CN108365620B - Method and device for simulating energy storage system based on equivalent model - Google Patents
Method and device for simulating energy storage system based on equivalent model Download PDFInfo
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- CN108365620B CN108365620B CN201810131405.7A CN201810131405A CN108365620B CN 108365620 B CN108365620 B CN 108365620B CN 201810131405 A CN201810131405 A CN 201810131405A CN 108365620 B CN108365620 B CN 108365620B
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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
- H02J3/32—Arrangements for balancing of the load in a network by storage of energy using batteries with converting means
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
- H02J2203/20—Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]
Abstract
A method and a device for simulating an energy storage system based on an equivalent model comprise the following steps: acquiring scheduling requirements, power generation data of a power grid and calculating the charge state of a battery pack in each energy storage unit at the next moment; and substituting the scheduling requirement, the power generation data of the power grid and the charge state of the battery pack in each energy storage unit into a pre-constructed equivalent model for calculation to obtain the operation data of the energy storage subsystem until the simulation is finished. According to the invention, equivalent energy storage units are combined through the equivalent model, so that the complexity of the simulation model in the energy storage system is reduced, and the external characteristics of the energy storage power station are close to a detailed model, thereby ensuring the effectiveness of simulation.
Description
Technical Field
The invention relates to the field of new energy power generation, in particular to a method and a device for simulating an energy storage system based on an equivalent model.
Background
With the continuous development of new energy technology, solar energy and wind energy become representatives of new energy sources with the advantages of cleanness, no pollution, renewability and the like. The large-scale energy storage system promotes the development of photovoltaic and wind power generation; and the functions of smooth output, peak clipping and valley filling, tracking planned output and the like can be realized by matching with a photovoltaic generator set and a wind turbine generator set, so that the controllability of power generation is increased, the randomness and the volatility of a power generation system are reduced, and the grid-connected capability of wind and light power generation is improved. However, when a large-scale battery energy storage system runs, a network structure system is complex, the number of battery packs and energy storage converters is large, the problem that a simulation result is difficult to obtain in a short time exists, and the research and development of the energy storage system are not facilitated.
Disclosure of Invention
In order to solve the defects in the prior art, the invention provides a method and a device for simulating an energy storage system based on an equivalent model. On the premise that the energy storage system is divided into a plurality of energy storage units, the power of each energy storage unit is reasonably distributed, a virtual synchronous machine control mode is adopted, and equivalent calculation is carried out on the energy storage units with similar working states by establishing an equivalent judgment standard, so that the simulation speed is increased.
The technical scheme provided by the invention is as follows: a method for simulating an energy storage system based on an equivalent model comprises the following steps:
acquiring scheduling requirements, power generation data of a power grid and calculating the charge state of a battery pack in each energy storage unit at the next moment;
and substituting the scheduling requirement, the power generation data of the power grid and the charge state of the battery pack in each energy storage unit into a pre-constructed equivalent model for calculation to obtain the operation data of the energy storage subsystem until the simulation is finished.
Preferably, the construction of the equivalent model includes:
distributing scheduling requirements to each energy storage unit according to the initial charge state of the battery pack in each energy storage unit;
calculating a power angle value of the virtual synchronous machine corresponding to each energy storage unit according to the scheduling requirements distributed to each energy storage unit;
merging the energy storage units with the power angle change of the virtual synchronous machine smaller than a threshold value into an energy storage subsystem;
performing equivalence calculation inside each energy storage subsystem;
and constructing an equivalence model based on the energy storage subsystem subjected to equivalence calculation.
Preferably, the allocating the scheduling requirement to each energy storage unit according to the initial state of charge of the battery pack in each energy storage unit comprises:
in the formula: p i (t): the power of the energy storage unit i at the moment t; p General assembly (t): scheduling requirements of the energy storage system at the time t; λ: energy storage charge-discharge state parameters; when P is General assembly (t)>λ ═ 1, P at 0 General (1) (t 1 )<λ is 0 when 0; SOC (system on chip) i (t): the initial charge state of the battery pack of the energy storage unit i at the moment t; i: the energy storage unit reference number i 1, 2, 3.. x.. y... n.
Preferably, the power angle value of the virtual synchronous machine corresponding to each energy storage unit is calculated according to the scheduling requirement allocated to each energy storage unit, as shown in the following formula:
in the formula: p i (t): the power of the energy storage unit i at the moment t; u: a terminal voltage of the virtual synchronous generator; e 0 : electromotive force of the virtual synchronous generator; x: deficiency of the heartReactance of a pseudo-synchronous generator; delta. for the preparation of a coating i_t : and (4) power angle of the energy storage unit i at the moment t.
Preferably, the merging the energy storage units, of which the power angle change is smaller than the threshold, into an energy storage subsystem includes:
calculating the absolute value of the difference of the power angle changes between the two energy storage units;
and if the absolute value is smaller than the threshold value, combining the two energy storage units into an energy storage subsystem and controlling the energy storage subsystem by using a virtual synchronous machine.
Preferably, the absolute value of the difference between the power angle changes of the two energy storage units is calculated according to the following formula:
A(t∈[t 1 ,t 2 ])＝|Δδ x_t -Δδ y_t |＜ε
in the formula: a: two energy storage units at t 1 Time to t 2 Absolute value of difference of maximum value of power angle change at time; delta delta x_t : energy storage unit x is at t 1 Time to t 2 The maximum value of the power angle change at the moment; delta delta y_t : energy storage unit y is at t 1 Time to t 2 The power angle at the moment changes by a maximum value.
Preferably, the energy storage unit is at t 1 Time to t 2 The maximum value of the power angle change at the moment is calculated according to the following formula:
in the formula:
energy storage unit i is at t 1 The power angle value at the moment;
energy storage unit i is at t 2 The power angle value at the moment; i: the energy storage unit is labeled i 1, 2, 3.. x.. y... n.
Preferably, the operation data of the energy storage subsystem includes active power, reactive power, voltage output by the energy storage converter and current output by the transformer, and are respectively calculated by the following formulas:
in the formula: p (t) m : active power of the energy storage subsystem m; active power; p (t) n : the active power of the energy storage unit n; l: the number of equivalent energy storage units;
in the formula: q (t) m : reactive power of the energy storage subsystem m; q (t) n : reactive power of the energy storage unit n;
in the formula: u (t) m : the voltage output by the energy storage converter corresponding to the energy storage subsystem m; u (t) n : the energy storage unit n corresponds to the voltage output by the energy storage converter;
in the formula: i (t) m : the current output by the transformer corresponding to the energy storage subsystem m; i (t) n : the energy storage unit n corresponds to the current output by the energy storage converter.
Preferably, the operation data of the energy storage subsystem further includes:
calculating the state of charge of the battery pack in the energy storage subsystem according to the following formula:
in the formula: s. the soc (t) m : the charge state of the energy storage subsystem m at the moment t; s. the soc (t) n : the charge state of an energy storage unit n in the energy storage subsystem at the time t; l: the number of equivalent energy storage units in the energy storage subsystem.
Preferably, the state of charge of the battery pack in each energy storage unit at the next time is calculated as follows:
in the formula: s. the soc (t + Δ t): the state of charge of the energy storage unit after the time delta t; Δ t: a time interval; s soc (t): the state of charge of the energy storage unit at time t; p (t) n : the active power of the energy storage unit n at the moment t; c: the battery capacity of the energy storage unit is kW.h.
Preferably, before calculating the state of charge of the battery pack in each energy storage unit at the next time, the method includes:
and acquiring the initial charge state of the battery pack in each energy storage unit.
Based on the same invention concept, the invention also provides a device for simulating the energy storage system based on the equivalent model, which comprises the following steps:
an acquisition module: the system is used for acquiring scheduling requirements, power generation data of a power grid and calculating the charge state of the battery pack in each energy storage unit at the next moment;
a calling module: and the system is used for substituting the scheduling requirement, the power generation data of the power grid and the charge state of the battery pack in each energy storage unit into a pre-constructed equivalent model for calculation to obtain the operation data of the energy storage subsystem until the simulation is finished.
Preferably, the apparatus further comprises:
a distribution module: the system comprises a plurality of energy storage units, a scheduling unit and a control unit, wherein the scheduling unit is used for distributing scheduling requirements to the energy storage units according to the initial charge states of battery packs in the energy storage units;
a calculation module: the virtual synchronous machine power angle value calculation module is used for calculating the power angle value of the virtual synchronous machine corresponding to each energy storage unit according to the scheduling requirement distributed to each energy storage unit;
a merging module: the energy storage units are used for combining the energy storage units with the power angle change smaller than a threshold value of the virtual synchronous machine into an energy storage subsystem;
an equivalence module: the method is used for performing equivalence calculation inside each energy storage subsystem; constructing a module: and the method is used for constructing an equivalence model based on the energy storage subsystem subjected to the equivalence calculation.
Compared with the closest prior art, the technical scheme provided by the invention has the following beneficial effects:
according to the technical scheme provided by the invention, the dispatching requirement and the power generation data of the power grid are collected, and the charge state of the battery pack in each energy storage unit at the next moment is calculated; and substituting the scheduling requirement, the power generation data of the power grid and the charge state of the battery pack in each energy storage unit into a pre-constructed equivalent model for calculation to obtain the operation data of the energy storage subsystem until the simulation is finished, and increasing the simulation speed through the equivalent model.
According to the technical scheme provided by the invention, the energy storage requirements are distributed to each energy storage unit according to the initial charge state of the battery pack in each energy storage unit; then calculating a power angle value of the virtual synchronous machine corresponding to each energy storage unit; merging the energy storage units with the power angle change of the virtual synchronous machine smaller than a threshold value into an energy storage subsystem; performing equivalence calculation inside each energy storage subsystem; and then, an equivalent model is constructed based on the energy storage subsystem subjected to equivalent calculation, so that the energy storage unit has a simple structure, and the calculated amount is reduced.
According to the technical scheme provided by the invention, the calculation parameters can be adjusted according to the actual condition of the energy storage power station so as to realize real-time simulation on the premise of stabilizing the energy storage system.
The technical scheme provided by the invention has certain expandability from the viewpoints of energy storage and new energy development, fully considers the characteristic of inconsistent working states of the energy storage converter and the battery pack thereof in the energy storage power station in the engineering practice, reduces the complexity of energy storage simulation calculation, and improves the calculation speed of the energy storage system simulation.
Drawings
FIG. 1 is a flow chart of the present invention for performing simulation based on an equivalent model;
FIG. 2 is a structural diagram of a large-scale battery energy storage power station controlled based on a virtual synchronous machine in the present embodiment;
fig. 3 is a schematic diagram of a power-angle relationship curve of the synchronous motor in this embodiment;
FIG. 4 is a simulation flowchart of the equivalent modeling method in this embodiment.
Detailed Description
For a better understanding of the present invention, reference is made to the following description taken in conjunction with the accompanying drawings and examples.
In the embodiment, the method and the device for simulating the energy storage system based on the equivalent model are provided, and based on a Virtual Synchronous Generator (VSG) technology, the grid-connected energy storage converter of the energy storage system can be controlled to simulate the operation characteristics of the synchronous generator to a certain extent, so that the grid-connected energy storage converter has excellent performance even exceeding that of the synchronous generator. On the premise that an energy storage system is divided into a plurality of energy storage units, the power of each energy storage unit is reasonably distributed, a virtual synchronous machine control mode is adopted, and the energy storage units with similar working states are subjected to equivalent calculation through a pre-established equivalent judgment standard, so that the simulation speed is increased.
Fig. 1 is a flow chart of the equivalent model-based simulation in this embodiment, and as shown in fig. 1, a flow of a method for performing simulation of an energy storage system based on an equivalent model is as follows:
step S101, collecting scheduling requirements, power grid power generation data and calculating the charge state of a battery pack in each energy storage unit at the next moment;
and S102, substituting the scheduling requirement, the power generation data of the power grid and the charge states of the battery packs in the energy storage units into a pre-constructed equivalent model for calculation to obtain the operation data of the energy storage subsystem until the simulation is finished.
In this embodiment, a process for constructing an equivalent model is provided, which includes:
distributing scheduling requirements to each energy storage unit according to the initial charge state of the battery pack in each energy storage unit;
calculating a power angle value of the virtual synchronous machine corresponding to each energy storage unit according to the scheduling requirements distributed to each energy storage unit;
merging the energy storage units with the power angle change smaller than a threshold value of the virtual synchronous machine into an energy storage subsystem;
performing equivalence calculation inside each energy storage subsystem;
and constructing an equivalence model based on the energy storage subsystem subjected to equivalence calculation.
Fig. 2 is a structural diagram of controlling a large-scale battery energy storage power station based on a virtual synchronizer, in this embodiment, an energy storage system is divided into N energy storage units by taking an energy storage converter as a unit, each energy storage unit includes an energy storage converter and a battery pack with different capacities, as shown in fig. 2, it can be seen that each energy storage unit belongs to a parallel structure, each energy storage unit in the whole system is controlled by a virtual synchronizer control mode, and each energy storage unit is connected with an alternating current bus through a transformer and is merged into a power grid.
Fig. 3 is a schematic diagram of a power angle relationship curve of a synchronous motor, and it can be seen that when power changes, the power angle of the virtual synchronous motor also changes correspondingly. Given active power Pslave P 1 Increase to P 2 At this time, the system switches from the original stable operation point a to the new stable operation point b. The change in power angle presents a repetitive ringing process represented in the power angle curve as shown in fig. 3.
In the present embodiment, a typical oscillation period is provided as δ 1 —δ 2 ，δ 2 —δ 3 ，δ 3 —δ 2 ，δ 2 —δ 1 These 4 intervals (respectively denoted as intervals 1, 2, 3, and 4) have different characteristics of power variation and power angle variation. From the physical point of view, when the input power is from P 1 Increase to P 2 When the angular velocity of the virtual rotor will increase, i.e. d ω/dt>0。
In the interval 1, since the virtual rotor angular speed of the VSG is greater than the angular speed of the power grid, i.e. ω > ω g, a larger rotor inertia is required to restrict the increase of the virtual rotor angular speed, so as to prevent a larger rotational speed overshoot caused by an excessively fast increase of the angular speed.
In the interval 2, the virtual rotor angular speed of the VSG is still greater than the angular speed of the power grid, but at this time, the virtual rotor angular speed of the VSG enters a deceleration state, that is, d ω/dt <0, and so on.
In the embodiment, the energy storage unit adopts a virtual synchronous machine control mode, a second-order model is considered to be adopted by a virtual synchronous machine model, and a second-order model of the synchronous motor is given by taking a rotating speed omega and a power angle delta of the generator as state variables according to the following formula.
Wherein J is moment of inertia; t is m And T e Mechanical torque and electromagnetic torque respectively; d is the damping coefficient corresponding to the damping torque from the mechanical friction, stator losses, excitation and damping windings.
Synchronous generator through mechanical torque T to prime mover m The control of the frequency regulator is used for regulating the output active power of the generator, and meanwhile, the frequency regulator is used for realizing the response to the frequency deviation of the power grid. By using the adjusting mode of the synchronous motor for reference, the T of the virtual synchronous machine m From each energy storage unit P i (t) and frequency ω together determine:
for electromagnetic torque T e Active power P actually output by the energy storage unit i And frequency, representing:
the rotational inertia J and the damping coefficient D reflecting the damping torque and frequency deviation are similar to the virtual synchronous machine definition in the general sense.
Because the energy storage system controlled by the virtual synchronizer has the moment of inertia J, the energy storage system is distributed to the storageActive power reference value P of energy unit i (t) and the actual power P i When the difference exists between the two, the change of power and frequency cannot be generated immediately, so that the stability of a power grid is facilitated. Meanwhile, because the active power reference value and the actual power are different at the same moment, the change of the virtual rotor rotating speed is equivalent to the differential adjustment of the oscillation attenuation, thereby causing the oscillation change of the power angle.
As shown in fig. 4, the specific steps of simulation by combining the construction of the equivalent model in this embodiment are as follows:
step 1) initializing parameters including a power angle of the virtual synchronous machine, initial active power of an energy storage unit, an energy storage unit SOC and the like. Adjusting model parameters according to actual conditions, namely adjusting the rotary inertia J and the damping coefficient D, wherein the purpose of adjustment is to ensure that each energy storage unit stably runs on the premise that the virtual synchronous machine is not overshot, and meanwhile, the energy storage unit can timely respond to the change of power requirements of the energy storage unit at the next moment;
step 2) calculating the total power which should be generated by the energy storage power station at the current moment according to the scheduling requirement and the photovoltaic/wind power real-time data, distributing the energy storage requirement to each energy storage unit according to the charge state of the battery pack in each energy storage unit, and calculating according to the following formula:
in the formula: p is i (t): the power of the energy storage unit i at the moment t; ptotal (t): scheduling requirements of the energy storage system at the time t; λ: energy storage charge-discharge state parameters; when P is total (t)>0 time λ ═ 1, Ptotal (t1)<λ is 0 when 0; SOC (system on chip) i (t): the initial charge state of the battery pack of the energy storage unit i at the moment t; i: the energy storage unit reference number i 1, 2, 3.. x.. y... n.
Step 3) calculating the power angle value of the virtual synchronous machine corresponding to the newly distributed power reference value of each energy storage unit at the current moment, as shown in the following formula:
in the formula: p i (t): the power of the energy storage unit i at the moment t; u: a terminal voltage of the virtual synchronous generator; e 0 : electromotive force of the virtual synchronous generator; x: a reactance of the virtual synchronous generator; delta i_t : and (4) power angle of the energy storage unit i at the moment t.
Calculating the absolute value of the difference of the power angle changes between the two energy storage units according to the following formula:
A(t∈[t 1 ,t 2 ])＝|Δδ x_t -Δδ y_t |＜ε
in the formula: a: two energy storage units at t 1 Time to t 2 Absolute value of difference of maximum value of power angle change at time; delta delta x_t : energy storage unit x is at t 1 Time to t 2 The maximum value of the power angle change at the moment; delta delta y_t : energy storage unit y is at t 1 Time to t 2 The power angle at the moment changes by a maximum value.
The energy storage unit at t is calculated according to the following formula 1 Time to t 2 Maximum power angle change at time:
in the formula:
energy storage unit i is at t 1 The power angle value at the moment;
energy storage unit i is at t 2 The power angle value at the moment; i: the energy storage unit reference number i 1, 2, 3.. x.. y... n.
And 4) comparing every two energy storage units according to an equivalence criterion, calculating the absolute value of the difference of power angle changes between the two energy storage units, finding out the energy storage units of which the absolute values are smaller than a preset threshold epsilon, and combining the two energy storage units into an energy storage subsystem and controlling the energy storage subsystem by using a virtual synchronizer.
And 5) if the energy storage units are combined, performing parameter integration on equivalent energy storage units, and calculating the operation data of the energy storage subsystems according to the equivalent energy storage units in each energy storage subsystem, wherein the operation data comprises: active power, reactive power, voltage output by the energy storage converter and current output by the transformer; otherwise step 6) is performed.
Respectively calculating the active power, the reactive power, the voltage output by the energy storage converter and the current output by the transformer of the energy storage subsystem according to the following formula:
in the formula: p (t) m : active power of the energy storage subsystem m; p (t) n : the active power of the energy storage unit n; l: the number of equivalent energy storage units;
in the formula: q (t) m : reactive power of the energy storage subsystem m; q (t) n : reactive power of the energy storage unit n;
in the formula: u (t) m : the voltage output by the energy storage converter corresponding to the energy storage subsystem m; u (t) n : the energy storage unit n corresponds to the voltage output by the energy storage converter;
in the formula: i (t) m : the current output by the transformer corresponding to the energy storage subsystem m; i (t) n : the energy storage unit n corresponds to the current output by the energy storage converter.
Calculating the state of charge of the battery pack in the energy storage subsystem according to the following formula:
in the formula: s soc (t) m : the state of charge of the energy storage subsystem m at the moment t; s soc (t) n : the charge state of an energy storage unit n in the energy storage subsystem at the moment t; l: the number of equivalent energy storage units in the energy storage subsystem.
And 6) calculating the SOC of the energy storage unit after the current moment is finished according to the power reference value of the energy storage unit, and simultaneously taking the power angle as an initial parameter calculated at the next moment and as an initial value of simulation at the next moment. Calculating the charge state of the energy storage unit at the next moment according to the charge state of the equivalent energy storage units in each energy storage subsystem, wherein the charge state is shown as the following formula:
in the formula: s soc (t + Δ t): the average value of the battery pack charge state after the energy storage unit is at delta t; s soc (t): the average value of the battery pack state of charge of the energy storage unit at the moment t; p (t) n : the active power of the energy storage unit n at the moment t; c: the battery capacity of the energy storage unit is kW.h.
And 7) continuously acquiring the scheduling requirements and power grid power generation data, taking the charge state of the battery pack in each energy storage unit at the next moment as an initial value, and substituting the initial value into an equivalent model to calculate until the simulation is finished.
Based on the same invention idea, this embodiment further provides a device for simulating an energy storage system based on an equivalent model, including:
an acquisition module: the system is used for acquiring scheduling requirements, power generation data of a power grid and calculating the charge state of a battery pack in each energy storage unit at the next moment;
a calling module: and the energy storage subsystem is used for substituting the scheduling requirement, the power generation data of the power grid and the charge state of the battery pack in each energy storage unit into a pre-constructed equivalent model for calculation to obtain the operation data of the energy storage subsystem until the simulation is finished.
Further, the apparatus further comprises:
a distribution module: the system comprises a plurality of energy storage units, a controller and a controller, wherein the energy storage units are used for storing the initial charge state of the battery pack in each energy storage unit;
a calculation module: the virtual synchronous machine power angle value calculation module is used for calculating the power angle value of the virtual synchronous machine corresponding to each energy storage unit according to the scheduling requirement distributed to each energy storage unit;
a merging module: the energy storage units are used for combining the energy storage units with the power angle change smaller than a threshold value of the virtual synchronous machine into an energy storage subsystem;
an equivalence module: the method is used for performing equivalence calculation inside each energy storage subsystem; constructing a module: and the method is used for constructing an equivalence model based on the energy storage subsystem subjected to the equivalence calculation. In an embodiment, the merging module includes:
and a calculation absolute value submodule: the absolute value of the difference of the power angle changes between the two energy storage units is calculated;
a judgment submodule: and if the absolute value is smaller than the threshold value, combining the two energy storage units into an energy storage subsystem and controlling the energy storage subsystem by using a virtual synchronous machine.
In an embodiment, the calculate absolute value submodule includes:
the first calculation unit: for calculating the absolute value of the difference between the power angle changes between the two energy storage units according to the following formula,
A(t∈[t 1 ,t 2 ])＝|Δδ x_t -Δδ y_t |＜ε
in the formula: a: two energy storage units at t 1 Time to t 2 Absolute value of difference of maximum value of power angle change at moment; delta delta x_t : energy storage unit x is at t 1 Time to t 2 The maximum value of the power angle change at the moment; delta delta y_t : energy storage unit y is at t 1 Time to t 2 The maximum value of the power angle change at the moment;
a second calculation unit: for calculating the energy storage unit at t as follows 1 Time to t 2 The maximum value of the power angle change at the moment,
in the formula:
energy storage unit i is at t 1 The power angle value at the moment;
energy storage unit i is at t 2 Work angle of time
A value; i: the energy storage unit is labeled i 1, 2, 3.. x.. y... n.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and so forth) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The present invention is not limited to the above embodiments, and any modifications, equivalent substitutions, improvements, etc. within the spirit and principle of the present invention are included in the scope of the claims of the present invention as filed.
Claims (6)
1. A method for simulating an energy storage system based on an equivalent model is characterized by comprising the following steps:
acquiring scheduling requirements, power generation data of a power grid and calculating the charge state of a battery pack in each energy storage unit at the next moment;
substituting the scheduling requirement, the power generation data of the power grid and the charge state of the battery pack in each energy storage unit into a pre-constructed equivalent model for calculation to obtain the operation data of the energy storage subsystem until the simulation is finished;
the construction of the equivalent model comprises the following steps:
distributing scheduling requirements to each energy storage unit according to the initial charge state of the battery pack in each energy storage unit;
calculating a power angle value of the virtual synchronous machine corresponding to each energy storage unit according to the scheduling requirements distributed to each energy storage unit;
merging the energy storage units with the power angle change of the virtual synchronous machine smaller than a threshold value into an energy storage subsystem;
performing equivalence calculation inside each energy storage subsystem;
constructing an equivalent model based on the energy storage subsystem subjected to the equivalent calculation;
the merging the energy storage units with the power angle variation smaller than the threshold value of the virtual synchronous machine into an energy storage subsystem includes:
calculating the absolute value of the difference of the power angle changes between the two energy storage units;
if the absolute value is smaller than the threshold value, combining the two energy storage units into an energy storage subsystem and controlling the energy storage subsystem by using a virtual synchronizer;
the absolute value of the difference between the power angle changes of the two energy storage units is calculated according to the following formula:
A(t∈[t 1 ,t 2 ])＝|Δδ x_t -Δδ y_t |＜ε
in the formula: a: two energy storage units at t 1 Time to t 2 Absolute value of difference of maximum value of power angle change at moment; delta delta x_t : energy storage unit x is at t 1 Time to t 2 The maximum value of the power angle change at the moment; delta delta y_t : energy storage unit y is at t 1 Time to t 2 The maximum value of the power angle change at the moment;
the energy storage unit is at t 1 Time to t 2 The maximum value of the power angle change at the moment is calculated according to the following formula:
in the formula:
energy storage unit i is at t 1 The power angle value at the moment;
energy storage unit i is at t 2 The power angle value at the moment; i: an energy storage unit index, i ═ 1, 2, 3.. x.. y... n;
the operation data of the energy storage subsystem comprises active power, reactive power, voltage output by the energy storage converter and current output by the transformer, and are respectively calculated through the following formulas:
in the formula: p (t) m : active power of the energy storage subsystem m; active power; p (t) n : the active power of the energy storage unit n; l: the number of equivalent energy storage units;
in the formula: q (t) m : reactive power of the energy storage subsystem m; q (t) n : reactive power of the energy storage unit n;
in the formula: u (t) m : the voltage output by the energy storage converter corresponding to the energy storage subsystem m; u (t) n : the energy storage unit n corresponds to the voltage output by the energy storage converter;
in the formula: i (t) m : the current output by the transformer corresponding to the energy storage subsystem m; i (t) n : the energy storage unit n corresponds to the current output by the energy storage converter;
further comprising:
calculating the state of charge of the battery pack in the energy storage subsystem according to the following formula:
in the formula: s soc (t) m : the state of charge of the energy storage subsystem m at the moment t;S soc (t) n : the charge state of an energy storage unit n in the energy storage subsystem at the moment t; l: the number of equivalent energy storage units in the energy storage subsystem.
2. The method of claim 1, wherein assigning scheduling requirements to each energy storage unit based on an initial state of charge of a battery pack in each energy storage unit comprises:
in the formula: p is i (t): the power of the energy storage unit i at the moment t; p General assembly (t): scheduling requirements of the energy storage system at the time t; λ: energy storage charge-discharge state parameters; when P is present General (1) (t)>λ ═ 1, P at 0 General (1) (t 1 )<λ is 0 at 0; SOC (system on chip) i (t): the initial charge state of the battery pack of the energy storage unit i at the moment t; i: the energy storage unit reference number i 1, 2, 3.. x.. y... n.
3. The method according to claim 1, wherein the power angle value of the virtual synchronous machine corresponding to each energy storage unit is calculated according to the scheduling requirement allocated to each energy storage unit, as shown in the following formula:
in the formula: p is i (t): the power of the energy storage unit i at the moment t; u: a terminal voltage of the virtual synchronous generator; e 0 : electromotive force of the virtual synchronous generator; x: a reactance of the virtual synchronous generator; delta i_t : and (4) the power angle of the energy storage unit i at the time t.
4. The method of claim 1, wherein the state of charge of the battery pack in each energy storage unit at the next time is calculated as follows:
in the formula: s. the soc (t + Δ t): the state of charge of the energy storage unit after the time delta t; Δ t: a time interval; s soc (t): the state of charge of the energy storage unit at time t; c: the battery capacity of the energy storage unit is kW.h.
5. The method of claim 1, wherein calculating the state of charge of the battery pack in each energy storage unit at the next time comprises:
and acquiring the initial charge state of the battery pack in each energy storage unit.
6. An apparatus for performing equivalence model-based simulation of an energy storage system, which implements an equivalence model-based simulation method for an energy storage system according to any one of claims 1 to 5, comprising:
an acquisition module: the system is used for acquiring scheduling requirements, power generation data of a power grid and calculating the charge state of a battery pack in each energy storage unit at the next moment;
a calling module: the system comprises a scheduling demand, a power grid power generation data and the state of charge of battery packs in energy storage units, and is used for substituting the scheduling demand, the power grid power generation data and the state of charge of the battery packs in the energy storage units into a pre-constructed equivalent model for calculation to obtain operation data of an energy storage subsystem until the simulation is finished;
further comprising:
a distribution module: the system comprises a plurality of energy storage units, a controller and a controller, wherein the energy storage units are used for storing the initial charge state of the battery pack in each energy storage unit;
a calculation module: the virtual synchronous machine power angle value calculation module is used for calculating the power angle value of the virtual synchronous machine corresponding to each energy storage unit according to the scheduling requirement distributed to each energy storage unit;
a merging module: the energy storage units are used for combining the energy storage units with the power angle change smaller than a threshold value into an energy storage subsystem;
an equivalence module: the method is used for performing equivalence calculation inside each energy storage subsystem;
constructing a module: and the method is used for constructing an equivalence model based on the energy storage subsystem subjected to the equivalence calculation.
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