CN116345484A - Droop control method for adaptive change rate of AC/DC hybrid micro-grid - Google Patents

Droop control method for adaptive change rate of AC/DC hybrid micro-grid Download PDF

Info

Publication number
CN116345484A
CN116345484A CN202310112579.XA CN202310112579A CN116345484A CN 116345484 A CN116345484 A CN 116345484A CN 202310112579 A CN202310112579 A CN 202310112579A CN 116345484 A CN116345484 A CN 116345484A
Authority
CN
China
Prior art keywords
change rate
change
value
rate
grid
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202310112579.XA
Other languages
Chinese (zh)
Inventor
杜燕
王鑫
杨向真
崇鹏宇
苏建徽
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hefei University of Technology
Original Assignee
Hefei University of Technology
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hefei University of Technology filed Critical Hefei University of Technology
Priority to CN202310112579.XA priority Critical patent/CN116345484A/en
Publication of CN116345484A publication Critical patent/CN116345484A/en
Pending legal-status Critical Current

Links

Images

Classifications

    • 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
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F17/00—Digital computing or data processing equipment or methods, specially adapted for specific functions
    • G06F17/10—Complex mathematical operations
    • G06F17/11—Complex mathematical operations for solving equations, e.g. nonlinear equations, general mathematical optimization problems
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F17/00—Digital computing or data processing equipment or methods, specially adapted for specific functions
    • G06F17/10—Complex mathematical operations
    • G06F17/18—Complex mathematical operations for evaluating statistical data, e.g. average values, frequency distributions, probability functions, regression analysis
    • 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
    • H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
    • 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
    • H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
    • H02J2003/365—Reducing harmonics or oscillations in HVDC

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Mathematical Physics (AREA)
  • Data Mining & Analysis (AREA)
  • Theoretical Computer Science (AREA)
  • Computational Mathematics (AREA)
  • Mathematical Analysis (AREA)
  • Mathematical Optimization (AREA)
  • Pure & Applied Mathematics (AREA)
  • General Engineering & Computer Science (AREA)
  • Algebra (AREA)
  • Databases & Information Systems (AREA)
  • Software Systems (AREA)
  • Operations Research (AREA)
  • Power Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Bioinformatics & Cheminformatics (AREA)
  • Bioinformatics & Computational Biology (AREA)
  • Evolutionary Biology (AREA)
  • Probability & Statistics with Applications (AREA)
  • Supply And Distribution Of Alternating Current (AREA)

Abstract

The invention discloses a droop control method of an adaptive change rate of an alternating current-direct current hybrid micro-grid, and relates to the field of control of interconnected converters in the alternating current-direct current hybrid micro-grid; the method comprises the steps of firstly, respectively normalizing alternating current frequency, direct current voltage and corresponding change rate, constructing an equation by utilizing normalized values of actual output power, alternating current frequency, direct current voltage and corresponding change rate of the interconnected converter, obtaining reference power of the interconnected converter, establishing a self-adaptive rule of a change rate droop coefficient, and designing the change rate droop coefficient of each stage according to parameter characteristics of a system. The invention can regulate and control the change rate of the two ends of the sub-network, balance the normalized value of the change rate of the alternating current frequency and the direct current voltage, and improve the dynamic and steady-state performance of the alternating current-direct current sub-network.

Description

Droop control method for adaptive change rate of AC/DC hybrid micro-grid
Technical Field
The invention relates to the technical field of converter control in a hybrid micro-grid, in particular to a self-adaptive change rate droop control method of an alternating current-direct current hybrid micro-grid, which is suitable for improving the dynamic and steady-state performance of an alternating current-direct current sub-grid.
Background
Along with the continuous development of new energy technology, the advantages that the AC/DC hybrid micro-grid is independent and autonomous, integrates various types of distributed generators, has various load types, can be connected to the energy storage system efficiently and compatibly, and the like are also widely paid attention. The interconnected converter is used as a bridge for connecting the AC/DC sub-network, bears the power interaction of the two sub-networks, and plays an important role in the voltage and frequency stabilization of the AC/DC bus and the improvement of the system power quality.
The control strategy of the interconnection converter generally adopts a double-droop control method, realizes that the frequency of an alternating current bus is equal to the normalized value of the voltage of a direct current bus by utilizing the droop characteristic of an alternating current/direct current sub-network, and distributes load power according to the respective capacity at two ends of the corresponding alternating current/direct current sub-network. The droop control is mainly aimed at controlling the steady state of direct-current voltage and alternating-current frequency, dynamic control on the voltage and the frequency is lacked, the inertia of a hybrid micro-grid formed by networking the power electronic inverter is small, and micro sources cannot provide inertia support for an alternating-current sub-network and a direct-current sub-network by adopting droop control, so that the problems of bus voltage of the direct-current sub-network, bus voltage of the alternating-current sub-network and frequency stability are serious. At present, most of scholars aim at the problem that bus voltage and frequency instability easily occur in a power grid running in an island when the output of a distributed power supply is insufficient and the load fluctuates in the moment of inertia of a micro-grid, and the dynamic performance is improved by controlling an interconnection converter. Along with the wide application of the virtual synchronous motor technology, the AC/DC sub-network has certain inertia and can support the dynamic requirement when the sub-network operates independently. However, after the ac/dc sub-networks are interconnected and run, the dynamic characteristics of the sub-networks are also coupled through the ILC, so that the dynamic performance of the ac/dc hybrid micro-grid is degraded, especially when the inertia of the two sub-networks is not matched, the problems of oscillation and even instability of the dc voltage and the ac frequency, and out-of-limit oscillation, frequency change rate, voltage change rate and the like of the power transmitted by the interconnection converter occur.
Disclosure of Invention
The invention aims to solve the defects of the prior art, and provides a droop control method of an adaptive change rate of an AC/DC hybrid micro-grid, so as to realize transient power and steady power distribution of a two-terminal grid, balance normalization values of an AC frequency and a DC voltage and normalization values of respective corresponding change rates, improve transient steady state characteristics of the AC/DC hybrid micro-grid, and effectively avoid power transmission oscillation and out-of-range change rates of the voltage and the frequency.
The invention adopts the following technical scheme for solving the technical problems:
the invention relates to a droop control method of an adaptive change rate of an AC/DC hybrid micro-grid, which is characterized by comprising the following steps:
1) Establishing a normalization equation of alternating current frequency and direct current voltage and respective corresponding change rates;
2) Normalizing the alternating current frequency and the direct current voltage obtained by sampling to obtain a normalized value of the alternating current frequency, a normalized value of the direct current voltage, a normalized value of the alternating current frequency change rate and a normalized value of the direct current voltage change rate;
3) Constructing an active power reference equation by utilizing the actual output power of the interconnected converter, the alternating frequency and the direct voltage obtained by sampling and the normalization value of the respective corresponding change rate;
4) Establishing an adaptive rule of a change rate droop coefficient of an active power reference equation;
5) According to a state matrix of the AC/DC hybrid micro-grid, designing a change rate droop coefficient for enabling the AC/DC hybrid micro-grid to have an optimal damping ratio in a self-adaptive rule;
6) And designing the maximum value of the droop coefficient of the change rate in the self-adaptive rule according to the power transmission limit constraint of the interconnected converter.
The droop control method of the self-adaptive change rate of the AC/DC hybrid micro-grid is also characterized in that in the step 1, an AC frequency, a DC voltage and a corresponding change rate normalization equation are respectively established through a formula (1) and a formula (2):
Figure SMS_1
Figure SMS_2
omega in the formula (1) and the formula (2) max 、ω min Respectively the frequency omega of the alternating current bus ac Maximum and minimum of (2); u (u) max 、u min Respectively the DC bus voltage u dc Maximum value, minimum value, omega N 、u N Respectively the frequency omega of the alternating current bus ac And a DC bus voltage u dc Nominal value of omega ac.pu 、u dc.pu Omega respectively ac 、u dc Is normalized by the value of (2); (dω) ac /dt) p.u 、(du dc /dt) p.u Respectively the frequency change rate dω ac Rate of change du of voltage/dt dc Normalized value of/dt; (dω) ac /dt) limit 、(du dc /dt) limit Respectively the frequency change rate dω ac Rate of change du of voltage/dt dc Maximum limit value of/dt.
In step 2, the ac frequency and the dc voltage obtained by sampling are normalized by the formulas (3) and (4), respectively:
Figure SMS_3
Figure SMS_4
omega in the formula (3) and the formula (4) acs 、u dcs Ac frequency and dc voltage, ω, obtained by sampling, respectively acs.pu 、u dcs.pu Omega respectively acs 、u dcs Is normalized by the value of (2); dω acs /dt、du dcs The ratio of the alternating current frequency change rate and the direct current voltage change rate obtained by sampling are respectively represented by (dω) acs /dt) p.u 、(du dcs /dt) p.u Dω, respectively acs /dt、du dcs Normalized value of/dt.
In the step 3, an active power reference equation is constructed by using the formula (5):
Figure SMS_5
in the formula (5), the amino acid sequence of the compound,
Figure SMS_6
representing the active reference power, P, of the interconnected current transformer ILC ILC Representing the actual output active power, k, of the interconnected converter ILC s 、K d Respectively a steady state droop coefficient and a change rate droop coefficient of the interconnection converter ILC; k (k) ac 、k dc Equivalent droop coefficients for ac and dc subnetworks, respectively.
The self-adaptive rule of the step 4 is as follows:
when the change rate is normalized
Figure SMS_7
And->
Figure SMS_8
When the operation margin epsilon is smaller than the operation margin epsilon, the change rate sagging coefficient K of the interconnection converter d Take steady state value K * The AC/DC hybrid micro-grid has the optimal damping ratio;
when the load disturbance on the AC/DC bus leads to the normalization value of the change rate
Figure SMS_9
Or->
Figure SMS_10
The instantaneous rate of change droop factor K is greater than the motion margin ε d Take the maximum value K max Subsequently K d Fast tuning to have optimal damping ratio for ac/dc hybrid micro-gridSteady state value K * The method comprises the steps of carrying out a first treatment on the surface of the And obtaining an adaptive rate of change droop coefficient K by using the formula (6) d ：
Figure SMS_11
In the formula (6), epsilon is an action margin, K * To enable the AC/DC hybrid micro-grid to have a steady state value of an optimal damping ratio, K max For the rate of change sag factor K d Maximum value that can be taken; t is t s For the rate of change sag factor K d From K max Change to K * When the change rate is normalized
Figure SMS_12
Or->
Figure SMS_13
When the motion margin epsilon is larger than the motion margin epsilon, t s Starting timing when the normalized value of the change rate +.>
Figure SMS_14
And->
Figure SMS_15
When the motion margin epsilon is smaller, t is smaller than s Setting 0; m is an adjustment K d Coefficient of variation speed, K d From K max Adjusted to K * +10％*(K max -K * ) Is equal to the set transition period deltat and +.>
Figure SMS_16
Ensuring steady state value K in step 5 * The value of (1) enables the AC/DC hybrid micro-grid to obtain the optimal damping ratio, namely K * The value of (2) is such that the characteristic root lambda determining the damping ratio of the system in the system state matrix A satisfies the formula (7):
Figure SMS_17
in the formula (8), ζ is the damping ratio of the system, and λ is the characteristic root determining the damping ratio of the system in the state matrix a.
In step 6, the droop coefficient K of the change rate in the adaptive rule is designed according to the power transmission limit constraint of the interconnected converters by using the formula (9) d Maximum value K that can be taken max ：
Figure SMS_18
In the formula (8), P ILC,max Represented as the maximum power value that the interconnection inverter ILC can take.
The electronic equipment comprises a memory and a processor, wherein the memory is used for storing a program for supporting the processor to execute any droop control method of the adaptive change rate of the AC/DC hybrid micro-grid, and the processor is configured to execute the program stored in the memory.
The invention relates to a computer readable storage medium, wherein a computer program is stored on the computer readable storage medium, and is characterized in that the computer program is executed by a processor to execute the step of the droop control method of the adaptive change rate of the AC/DC hybrid micro-grid.
Compared with the prior art, the invention has the beneficial effects that:
1. on the basis of steady-state power distribution, the invention introduces normalization constraint for the alternating current frequency change rate and the direct current voltage change rate, and effectively avoids the problems of power transmission oscillation, direct current bus voltage and alternating current bus frequency change rate out-of-range and the like.
2. The invention reasonably selects the droop coefficient of the change rate at each stage by carrying out self-adaptive control on the droop coefficient of the change rate, thereby ensuring the dynamic characteristic of the system and the transient power distribution of the AC/DC sub-network.
Drawings
FIG. 1 is a diagram of an interconnection converter topology and control;
FIG. 2 is a graph of the adaptive rate-of-change droop control of the AC/DC hybrid micro-grid of the invention;
FIG. 3 is an island HMG system topology on a simulink platform;
FIG. 4 is a graph of DC bus voltage, AC bus frequency, and ILC delivered power under control of ILC using only steady state power distribution;
FIG. 5 is a graph of DC bus voltage versus AC bus frequency per unit for ILC using only steady state power distribution control;
FIG. 6 is a graph of per unit of DC voltage change rate and AC frequency change rate under adaptive change rate droop control of an AC/DC hybrid micro-grid;
FIG. 7 is a graph of DC voltage, AC frequency per unit and ILC delivered power under adaptive rate-of-change droop control for an AC/DC hybrid microgrid;
fig. 8 is a graph of per unit value of the dc voltage change rate and the ac frequency change rate under the adaptive change rate droop control of the ac-dc hybrid micro-grid.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention are described in further detail below with reference to the accompanying drawings:
the control structure of the ILC shown in fig. 1 includes active loop, reactive loop and current inner loop control, and the reactive reference power of the interconnected converters takes 0 in view of only active power interaction between ac and dc subnets. The ac-dc hybrid microgrid adaptive rate-of-change droop control in fig. 2 generates the active reference power in fig. 1.
In this embodiment, a droop control method for adaptive rate of change of an ac/dc hybrid micro-grid is implemented by constructing a comprehensive transient and steady state characteristic equation and combining adaptive rate of change droop coefficients, so as to implement transient power and steady state power allocation of two sub-networks, and includes the following steps:
step 1), establishing a normalization equation of alternating current frequency and direct current voltage and respective corresponding change rates;
in specific implementation, an alternating frequency, a direct voltage and a corresponding change rate normalization equation are respectively established through the formula (1) and the formula (2):
Figure SMS_19
Figure SMS_20
omega in the formula (1) and the formula (2) max 、ω min Respectively the frequency omega of the alternating current bus ac Maximum and minimum of (2); u (u) max 、u min Respectively the DC bus voltage u dc Maximum value, minimum value, omega N 、u N Respectively the frequency omega of the alternating current bus ac And a DC bus voltage u dc Nominal value of omega ac.pu 、u dc.pu Omega respectively ac 、u dc Is normalized by the value of (2); (dω) ac /dt) p.u 、(du dc /dt) p.u Respectively the frequency change rate dω ac Rate of change du of voltage/dt dc Normalized value of/dt; (dω) ac /dt) limit 、(du dc /dt) limit Respectively the frequency change rate dω ac Rate of change du of voltage/dt dc Maximum limit value of/dt. Omega max 、ω min 、u max 、u min 、(dω ac /dt) limit 、(du dc /dt) limit Is a fixed parameter, and is taken from the power grid operation control specification.
Step 2) normalizing the alternating current frequency and the direct current voltage obtained by sampling to obtain a normalized value of the alternating current frequency, a normalized value of the direct current voltage, a normalized value of the alternating current frequency change rate and a normalized value of the direct current voltage change rate;
in step 2, the ac frequency and the dc voltage obtained by sampling are normalized by the formulas (3) and (4), respectively:
Figure SMS_21
Figure SMS_22
omega in the formula (3) and the formula (4) acs 、u dcs Ac frequency and dc voltage, ω, obtained by sampling, respectively acs.pu 、u dcs.pu Omega respectively acs 、u dcs Is normalized by the value of (2); dω acs /dt、du dcs The ratio of the alternating current frequency change rate and the direct current voltage change rate obtained by sampling are respectively represented by (dω) acs /dt) p.u 、(du dcs /dt) p.u Dω, respectively acs /dt、du dcs Normalized value of/dt.
Step 3) constructing an active power reference equation by utilizing the actual output power of the interconnected converters, the alternating frequency and the direct voltage obtained by sampling and the normalized value of the corresponding change rate;
in the step 3, an active power reference equation is constructed by using the formula (5):
Figure SMS_23
in the formula (5), the amino acid sequence of the compound,
Figure SMS_24
representing the active reference power, P, of the interconnected current transformer ILC ILC Representing the actual output active power, k, of the interconnected converter ILC s 、K d Respectively a steady state droop coefficient and a change rate droop coefficient of the interconnection converter ILC; k (k) ac 、k dc Equivalent droop coefficients for ac and dc subnetworks, respectively.
Step 4) establishing an adaptive rule of a change rate droop coefficient of an active power reference equation;
when the AC/DC independently operates, the bus is at t 0 The loading process may be according to (dω ac /dt) p.u 、(du dc /dt) p.u The trend of (c) can be divided into 2 stages.
Stage I (t) 0 -t 0+ ): with load disturbance, | (du) dc /dt) p.u |、|(dω ac /dt) p.u Increase, t 0+ The moment reaches a maximum. Since the maximum value of RoCoX occurs at t 0+ Time of day, thus phase I goalIs that the adaptive rate of change droop control scheme to be proposed can be well balanced (du dc /dt) p.u I and I (dω) ac /dt) p.u Magnitude of i. At this time ω ac.pu 、u dc.pu The deviation is close to 0, and the equation (5) is used for balancing omega ac.pu 、u dc.pu Is smaller, mainly by (du) dc /dt) p.u |、|(dω ac /dt) p.u The deviation is dominant, and the maximum K can be used d Make | (du) dc /dt) p.u |、|(dω ac /dt) p.u The values are closest.
Stage II (t) 0+ -t 1 )：t 0+ After the moment, | (du) dc /dt) p.u Sum (dω) ac /dt) p.u The value of i gradually decreases to 0, ω ac.pu 、u dc.pu The deviation of (2) gradually increases. At this stage, due to the maximum K d Will decrease the HMG stability and thus require the selection of an appropriate K d Avoiding voltage and frequency oscillation, ensuring the HMG system to have better damping ratio and avoiding increasing the adjustment time.
Thus, the adaptation law of step 4 is established as: when the change rate is normalized
Figure SMS_25
And->
Figure SMS_26
When the operation margin epsilon is smaller than the operation margin epsilon, the change rate sagging coefficient K of the interconnection converter d Take steady state value K * The AC/DC hybrid micro-grid has the optimal damping ratio; when the load disturbance on the AC/DC bus leads to the normalized value of the change rate>
Figure SMS_27
Or->
Figure SMS_28
The instantaneous rate of change droop factor K is greater than the motion margin ε d Take the maximum value K max Subsequently K d Quickly adjusting to a steady-state value K for enabling an alternating-current/direct-current hybrid micro-grid to have an optimal damping ratio * The method comprises the steps of carrying out a first treatment on the surface of the And obtaining an adaptive rate of change droop coefficient K by using the formula (6) d ：
Figure SMS_29
In the formula (6), epsilon is an action margin, K * To enable the AC/DC hybrid micro-grid to have a steady state value of an optimal damping ratio, K max For the rate of change sag factor K d Maximum value that can be taken; t is t s For the rate of change sag factor K d From K max Change to K * When the change rate is normalized
Figure SMS_30
Figure SMS_31
Figure SMS_32
When the motion margin epsilon is larger than the motion margin epsilon, t s Starting timing when the normalized value of the change rate +.>
Figure SMS_33
And->
Figure SMS_34
When the motion margin epsilon is smaller, t is smaller than s Setting 0; m is an adjustment K d Coefficient of variation speed, K d From K max Adjusted to K * +10％*(K max -K * ) Is equal to the set transition period deltat and +.>
Figure SMS_35
The small signal state space model of the AC/DC hybrid micro-grid is established as shown in (7.1):
Figure SMS_36
the state variable is x= [ Δω ] ac ,Δu dc ,Δω ac ,Δu dcs ,ΔP ILC ] T The method comprises the steps of carrying out a first treatment on the surface of the Input variable u= [ Δp ac_load ,ΔP dc_load ] T ；
Figure SMS_37
Figure SMS_38
Wherein delta is the small signal quantity of the corresponding variable, J ac 、J dc Expressed as equivalent inertia, ω, of the ac sub-network, dc sub-network, respectively α 、ω β 、ω c The cut-off frequencies of equivalent filters of the alternating current sub-network, the direct current sub-network and the interconnection converter are respectively set. The dynamic performance of the AC/DC hybrid micro-grid can be evaluated by using the characteristic root of the state matrix A.
Step 5) designing a droop coefficient of the change rate of the optimal damping ratio of the AC/DC hybrid micro-grid in a self-adaptive rule according to the state matrix of the AC/DC hybrid micro-grid;
ensuring steady state value K in step 5 * The value of (1) enables the AC/DC hybrid micro-grid to obtain the optimal damping ratio, namely K * The value of (2) is such that the characteristic root lambda determining the damping ratio of the system in the system state matrix A satisfies the formula (7):
Figure SMS_39
in the formula (7), xi is the damping ratio of the system, and lambda is the characteristic root for determining the damping ratio of the system in the state matrix A.
And 6) designing the maximum value of the droop coefficient of the change rate in the self-adaptive rule according to the power transmission limit constraint of the interconnected converters.
In step 6, the droop coefficient K of the change rate in the adaptive rule is designed according to the power transmission limit constraint of the interconnected converters by using the formula (8) d Maximum value K that can be taken max ：
Figure SMS_40
In the formula (9), P ILC,max Represented as the maximum power value that the interconnection inverter ILC can take.
In this embodiment, an electronic device includes a memory for storing a program for supporting the processor to execute the droop control method of the ac/dc hybrid micro-grid adaptive rate of change described above, and a processor configured to execute the program stored in the memory.
In this embodiment, a computer readable storage medium stores a computer program, which when executed by a processor, performs the steps of the droop control method of the adaptive rate of change of the ac/dc hybrid micro-grid.
In order to verify the effectiveness of the adaptive change rate droop control of the direct-current hybrid micro-grid submitted by the invention, an island HMG system model is built on a Matlab/Simulink platform, and simulation parameters are shown in table 1.
Table 1 simulation parameters
Figure SMS_41
The system topology is shown in fig. 3. The direct current sub-network consists of two DC/DC converters and is controlled by a virtual capacitor; the alternating current sub-network consists of two DC/AC inverters, VSG control is adopted, the interconnection converter ILC adopts a control mode shown in figure 1, the interconnection converter comprises an active loop, a reactive loop and a current inner loop, the specific control mode of the active loop is shown in figure 2, and the current inner loop adopts decoupling control.
In order to verify the effectiveness of the adaptive change rate droop control of the direct-current hybrid micro-grid submitted by the invention, 2 control modes are set for simulation comparison: 1) ILC employs only the traditional dual droop control method, only for steady state power allocation. At 1s, the ac bus is loaded with 5kw and the dc bus is loaded with 15kw. 2) The ILC employs adaptive rate of change droop control to constrain ac bus frequency and dc bus voltage while distributing steady state power. At 1s, the ac bus is loaded with 5kw and the dc bus is loaded with 15kw.
As shown in fig. 4, the ILC only adopts steady-state power distribution control, and the interconnection converter transmits 5kw of power support to the dc side, so that the load power borne by the two-terminal network is equal to 10kw. As shown in fig. 4 and 5, in this control method, the ac bus frequency, the dc bus voltage, and the ILC transmission power oscillate, and stability of the system is affected.
Under the adaptive change rate droop control of the direct current sub-network submitted by the invention, as shown in fig. 7 and 8, the interconnected converter transmits 5kw of power support to the direct current side, and the two sub-networks bear the same load power, which is 10kw, so that the distribution of steady-state power in the traditional double droop control method is realized. In fig. 7 and 8, the ac bus frequency, the dc bus voltage, and the ILC transmission power do not oscillate, and the system has good dynamic characteristics. Further, as shown in fig. 6, | (du) dc /dt) p.u I and I (dω) ac /dt) p.u The maximum values of the I are the same, the dynamic characteristics of the sub-networks are mutually supported, and the system has stronger stability.
The method of the invention makes up the defect of constraint on the dynamic characteristics of the system in the control of the existing interconnected converter, so that the system can accurately transmit power by utilizing ILC when reaching steady state, and the AC/DC sub-network supports the load together according to the respective capacity; and the dynamic process of the alternating current bus frequency and the direct current bus voltage during load abrupt change can be optimized. The effectiveness of the method is verified through simulation.

Claims (9)

1. The droop control method for the adaptive change rate of the AC/DC hybrid micro-grid is characterized by comprising the following steps of:
1) Establishing a normalization equation of alternating current frequency and direct current voltage and respective corresponding change rates;
2) Normalizing the alternating current frequency and the direct current voltage obtained by sampling to obtain a normalized value of the alternating current frequency, a normalized value of the direct current voltage, a normalized value of the alternating current frequency change rate and a normalized value of the direct current voltage change rate;
3) Constructing an active power reference equation by utilizing the actual output power of the interconnected converter, the alternating frequency and the direct voltage obtained by sampling and the normalization value of the respective corresponding change rate;
4) Establishing an adaptive rule of a change rate droop coefficient of an active power reference equation;
5) According to a state matrix of the AC/DC hybrid micro-grid, designing a change rate droop coefficient for enabling the AC/DC hybrid micro-grid to have an optimal damping ratio in a self-adaptive rule;
6) And designing the maximum value of the droop coefficient of the change rate in the self-adaptive rule according to the power transmission limit constraint of the interconnected converter.
2. The droop control method of the adaptive rate of change of the ac/dc hybrid micro-grid according to claim 1, wherein in the step 1, an ac frequency, a dc voltage and a corresponding rate of change normalization equation are respectively established by equation (1) and equation (2):
Figure FDA0004077366260000011
Figure FDA0004077366260000012
omega in the formula (1) and the formula (2) max 、ω min Respectively the frequency omega of the alternating current bus ac Maximum and minimum of (2); u (u) max 、u min Respectively the DC bus voltage u dc Maximum value, minimum value, omega N 、u N Respectively the frequency omega of the alternating current bus ac And a DC bus voltage u dc Nominal value of omega ac.pu 、u dc.pu Omega respectively ac 、u dc Is normalized by the value of (2); (dω) ac /dt) p.u 、(du dc /dt) p.u Respectively the frequency change rate dω ac Rate of change du of voltage/dt dc Normalized value of/dt; (dω) ac /dt) limit 、(du dc /dt) limit Respectively the frequency change rate dω ac Rate of change du of voltage/dt dc Maximum limit value of/dt.
3. The droop control method of the adaptive change rate of the ac/dc hybrid micro-grid according to claim 2, wherein in step 2, the ac frequency and the dc voltage obtained by sampling are normalized by equation (3) and equation (4), respectively:
Figure FDA0004077366260000013
Figure FDA0004077366260000021
omega in the formula (3) and the formula (4) acs 、u dcs Ac frequency and dc voltage, ω, obtained by sampling, respectively acs.pu 、u dcs.pu Omega respectively acs 、u dcs Is normalized by the value of (2); dω acs /dt、du dcs The ratio of the alternating current frequency change rate and the direct current voltage change rate obtained by sampling are respectively represented by (dω) acs /dt) p.u 、(du dcs /dt) p.u Dω, respectively acs /dt、du dcs Normalized value of/dt.
4. The droop control method of the adaptive rate of change of the ac/dc hybrid micro-grid according to claim 3, wherein in step 3, an active power reference equation is constructed by using equation (5):
Figure FDA0004077366260000022
in the formula (5), the amino acid sequence of the compound,
Figure FDA0004077366260000023
representing the active reference power, P, of the interconnected current transformer ILC ILC Representing the actual output of the interconnected converter ILCPower, k s 、K d Respectively a steady state droop coefficient and a change rate droop coefficient of the interconnection converter ILC; k (k) ac 、k dc Equivalent droop coefficients for ac and dc subnetworks, respectively.
5. The droop control method of the adaptive rate of change of the ac/dc hybrid micro-grid according to claim 4, wherein the adaptive rule of step 4 is:
when the change rate is normalized
Figure FDA0004077366260000024
And->
Figure FDA0004077366260000025
When the operation margin epsilon is smaller than the operation margin epsilon, the change rate sagging coefficient K of the interconnection converter d Take steady state value K * The AC/DC hybrid micro-grid has the optimal damping ratio;
when the load disturbance on the AC/DC bus leads to the normalization value of the change rate
Figure FDA0004077366260000026
Or->
Figure FDA0004077366260000027
The instantaneous rate of change droop factor K is greater than the motion margin ε d Take the maximum value K max Subsequently K d Quickly adjusting to a steady-state value K for enabling an alternating-current/direct-current hybrid micro-grid to have an optimal damping ratio * The method comprises the steps of carrying out a first treatment on the surface of the And obtaining an adaptive rate of change droop coefficient K by using the formula (6) d ：
Figure FDA0004077366260000028
In the formula (6), epsilon is an action margin, K * To enable the AC/DC hybrid micro-grid to have a steady state value of an optimal damping ratio, K max For the rate of change sag factor K d Maximum value that can be taken;t s for the rate of change sag factor K d From K max Change to K * When the change rate is normalized
Figure FDA0004077366260000031
Or->
Figure FDA0004077366260000032
When the motion margin epsilon is larger than the motion margin epsilon, t s Starting to count time when the change rate is normalized
Figure FDA0004077366260000033
And->
Figure FDA0004077366260000034
When the motion margin epsilon is smaller, t is smaller than s Setting 0; m is an adjustment K d Coefficient of variation speed, K d From K max Adjusted to K * +10％*(K max -K * ) Is equal to the set transition period deltat and +.>
Figure FDA0004077366260000035
6. The droop control method for adaptive rate of change of an ac/dc hybrid micro-grid according to claim 5, wherein a steady state value K is ensured in step 5 * The value of (1) enables the AC/DC hybrid micro-grid to obtain the optimal damping ratio, namely K * The value of (2) is such that the characteristic root lambda determining the damping ratio of the system in the system state matrix A satisfies the formula (7):
Figure FDA0004077366260000036
in the formula (8), ζ is the damping ratio of the system, and λ is the characteristic root determining the damping ratio of the system in the state matrix a.
7. The intersection of claim 5The droop control method of the self-adaptive change rate of the direct-current hybrid micro-grid is characterized in that in the step 6, the droop coefficient K of the change rate in the self-adaptive rule is designed by utilizing a formula (9) according to the power transmission limit constraint of the interconnected converters d Maximum value K that can be taken max ：
Figure FDA0004077366260000037
In the formula (8), P ILC,max Represented as the maximum power value that the interconnection inverter ILC can take.
8. An electronic device comprising a memory and a processor, wherein the memory is configured to store a program for supporting the processor to execute the droop control method of the ac-dc hybrid micro-grid adaptive rate of change according to any one of claims 1-7, the processor being configured to execute the program stored in the memory.
9. A computer readable storage medium having a computer program stored thereon, wherein the computer program when executed by a processor performs the steps of the droop control method of the ac/dc hybrid micro-grid adaptive rate of change of any one of claims 1-7.
CN202310112579.XA 2023-02-14 2023-02-14 Droop control method for adaptive change rate of AC/DC hybrid micro-grid Pending CN116345484A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202310112579.XA CN116345484A (en) 2023-02-14 2023-02-14 Droop control method for adaptive change rate of AC/DC hybrid micro-grid

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202310112579.XA CN116345484A (en) 2023-02-14 2023-02-14 Droop control method for adaptive change rate of AC/DC hybrid micro-grid

Publications (1)

Publication Number Publication Date
CN116345484A true CN116345484A (en) 2023-06-27

Family

ID=86876529

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202310112579.XA Pending CN116345484A (en) 2023-02-14 2023-02-14 Droop control method for adaptive change rate of AC/DC hybrid micro-grid

Country Status (1)

Country Link
CN (1) CN116345484A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117856267A (en) * 2024-03-07 2024-04-09 上海融和元储能源有限公司 Isolated network system control strategy and system for disturbance rejection optimization processing from data source

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117856267A (en) * 2024-03-07 2024-04-09 上海融和元储能源有限公司 Isolated network system control strategy and system for disturbance rejection optimization processing from data source

Similar Documents

Publication Publication Date Title
CN106410849B (en) Microgrid inverter balance control method based on virtual synchronous generator
CN112467784B (en) Control method for adaptive virtual synchronous machine of hybrid microgrid converter
CN104242717B (en) Self adaptation based on virtual synchronous machine output impedance adjustment
CN104485689B (en) Droop control method based on adaptive model switching
CN114884125B (en) High-stability control method of LCL type grid-connected inversion system under weak current network
CN109980908B (en) Method for suppressing multi-inverter parallel harmonic under distributed control
CN109038642B (en) Self-energy-storage multi-terminal flexible-straight system control method and device
CN108448629B (en) Multi-inverter parallel resonance suppression method and device based on virtual impedance
CN110620399B (en) Inverter parallel control method and system based on robust residual generator
CN115085242A (en) Hybrid energy storage VSG self-adaptive virtual damping parameter setting method
CN116345484A (en) Droop control method for adaptive change rate of AC/DC hybrid micro-grid
Wu et al. A novel optimisation method for the design of LCL filters for three-phase grid-tied inverters
CN111817327A (en) H-bridge cascaded grid-connected energy storage system SOC balance control method
CN110970893A (en) Method for adaptively optimizing and regulating network inertia level based on active support type VSC
CN115864520A (en) Control method and system for accessing hybrid power grid based on high-proportion photovoltaic energy
Lin et al. Comparative analysis on the stability mechanism of droop control and VID control in DC microgrid
CN111555295B (en) Online coordination control method for multiple reactive power compensation devices in regional power grid
Ren et al. A virtual inertial control strategy for bidirectional interface converters in hybrid microgrid
CN113193569B (en) Capacitance energy control method with short-term frequency support and direct-current side oscillation suppression function
Zhou et al. Sub-synchronous damping by battery storage system in grid forming control mode
CN114597975A (en) Power distribution method and control equipment for parallel system
CN113241766A (en) Transformation ratio combined type current harmonic treatment method for three-phase four-wire grid-connected inverter
Zhang et al. Influence of control parameters on synchronization stability of virtual synchronous generator
Zhang et al. Mitigating disturbance in harmonic voltage using grid-side current feedback for grid-connected LCL-filtered inverter
CN114938006B (en) Virtual inertia-based power grid frequency control method and system

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination