbed power, P max_h For historic contemporaneous maximum absorbed power, p no_load Derating power for non-primary loads;
step S322, according to the historical synchronous unit absorbed power voltage change coefficientCalculating the voltage variation delta U c The calculation formula is as follows: deltaU c ＝α cha ·ΔP ch ；
Step S323, determining the variation DeltaU c Whether the allowable fluctuation voltage + -delta U range of the micro-grid is met or not, when delta U is more than delta U d When delta U is larger than delta U, the absorption power of the multi-energy storage unit at the off-grid moment of the micro-grid is calculatedwhen-DeltaU < DeltaU d When delta U is less than or equal to delta U, calculating the absorption power of the multi-energy storage unit at the off-grid moment of the micro-grid +.>
Step S324, calculating the absorption current of the multiple energy storage units at the off-grid time of the micro-gridAbsorption current distribution coefficient->The remaining capacity of each energy storage unit absorbs or releases power +.>And the power P absorbed by each energy storage unit fi The method comprises the following steps of: p (P) f1 ＝(1+β 1 )·P soc1 ......P fn ＝(1+β 1 )·P socn When off-grid occurs, the power P absorbed by each energy storage unit fi To the corresponding energy storage unit, wherein U ac For the outlet voltage, W suri Is the rated capacity of the energy storage unit;
step S325, when U ac ＜δ·U max And when the power factor alpha is output, the plurality of energy storage units correspondingly absorb power.
In some embodiments, the power factor α principle: when the power factor alpha is more than 0.9 and less than or equal to 1, the self-adaptive off-grid energy storage response controller controls the energy storage unit to absorb or release active power;
when the power factor alpha is less than or equal to 0.9, the self-adaptive off-grid energy storage response controller controls the energy storage unit to absorb or release part of reactive power.
The application also provides a self-adaptive off-grid energy storage response control system, which is characterized by comprising a controller, a multi-interface multi-protocol communication module, a short circuit monitoring module, a contactor driving module, a voltage sensor, n current sensors, n contactors and n energy storage units, wherein the multi-interface multi-protocol communication module, the short circuit monitoring module, the contactor driving module, the voltage sensor, the n current sensors, the n contactors and the n energy storage units are all connected with the controller, and n is a positive integer;
the input end of each contactor is connected with the micro-grid and a voltage sensor connected in parallel on the micro-grid, and the voltage sensor is used for monitoring the total outlet voltage of the controller; the output ends of the n contactors are respectively and correspondingly connected with a current sensor and an energy storage unit;
the data output of the current sensor is connected with a common data line, one end of the common data line is connected with the data input end of the short circuit monitoring module, and the data output end of the short circuit monitoring module is connected with the data input end of the controller;
the controller is used for collecting the data of the n current sensors in the short circuit state of the n energy storage units, and is also used for collecting the data of the voltage sensors;
the control ends of the n contactors are correspondingly connected with n paths of output ends of the contactor driving module, and the data input end of the contactor driving module is connected with the data output end of the controller; the controller controls the opening and closing of the contactor through the contactor driving module;
the contactor driving module comprises n locking control ends, the short circuit monitoring module comprises n short circuit control ends, and the n locking control ends are correspondingly connected with the n short circuit control ends;
the signal input end of the carrier receiving module is connected with the power grid, and the data analysis output end of the carrier receiving module is connected with the data input end of the controller;
the multi-interface multi-protocol communication module comprises n communication interfaces, each communication interface is connected with the corresponding communication interface of the energy storage unit through a communication line, the data output end of the multi-interface multi-protocol communication module is connected with the communication input and output end of the controller, and the controller is used for reading the data of the energy storage unit in real time.
The application provides a self-adaptive off-grid energy storage response control method and a control system, which support a micro-grid by adopting a centralized off-grid energy storage response controller, and specifically comprises the following steps: and predicting the voltage and frequency changes of the micro-grid at a certain moment in the future when the micro-grid is off-grid and on-grid according to the historical data in a short period of time, and generating the power absorbed or released by the energy storage units based on the voltage and frequency changes. Of course, in actual use, the control strategy is updated in real time along with the running state of the power grid, if the power grid does not get off the grid in the preset unit period of time before the former strategy, the strategy is abandoned, and a new strategy is generated again according to the history and the current data, so that preparation is made at any time to find the closest time. After the strategy is generated, each energy storage unit is controlled to output power according to the requirement, so that larger power and voltage fluctuation can be prevented when the micro-grid is connected and is converted from grid to grid, the stable operation of the micro-grid is ensured, and the power supply reliability of the grid is improved.
Drawings
In order to more clearly illustrate the technical solutions of the present application, the drawings that are needed in the embodiments will be briefly described below, and it will be obvious to those skilled in the art that other drawings can be obtained from these drawings without inventive effort.
Fig. 1 is a schematic structural diagram of an adaptive off-grid energy storage response control system according to the present application.
Detailed Description
In the actual running of the micro-grid at present, the voltage, the power and the frequency of the grid fluctuate due to the change of the power supply environment and the tide of the grid at the moment of grid connection or off-grid, and the problem of grid connection and off-grid switching failure can be caused when the voltage, the power and the frequency of the grid fluctuates seriously. For example, a plurality of photovoltaic, small hydroelectric and wind power are used for surfing the internet in the transformer area, and the voltage and power loss of the transformer area are affected. In order to optimize operation and improve power supply reliability, the application provides a self-adaptive off-grid energy storage response control method, wherein multiple energy storage units are used for regulating voltage or carrying out peak clipping and valley filling during grid connection, and power curve smoothing is adjusted, and each energy storage unit acts.
The self-adaptive off-grid energy storage response control method specifically comprises the following steps.
Step S100, acquiring historical energy storage unit power p, and judging that the energy storage unit absorbs power to a power grid if the energy storage unit power p is more than or equal to 0; and if the power p of the energy storage unit is less than 0, judging that the energy storage unit releases power to the power grid.
Step S200, calculating the change coefficient of the released power voltage in each preset unit time period by using the historical data of the power gridOr absorption power voltage variation coefficient->Wherein DeltaU d To discharge the outlet voltage difference caused by power DeltaU c For the outlet voltage difference caused by the charging power, the coefficient k is equal to the varying voltage divided by the varying power.
The power grid history data is described herein, and the power grid history data is power grid history data of at least one year or more, including voltage, current and power at each moment. In addition, for the preset unit period, those skilled in the art can set according to actual needs, for example, 15min or 20min, which all belong to the protection scope of the present application.
Step S300, the power release or absorption condition of the energy storage unit at the time of budget off-grid specifically comprises the following steps.
In step S310, when the sum current of the multiple energy storage units is less than 0, the energy storage unit release power to the micro-grid and each energy storage unit release power are calculated.
When releasing power p to micro-grid ac The current power of the controller is greater than the release maximum power p closest to the off-grid history time of the previous year max Subtracting non-vital load shedding power p no_load When the off-grid occurs, the energy storage unit should not release power.
In the application, the power released by the energy storage unit to the micro-grid and the power released by each energy storage unit are calculated as follows:
step S311, calculating the grid history contemporaneous maximum release power value p max Minimum voltage U min Sum voltage maximum U max Current minimum i min Maximum current i max Value, wherein the current is the lowest value i min The current at which the load is the lightest, i.e. the internet current.
Step S312, the multi-energy storage unit releases the current summation Σi i When i min ≤∑i i ≤i max At the time, the controller release power P is calculated ac ＝i d ·U ac Wherein i is d And releasing current for the multi-energy storage unit at the off-grid moment of the micro-grid.
Step S313, utilizing the historical synchronization unit of the released power voltage variation coefficientCalculating a micro-grid variation DeltaU when the released power varies d ＝α dis ·p ac 。
Step S314, judging whether the micro-scale is smallGrid variation deltaU d Whether the micro-grid allowable surge voltage + -DeltaU range is satisfied,
when DeltaU d Not more than-DeltaU or DeltaU d When the voltage is more than delta U, calculating the release power of the energy storage unit at the off-grid moment of the micro-grid by taking the ratio of the allowable fluctuation voltage + -delta U range of the micro-grid and the change coefficient of the historical synchronous unit release power voltage
when-DeltaU < DeltaU d When delta U is less than or equal to delta U, calculating the increased release power of the energy storage unit at the off-grid moment of the micro-grid
Step S315, calculating the discharging current i of each energy storage unit at the off-grid time of the micro-grid d The calculation formula is as follows:
step S316, calculating the distribution coefficient beta of the multi-energy storage unit release currents at the off-grid time of the micro-grid di The calculation formula is as follows:
step S317, calculating the remaining power W of each energy storage unit soci And the residual capacity absorption or release power P of each energy storage unit soci The calculation formula is as follows:
step S318, distributing beta according to the release current di Coefficient and residual capacity of each energy storage unit absorb or release power P soci Correspondingly obtains the release power P distributed to each energy storage unit fi The method comprises the following steps of: p (P) f1 ＝β di ·P soc1 ......P fn ＝β di ·P socn When off-grid occurs, each energy storage unit is released with increased power P fi To the corresponding energy storage unit. Due to the capacity, work of each energy storage unitThe rate is different, so the release power allocated to each energy storage capacity is different, the larger the capacity is, the more release power is, and the release allocation coefficient is multiplied by each energy storage output power respectively, so that the increased release power of each energy storage unit is obtained.
In step S320, when the sum current of the multiple energy storage units is >0, the energy storage units absorb power to the micro-grid and each energy storage unit absorbs power.
In the application, the calculation energy storage unit absorbs power to the micro-grid and each energy storage unit absorbs power, and the calculation energy storage unit specifically comprises the following steps:
step S321, when U ac ≥δ·U max In this case, the absorption power DeltaP is increased on the base layer of the original absorption power ch Increase the absorption power Δp ch The method comprises the following steps: ΔP ch ＝P max_h -P ac +P no_load Wherein P is ac For current absorbed power, P max_h For historic contemporaneous maximum absorbed power, p no_load Power is offloaded for non-primary loads.
Step S322, according to the historical synchronous unit absorbed power voltage change coefficientCalculating the voltage variation delta U c The calculation formula is as follows: deltaU c ＝α cha ·ΔP ch 。
Step S323, determining the variation DeltaU c Whether the allowable fluctuation voltage + -delta U range of the micro-grid is met or not, when delta U is more than delta U d When delta U is larger than delta U, the absorption power of the multi-energy storage unit at the off-grid moment of the micro-grid is calculatedwhen-DeltaU < DeltaU d When delta U is less than or equal to delta U, calculating the absorption power of the multi-energy storage unit at the off-grid moment of the micro-grid +.>
Step S324, calculating the absorption current of the multiple energy storage units at the off-grid time of the micro-gridAbsorption current distribution coefficient->The remaining capacity of each energy storage unit absorbs or releases power +.>And the power P absorbed by each energy storage unit fi The method comprises the following steps of: p (P) f1 ＝(1+β 1 )·P soc1 ......P fn ＝(1+β 1 )·P socn When off-grid occurs, the power P absorbed by each energy storage unit fi To the corresponding energy storage unit, wherein U ac For the outlet voltage, W suri Is the rated capacity of the energy storage unit. Since the capacity and the power of each energy storage unit are different, the release power distributed to each energy storage capacity is different, the larger the capacity is, the more the release power is, and the release distribution coefficient is multiplied by each energy storage output power respectively, so that the increased release power of each energy storage unit is obtained.
Step S325, when U ac ＜δ·U max And when the power factor alpha is output, the plurality of energy storage units correspondingly absorb power. In this application, the power factor α principle: when the power factor alpha is more than 0.9 and less than or equal to 1, the self-adaptive off-grid energy storage response controller controls the energy storage unit to absorb or release active power; when the power factor alpha is less than or equal to 0.9, the self-adaptive off-grid energy storage response controller controls the energy storage unit to absorb or release part of reactive power.
Step S400, according to the total outlet voltage change rate of the micro-gridOr micro-grid frequency f t Adaptive release or absorption power control.
In order to ensure reliable identification of the state of the micro-grid, the method adopts two modes to identify the grid-connected/off-grid state, and the priority triggering identification condition is the voltage change rate of the micro-grid
Wherein, according to the total outlet voltage change rate of the micro-grid, the self-adaptive release or absorption power control specifically comprises: total outlet voltage rate of change when micro grid is grid connected and disconnectedWhen in use, triggering and off-line, wherein DeltaU w The calculation formula of (a) is delta U w ＝|U t0 -U t0-1 |-ΔU d -ΔU c ，U t0-1 The outlet voltage acquired for the previous preset unit period; u (U) t0 For the outlet voltage, lambda, acquired for the current preset unit period off Is a voltage change rate threshold.
Depending on the microgrid frequency, the adaptive release or absorption power control specifically includes: when f t ≤f l If it is determined that the current is summed by a plurality of energy storage units<0, releasing power to the micro-grid by the energy storage unit, and executing step S310; when f t ≥f u If the sum current of the energy storage units is judged>0, the energy storage unit absorbs power from the micro-grid, and step S320 is performed, wherein f l Switching a lower threshold frequency for off-grid micro-grid; f (f) u And switching the upper threshold frequency for off-grid micro-grid.
The application provides a self-adaptive off-grid energy storage response control system, and fig. 1 is a schematic structural diagram of the self-adaptive off-grid energy storage response control system of the application, as shown in fig. 1, the self-adaptive off-grid energy storage response control system includes: controller, multi-interface multi-protocol communication module, short circuit monitoring module, contactor driving module, voltage sensor V, n current sensors (A 1 、A 2 …A n ) N contactors (K) 1 、K 2 …K n ) And n energy storage units (energy storage unit 1, energy storage unit 2 … energy storage unit n), wherein n is a positive integer.
The input end of each contactor is connected with the micro-grid and a voltage sensor connected in parallel on the micro-grid, and the voltage sensor is used for monitoring the total outlet voltage of the controller; the output ends of the n contactors are respectively and correspondingly connected with a current sensor and an energy storage unit.
The data output of the current sensor is connected with a common data line, one end of the common data line is connected with the data input end of the short circuit monitoring module, and the data output end of the short circuit monitoring module is connected with the data input end of the controller.
The controller is used for collecting the data of the n current sensors in the short circuit state of the n energy storage units, and is also used for collecting the data of the voltage sensors.
The control ends of the n contactors are correspondingly connected with n paths of output ends of the contactor driving module, and the data input end of the contactor driving module is connected with the data output end of the controller; the controller controls the opening and closing of the contactor through the contactor driving module.
The contactor driving module comprises n locking control ends, the short circuit monitoring module comprises n short circuit control ends, and the n locking control ends are correspondingly connected with the n short circuit control ends.
The signal input end of the carrier wave receiving module is connected with the power grid, and the data analysis output end of the carrier wave receiving module is connected with the data input end of the controller.
The multi-interface multi-protocol communication module comprises n communication interfaces, each communication interface is connected with the corresponding communication interface of the energy storage unit through a communication line, the data output end of the multi-interface multi-protocol communication module is connected with the communication input and output end of the controller, and the controller is used for reading the data of the energy storage unit in real time.
The application provides a self-adaptive off-grid energy storage response control method and a control system, which are based on carrier communication, power prediction, frequency analysis, load and energy storage unit control, and realize that a micro-grid is reliably switched without disturbance and a stable power grid is a future micro-grid demand under the dual-mode of off-grid and on-grid.
The foregoing is illustrative of the best mode of carrying out the invention, and is not presented in any detail as is known to those of ordinary skill in the art. The protection scope of the invention is defined by the claims, and any equivalent transformation based on the technical teaching of the invention is also within the protection scope of the invention.
Claims (3)
1. A self-adaptive off-grid energy storage response control method is characterized by comprising the following steps of,
step S100, acquiring historical energy storage unit power p, and judging that the energy storage unit absorbs power to a power grid if the energy storage unit power p is more than or equal to 0; if the power p of the energy storage unit is less than 0, judging that the energy storage unit releases power to the power grid;
step S200, calculating the change coefficient of the released power voltage in each preset unit time period by using the historical data of the power gridOr absorption power voltage variation coefficient->Wherein DeltaU d To discharge the outlet voltage difference caused by power DeltaU c To absorb the outlet voltage difference caused by power, the coefficient k is equal to the varying voltage divided by the varying power;
step S300, calculating the power release or absorption situation of the energy storage unit at off-grid time, which specifically includes,
step S310, when the sum current of the multiple energy storage units is less than 0, calculating the released power of the energy storage units to the micro-grid and the released power of each energy storage unit;
step S320, when the sum current of the multiple energy storage units is more than 0, calculating the absorption power of the energy storage units to the micro-grid and the absorption power of each energy storage unit;
step S400, according to the total outlet voltage change rate of the micro-gridOr micro-grid frequency f t Adaptive release or absorption power control,
wherein, according to the total outlet voltage change rate of the micro-grid, the self-adaptive release or absorption power control specifically comprises: total outlet voltage rate of change when micro grid is grid connected and disconnectedWhen the network is disconnected, triggering the network disconnection, wherein delta U w The calculation formula of (a) is delta U w ＝|U t0 -U t0-1 |-ΔU d -ΔU c ，U t0-1 The outlet voltage acquired for the previous preset unit period; u (U) t0 For the outlet voltage, lambda, acquired for the current preset unit period off Is a voltage change rate threshold;
depending on the microgrid frequency, the adaptive release or absorption power control specifically includes: when f t ≤f l If it is determined that the current is summed by a plurality of energy storage units<0, releasing power to the micro-grid by the energy storage unit, and executing step S310; when f t ≥f u If the sum current of the energy storage units is judged>0, the energy storage unit absorbs power from the micro-grid, and step S320 is performed, wherein f l Switching a lower threshold frequency for off-grid micro-grid; f (f) u And switching the upper threshold frequency for off-grid micro-grid.
2. The method according to claim 1, wherein the calculating the energy storage unit releasing power to the micro grid and each energy storage unit releasing power is as follows:
step S311, calculating the grid history contemporaneous maximum release power value p max Minimum voltage U min Sum voltage maximum U max Current minimum i min Maximum current i max Wherein the current is the lowest value i min Current at the lightest load;
step S312, the multi-energy storage unit releases the current summation Σi i When i min ≤∑i i ≤i max At the time, the current release power P is calculated ac ＝i d ·U ac Wherein i is d Releasing current for multiple energy storage units at off-grid time of micro-grid, U ac For the energy storage unit outlet voltage;
step S313 of releasing the power voltage variation coefficient in each preset unit periodCalculating the outlet voltage difference DeltaU caused by the released power d ＝α dis ·p ac ；
Step S314, determining an outlet voltage difference DeltaU caused by the released power d Whether the micro-grid allowable surge voltage + -DeltaU range is satisfied,
when DeltaU d Not more than-DeltaU or DeltaU d When the voltage is more than delta U, calculating the release power of the energy storage unit at the off-grid moment of the micro-grid by taking the ratio of the allowable fluctuation voltage + -delta U range of the micro-grid and the change coefficient of the historical synchronous unit release power voltage
when-DeltaU < DeltaU d When delta U is less than or equal to delta U, calculating the release power of the energy storage unit at the off-grid moment of the micro-grid
Step S315, calculating the multi-energy storage unit release current i at the off-grid time of the micro-grid d The calculation formula is as follows:step S316, calculating the distribution coefficient beta of the multi-energy storage unit release currents at the off-grid time of the micro-grid di The calculation formula is as follows: />
Step S317, calculating the remaining power W of each energy storage unit soci And the residual capacity absorption or release power P of each energy storage unit soci The calculation formula is as follows:
step S318, according to the release current distribution coefficient beta of the multi-energy storage unit at the off-grid time of the micro-grid di And the residual capacity of each energy storage unit absorbs or releases power P soci Is correspondingly distributed to each energy storagePower P released by the cell fi The method comprises the following steps of: p (P) f1 ＝β di ·P soc1 ，……，P fn ＝β di ·P socn When off-grid occurs, the power P released by each energy storage unit is calculated fi To the corresponding energy storage unit.
3. The self-adaptive off-grid energy storage response control system is characterized by comprising a controller, a multi-interface multi-protocol communication module, a carrier wave receiving module, a short circuit monitoring module, a contactor driving module, a voltage sensor, n current sensors, n contactors and n energy storage units, wherein the multi-interface multi-protocol communication module, the carrier wave receiving module, the short circuit monitoring module, the contactor driving module, the voltage sensor, the n contactors and the n energy storage units are all connected with the controller, and n is a positive integer;
the input end of each contactor is connected with the micro-grid and a voltage sensor connected in parallel on the micro-grid, and the voltage sensor is used for monitoring the total outlet voltage of the controller; the output ends of the n contactors are respectively and correspondingly connected with a current sensor and an energy storage unit;
the data output of the current sensor is connected with a common data line, one end of the common data line is connected with the data input end of the short circuit monitoring module, and the data output end of the short circuit monitoring module is connected with the data input end of the controller;
the controller is used for collecting the data of the n current sensors in the short circuit state of the n energy storage units, and is also used for collecting the data of the voltage sensors;
the control ends of the n contactors are correspondingly connected with n paths of output ends of the contactor driving module, and the data input end of the contactor driving module is connected with the data output end of the controller; the controller controls the opening and closing of the contactor through the contactor driving module;
the contactor driving module comprises n locking control ends, the short circuit monitoring module comprises n short circuit control ends, and the n locking control ends are correspondingly connected with the n short circuit control ends;
the signal input end of the carrier receiving module is connected with the power grid, and the data analysis output end of the carrier receiving module is connected with the data input end of the controller;
the multi-interface multi-protocol communication module comprises n communication interfaces, each communication interface is connected with the corresponding communication interface of the energy storage unit through a communication line, the data output end of the multi-interface multi-protocol communication module is connected with the communication input and output end of the controller, and the controller is used for reading the data of the energy storage unit in real time.
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