Summary of the invention
In view of this, it is an object of the invention to propose a kind of direct-current grid steady-state performance analysis based on energy-storage system
Method, the elimination of the negative resistance character of realization constant power load that can be convenient and practical, and additional cost will not be caused, compared with
It is easy to accomplish.
Based on a kind of above-mentioned purpose direct-current grid steady-state performance analysis method based on energy-storage system provided by the invention,
Include:
Characteristic based on DC micro power grid system establishes the energy-storage system in DC micro power grid system in charge mode respectively
Under mixed potential function model and discharge mode under mixed potential function model;
Mixed potential function model and stability theorem based on building carry out steady-state performance analysis respectively, obtain energy storage
System in charging mode with the stability condition under discharge mode;
According to the obtained stability condition, by adjusting the parameter setting of energy-storage system, and then DC micro-electric is controlled
Net system stable operation.
Optionally, the mixed potential function model of the energy-storage system established in DC micro power grid system in charging mode
And the step of mixed potential function model under discharge mode further include:
Under charge mode, according to the definition and model parameter of mixed potential function theory, electric current potential function and electricity are obtained
Press potential function;
According to the model parameter of mixed potential function model and the characteristic of micro-grid system, obtains electric current and be respectively required for voltage
The condition for consistence to be met;
In discharge mode, using mode same as charge mode, electric current potential function, voltage potential under discharge mode are obtained
Function and mutually in requisition for satisfaction condition for consistence.
Optionally, the step of progress steady-state performance analysis further include:
Under charge mode, mixed potential function model and corresponding electric current potential function and voltage potential function based on building,
Two minimal eigenvalues relevant to system stability are derived by by stability theorem;
The condition met is needed according to described two minimal eigenvalues, obtains the stability of energy-storage system in charging mode
Condition;
In discharge mode, the stability condition of energy-storage system in discharge mode is obtained in the same way.
Optionally, the mixed potential function model of the energy-storage system in charging mode are as follows:
The mixed potential function model of the energy-storage system in discharge mode are as follows:
Wherein, i is the electric current by bus filter inductance;V is bus both ends of filter capacitor voltage;R0For equivalent internal resistance;P0
For bearing power;Pb1Power to charge the battery;Pb2For battery discharge power;VsFor busbar voltage;P (i, v) is mixing gesture
Function.
Optionally, under charge mode, the electric current potential function and voltage potential function are respectively as follows:
Electric current and voltage are respectively necessary for the condition for consistence met are as follows:
Wherein, A (i), B (v) are respectively electric current potential function and voltage potential function;L is bus filter inductance;C is bus filter
Wave capacitor;
Under discharge mode, the electric current potential function and voltage potential function are respectively as follows:
Mutually in requisition for the condition for consistence of satisfaction are as follows:
Optionally, matrix relevant to system stability is respectively as follows:
L-1/2Aii(i)L-1/2;
C-1/2Bvv(v)C-1/2;Wherein, Aii、BvvRespectively second order local derviation and voltage potential function of the electric current potential function to electric current i
To the second order local derviation of voltage v;
Under charge mode, two obtained minimal eigenvalues are respectively as follows:
Wherein, Pb1Power to charge the battery;
According to stability theorem, for the stability of safeguards system, minimal eigenvalue needs to meet:
μ1+μ2> 0;
It brings parameter into, obtains the stability condition of energy-storage system in charging mode are as follows:
Under discharge mode, two minimal eigenvalues are obtained in the same way and are respectively as follows:
Wherein, Pb2For battery discharge power;
It brings parameter into, obtains the stability condition of energy-storage system in discharge mode are as follows:
From the above it can be seen that the direct-current grid steady-state performance analysis side provided by the invention based on energy-storage system
Method is by reasonably controlling the energy storage section in system, so that be not necessarily under conditions of increasing any equipment, it can be effective
Eliminate the negative resistance character of constant power load.Specifically, the application analysis method by building micro-grid system charging and
Then energy function model under both of which of discharging carries out steady-state performance analysis by stability theorem, is charged and put
The quantitative restrictive condition of energy-storage system power and constant power load power under electric both of which, finally by guarantee isolated operation
The condition of the safe and stable operation of direct current micro-grid system, the parameter setting of corresponding regulating system, so that system always belongs to surely
Determine operating status.Therefore, the herein described direct-current grid steady-state performance analysis method based on energy-storage system can not only be square
Just the elimination of the negative resistance character of practical realization constant power load, and additional cost will not be caused, it is relatively easy to realize.
Specific embodiment
To make the objectives, technical solutions, and advantages of the present invention clearer, below in conjunction with specific embodiment, and reference
Attached drawing, the present invention is described in more detail.
It should be noted that all statements for using " first " and " second " are for differentiation two in the embodiment of the present invention
The non-equal entity of a same names or non-equal parameter, it is seen that " first " " second " only for the convenience of statement, does not answer
It is interpreted as the restriction to the embodiment of the present invention, subsequent embodiment no longer illustrates this one by one.
Be directed to the method for the negative resistance character of current common elimination constant power load there are the problem of, the present application
People discovery, in fact, the energy-storage system of accumulator in parallel with constant power load due to can between " recharge-discharge " state arbitrarily
Switching, operating mode is flexible, if controlling energy-storage system the negative resistance character for being rationally not only able to eliminate constant power load,
It will not influence the normal working performance of load simultaneously.In addition, such analysis method not will increase any hardware device, it is only necessary to
Control algolithm is improved, it is convenient and practical, it is easy to accomplish.
It is the direct-current grid steady-state performance analysis method provided by the invention based on energy-storage system referring to shown in Fig. 2
The flow diagram of one embodiment.The micro-capacitance sensor steady-state performance analysis method based on energy-storage system includes:
Step 101, based on the characteristic of DC micro power grid system, the energy-storage system established in DC micro power grid system respectively exists
Mixed potential function model under charge mode and the mixed potential function model under discharge mode;Namely it is being filled according to energy-storage system
Under two kinds of different working conditions of power mode and discharge mode, the energy function model namely mixed potential function of system are constructed respectively
Model so that energy-storage system is equivalent to load under charge mode, and is equivalent to current source portion in discharge mode.
Optionally, the mixed potential function model of the energy-storage system established in DC micro power grid system in charging mode
And the step of mixed potential function model under discharge mode further include:
Under charge mode, according to the definition and model parameter of mixed potential function model, electric current potential function and electricity are obtained
Press potential function;
According to the model parameter of mixed potential function model and the characteristic of micro-grid system, obtains electric current and be respectively required for voltage
The condition for consistence to be met;
In discharge mode, using mode same as charge mode, electric current potential function, voltage potential under discharge mode are obtained
Function and mutually in requisition for satisfaction condition for consistence.
In this way, can judge whether the mixed potential function model of building is protected with true system structure by condition for consistence
It holds unanimously, namely whether the model of building is accurate.
Step 102, mixed potential function model and stability theorem based on building carry out steady-state performance analysis respectively,
Obtain energy-storage system in charging mode with the stability condition under discharge mode;Namely pass through the mixed potential function mould to building
Type carries out stability analysis, so that only needing to meet accordingly stability condition can be so that system, which is in, stablizes shape
State.
Specifically, the step of progress steady-state performance analysis further include:
Under charge mode, mixed potential function model and corresponding electric current potential function and voltage potential function based on building,
Two minimal eigenvalues relevant to system stability are derived by by stability theorem;
The condition met is needed according to described two minimal eigenvalues, obtains the stability of energy-storage system in charging mode
Condition;
In discharge mode, the stability condition of energy-storage system in discharge mode is obtained in the same way.
Step 103, it according to the obtained stability condition, by adjusting the parameter setting of energy-storage system, and then controls
DC micro power grid system stable operation.That is, the corresponding parameter of setting system is reversely gone by stability condition, so that being
System meets stability condition always, namely always belongs to steady operational status.
As can be seen from the above embodiments, the herein described direct-current grid steady-state performance analysis method based on energy-storage system is logical
It crosses and the energy storage section in system is reasonably controlled, so that can be effectively eliminated without under conditions of increasing any equipment
The negative resistance character of constant power load.Specifically, the application analysis method is being charged and discharged by constructing micro-grid system
Then energy function model under both of which carries out stability analysis by stability theorem, obtain being charged and discharged two kinds
The quantitative restrictive condition of energy-storage system power and constant power load power under mode, it is micro- finally by the direct current for ensureing isolated operation
The condition of the safe and stable operation of net system, the parameter setting of corresponding regulating system, so that system always belongs to stable operation
State.Therefore, the herein described direct-current grid steady-state performance analysis method based on energy-storage system can not only be convenient and practical
Realization constant power load negative resistance character elimination, and additional cost will not be caused, be relatively easy to realize.
In some optional embodiments of the application, the direct-current grid steady-state performance analysis side based on energy-storage system
Method includes:
(1) energy-storage units of DC micro power grid system and the working characteristics of constant power load under island mode are analyzed.
In the DC micro power grid system of isolated operation, there are two types of working conditions for batteries to store energy unit: working as generated output
When greater than bearing power, energy-storage system works in charged state;When generated output is less than bearing power, energy-storage system work exists
Discharge condition.Energy-storage system works in different conditions, and different characteristics can be presented, and needs using different equivalent models.Charge shape
Under state, if charging current given value changes, actual charge current can also change therewith, battery and bi-directional DC-DC
The characteristic of load is presented in the energy-storage system of converter composition, and in modeling, disposable load model is carried out equivalent.Electric power storage tank discharge work
It is usually constant-current discharge as state, therefore current source characteristic is presented in battery and DC-DC converter, controlled electricity can be used in modeling
Stream source carries out equivalent.Constant power load then uses Ideal Nonlinear model: Po=constant=VoIoTo indicate.Simplified isolated island fortune
The lower DC micro power grid system topological structure of row is as shown in figure 3, include DC bus, equivalent internal resistance R0, LC filter and permanent function
Rate load and energy-storage system of accumulator.
(2) it is based on system structure shown in Fig. 3, establishes system respectively in energy storage charge and discharge using mixed potential function theory
Mixed potential function model under mode.
Specifically: firstly, being derived by the mixed potential function model of DC micro power grid system under charge mode:
According to model parameter shown in mixed potential function definition and formula (1), voltage potential function A (i) and voltage can be respectively obtained
Potential function B (v) is respectively as follows:
According to formula (1) model parameter and system shown in Figure 3 structure, under charge mode, electric current and voltage meet respectively:
Formula (4) shows that model parameter and system structure are consistent, it can thus be appreciated that the model of charged state shown in formula (1) is joined
Number is correct.
Similarly, the mixed potential function model of system under discharge mode can be obtained according to mixed potential function theory:
According to model parameter shown in mixed potential function definition and formula (5), the current potential letter under discharge mode can be respectively obtained
Number A (i) and voltage potential function B (v), are respectively as follows:
According to formula (5) model parameter and system shown in Figure 3 structure, under discharge mode, electric current and voltage meet respectively:
Formula (8) shows that model parameter and system structure are consistent, it can thus be appreciated that the model of discharge condition shown in formula (5) is joined
Number is correct.
(3) stability analysis is carried out based on mixed potential function model parameter
According to mixed potential function stability theorem, need respectively to the DC micro power grid system of charging, electric discharge two states into
Row stability analysis.
Under energy-storage system charged state, according to stability theorem, matrix L need to be derived by-1/2Aii(i)L-1/2Minimum it is special
Value indicative μ1And Matrix C-1/2Bvv(v)C-1/2Minimal eigenvalue μ2, according to mixed potential function model parameter shown in formula (1), can obtain:
According to mixed potential function stability theorem, in order to which safeguards system is stablized, μ1、μ2It should meet:
μ1+μ2> 0 (11)
It can then be released according to formula (9), (10) and (11):
Criterion shown in formula (12) shows in the DC micro power grid system of isolated operation, when constant power load power and electric power storage
The sum of the charge power in pond is less than R0Cv2When/L, system being capable of stable operation.That is, for safeguards system stable operation,
The sum of the maximum power to charge to constant power load maximum power and energy-storage system gives restrictive condition.
Similarly, the system performance under energy storage system discharges state can be analyzed, according to model parameter shown in formula (5), can be obtained:
For safeguards system stable operation, μ need to be met1+μ2> 0, then:
Criterion shown in formula (15) shows in the DC micro power grid system of isolated operation, when constant power load power subtracts storage
The difference of battery discharge power is less than R0Cv2When/L, system being capable of stable operation.Contrast (12) and formula (15) are it is found that in order to ensure
The size of system stable operation, the operating mode and constant power load power of battery is closely related.When constant power load power
When smaller, no matter battery is charged or discharged, system all can stable operation;When constant power load power is larger, battery
In heavy-current discharge state, it can also ensure that parameter meets (15), to maintain system stable operation.That is, electric discharge shape
The energy-storage system of accumulator of state improves micro-grid system and is capable of providing to the maximum power of constant power load, increases system
Stability range, safeguards system safe and stable operation.
Further, in order to verify herein described analysis method the advantages of, additionally provides stability in some embodiments
The verification experimental verification of criterion.It is specific as follows:
For the stability criteria that verification expression (12) and formula (15) obtain, simplification system as shown in Figure 4 is built and has carried out
Verification experimental verification.Wherein, system busbar voltage is set as 380V, and equivalent internal resistance is 0.02 Ω, and the voltage of battery group is 150V, electricity
Sense is 1mH, capacitor 1mF.Energy-storage system includes DC-DC reversible transducer and battery.Constant power load is by closed-loop control
Buck converter and resistance are constituted, voltage sensor therein constantly detection resistance voltage, and feed back to controller, and controller is logical
Overdrive circuit controls IGBT module movement, to ensure that resistance both end voltage is constant, disregards circuit loss, load resistance is
The device of power, the constant function for also meaning that Buck converter and absorbing from DC side of voltage are uniquely consumed in Buck converter
Rate is constant, to realize constant power load characteristic.
System parameter under battery charging mode is analyzed first, according to formula (12), the system of can be obtained is capable of providing
Battery charge power and the sum of constant power load power maximum value meet:
Battery charging current is 5A, charge power 750W, according to formula (16) it is found that the invariable power that system can undertake
Maximum load power meets:
P0< 2138W (17)
Constant power load initial power is 500W, carries out two groups of parameter comparisons, parameter 1: constant power load power is from 500W
Step is to 1500W;Parameter 2: constant power load power rises to 4000W from 500W.Wherein, shown in 1 data symbols of parameter box-like (12)
Stability criterion, and 2 data of parameter are unsatisfactory for formula (12).Fig. 5 gives busbar voltage and constant power load in situation shown in parameter 1
Current waveform figure, when the power of constant power load is from 500W step to 1500W, busbar voltage is able to maintain stabilization.Fig. 6 gives
The current waveform figure for having gone out busbar voltage and constant power load in situation shown in parameter 2, when the power of constant power load is from 500W
When rising to 4000W, busbar voltage oscillation.
Comparison diagram 5 and Fig. 6 can be clearly seen, and when parameter meeting formula (12), system being capable of stable operation;Conversely, working as
When parameter is not inconsistent box-like (12), system generates concussion.Thus energy-storage system charged state stability inferior shown in formula (12) is demonstrated
The accuracy of criterion.
Then energy storage system discharges state is analyzed, the initial power of constant power load is 500W, the function after step
Rate is 5000W.For the correctness of verification expression (15), two groups of parameter comparisons, parameter 1: energy storage system discharges electric current are equally carried out
For 20A;Parameter 2: energy storage system discharges electric current 5A.Wherein, stability criterion shown in 1 data symbols of parameter box-like (15), and the number of parameter 2
Meet formula (15) according to when constant power load power is 500W, is unsatisfactory for formula (15) when constant power load power is 5000W.Figure
7 give the current waveform figure of busbar voltage and constant power load in situation shown in parameter 1, when constant power load power from
When 500W step is to 5000W, busbar voltage is able to maintain stabilization.Fig. 8 gives busbar voltage and permanent function in situation shown in parameter 2
The current waveform figure of rate load, when the power of constant power load rises to 5000W from 500W, there is oscillatory instability in busbar voltage
The phenomenon that.
Comparison diagram 7 and Fig. 8, the stability criterion formula (15) under energy storage system discharges mode are verified.Comparison diagram 6, Fig. 7
With Fig. 8 it is found that can by increase energy-storage system of accumulator discharge power come increase system the power with constant power load,
The stability range of raising system, the energy-storage system of accumulator for also demonstrating discharge condition improves micro-grid system really to be mentioned
The maximum power for supplying constant power load, increases the stability range of system, safeguards system safe and stable operation.
It should be understood by those ordinary skilled in the art that: the discussion of any of the above embodiment is exemplary only, not
It is intended to imply that the scope of the present disclosure (including claim) is limited to these examples;Under thinking of the invention, above embodiments
Or can also be combined between the technical characteristic in different embodiments, step can be realized with random order, and be existed such as
Many other variations of the upper different aspect of the invention, for simplicity, they are not provided in details.
In addition, to simplify explanation and discussing, and in order not to obscure the invention, it can in provided attached drawing
It is connect with showing or can not show with the well known power ground of integrated circuit (IC) chip and other components.Furthermore, it is possible to
Device is shown in block diagram form, to avoid obscuring the invention, and this has also contemplated following facts, i.e., about this
The details of the embodiment of a little block diagram arrangements be height depend on will implementing platform of the invention (that is, these details should
It is completely within the scope of the understanding of those skilled in the art).Elaborating that detail (for example, circuit) is of the invention to describe
In the case where exemplary embodiment, it will be apparent to those skilled in the art that can be in these no details
In the case where or implement the present invention in the case that these details change.Therefore, these descriptions should be considered as explanation
Property rather than it is restrictive.
Although having been incorporated with specific embodiments of the present invention, invention has been described, according to retouching for front
It states, many replacements of these embodiments, modifications and variations will be apparent for those of ordinary skills.Example
Such as, discussed embodiment can be used in other memory architectures (for example, dynamic ram (DRAM)).
The embodiment of the present invention be intended to cover fall into all such replacements within the broad range of appended claims,
Modifications and variations.Therefore, all within the spirits and principles of the present invention, any omission, modification, equivalent replacement, the improvement made
Deng should all be included in the protection scope of the present invention.