CN116470529A - Frequency modulation control parameter setting method and device for distributed photovoltaic power generation system - Google Patents
Frequency modulation control parameter setting method and device for distributed photovoltaic power generation system Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
- H02J3/241—The oscillation concerning frequency
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/381—Dispersed generators
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
- H02J3/466—Scheduling the operation of the generators, e.g. connecting or disconnecting generators to meet a given demand
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
- H02J3/48—Controlling the sharing of the in-phase component
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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]
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
- H02J2300/20—The dispersed energy generation being of renewable origin
- H02J2300/22—The renewable source being solar energy
- H02J2300/24—The renewable source being solar energy of photovoltaic origin
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/56—Power conversion systems, e.g. maximum power point trackers
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Abstract
The invention discloses a frequency modulation control parameter setting method and device for a distributed photovoltaic power generation system. The method of the invention comprises the following steps: the distributed photovoltaic power generation system boosts voltage through a direct current converter, controls direct current voltage through a capacitor, and is connected with a grid through an alternating current-direct current converter, so that spare allowance of equipment is reserved to provide frequency modulation supporting capability during power generation; the AC/DC converter of the photovoltaic power generation system is controlled by adopting a constant DC voltage; the direct current converter of the photovoltaic power generation system adopts constant power control, and a feedback branch circuit of frequency deviation is introduced to the direct current converter; determining the capacity of a single photovoltaic power generation system for frequency modulation support of a power system by utilizing the spare margin of equipment, and then designing an initial value of an active power control parameter; and simulating the distributed photovoltaic power generation system with the initial value of the active power control parameter to obtain the active power control parameter with minimum line loss. The invention realizes the tuning of the frequency modulation control parameters of the minimum line loss of the equipment and ensures the stable operation of the power system.
Description
Technical Field
The invention relates to the technical field of distributed photovoltaic power generation systems, in particular to a frequency modulation control parameter setting method and device for a distributed photovoltaic power generation system.
Background
Large-scale photovoltaic power generation is usually a process of converting direct current generated by a solar power generation system into alternating current, and mainly works by using a grid-connected inverter. The photovoltaic grid-connected power generation system mainly comprises a large grid-connected power generation station and a distributed small grid-connected power generation system, wherein the photovoltaic grid-connected power generation system is used for completing conversion at the power generation station, is suitable for large-scale power generation stations in China, is widely applied to residential buildings, and is suitable for integration of photovoltaic buildings. The photovoltaic power generation grid-connected system does not need the energy storage and energy release processes, is beneficial to reducing energy loss and improves the power utilization efficiency. The large-scale photovoltaic power generation has the following advantages: the large-scale photovoltaic power generation can improve the utilization efficiency of electric energy, and is beneficial to reducing the loss condition of the electric energy; solar energy is a clean energy source, and compared with other forms, the solar energy resource is beneficial to reducing environmental pollution. Meanwhile, after the high-permeability distributed power supply is connected into the active power distribution network, the dispatching operation mode of the power distribution network is changed significantly, and the power dispatching strategy, the power trading mode and the transmission and distribution interaction mode of the active power distribution network are different from those of the traditional power distribution network greatly. Under new situations and new environments, the optimization scheduling technology of the active power distribution network under the high-permeability distributed power supply access is researched, and the method has important significance for improving new energy consumption and improving the safety and economic operation capability of the power distribution network.
Today, large-scale photovoltaic systems are introduced, such that a large number of power electronics change the natural modes of existing power systems, such that the power quality is reduced. The number and the scale of the photovoltaic generator set systems are different, so that the whole frame of the power system is changed to a certain extent, the control of the tide distribution is more difficult, and the voltage quality of the power distribution network is greatly influenced. The damping and inertia of the high-proportion new energy power system are greatly changed, and the influence on the power grid is more remarkable. When a large number of photovoltaic power generation replaces synchronous machines, the power electronic characteristics of the power system are obvious, the rotation reserve capacity and the moment of inertia of the power system are relatively reduced, the inertia level of the system is reduced, the frequency response characteristic is deteriorated, the capacity of the system for resisting the power difference is weakened, and the pressure of safe and stable operation of the power system is increased.
There are many methods for providing frequency support to ac systems, and more, besides from the perspective of flow control, frequency-droop control is adopted, or equivalent inertia and damping of ac systems are improved; meanwhile, the research of the frequency supporting capability of the existing distributed power supply mainly seeks breakthrough in the equipment, and the research of the coordination and matching frequency modulation control capability among single machines is ignored.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a tuning method and a tuning device for tuning frequency modulation control parameters in a coordinated manner on the basis of a distributed photovoltaic power generation system taking an adjustment control power instruction as a working principle, so as to realize tuning of the frequency modulation control parameters of the minimum line loss of equipment under the constraint conditions of self equipment and the constraint of a power grid frequency guide rule, and ensure the stable operation of a power system.
For this purpose, the invention adopts a technical scheme that: the frequency modulation control parameter setting method of the distributed photovoltaic power generation system comprises the following steps:
step 1), boosting by a direct current converter, controlling direct current voltage by using a capacitor, and then connecting the power to a grid by an alternating current-direct current converter, wherein during power generation, spare allowance of equipment is reserved to provide frequency modulation supporting capacity; the AC/DC converter of the photovoltaic power generation system is controlled by adopting a constant DC voltage; the direct current converter of the photovoltaic power generation system adopts constant power control, and a feedback branch circuit of frequency deviation is introduced to the direct current converter;
step 2), determining the frequency modulation supporting capacity of a single photovoltaic power generation system in the distributed photovoltaic power generation system by using the spare allowance of the equipment; after the frequency modulation supporting capacity of a single photovoltaic power generation system to the power system is calculated, the initial value design of the active power control parameter of the single photovoltaic system in the distributed photovoltaic power generation system is carried out;
and 3) carrying out simulation on the distributed photovoltaic power generation system by taking the initial value of the active power control parameter to obtain the active power control parameter with the minimum line loss.
The invention is based on the existing frequency modulation strategy regulated by the active power instruction, and the photovoltaic power generation system is additionally provided with a branch of frequency information on the power instruction to control the direct current converter so as to realize the frequency support of the photovoltaic power generation system.
Further, in step 2), the photovoltaic power generation system adopts a frequency modulation strategy adjusted based on the active power instruction: inputting an active power adjustment instruction to a single photovoltaic power generation system, and leading out a feedback branch controlled by stable frequency deviation delta f;
under grid disturbance, the distributed photovoltaic power generation system provides active power support for the power distribution network, and steady-state frequency deviation needs to meet the constraint of a grid frequency guide rule:
Δf≤Δf max
wherein Δf max Maximum steady-state frequency deviation allowed for the distribution network;
in the ith photovoltaic power generation system, the active power control parameter of the stable frequency deviation delta f control feedback branch is K i The method comprises the steps of carrying out a first treatment on the surface of the Taking into account the active power control parameter K i The value needs to meet the self standby allowance of the photovoltaic power generation system, the regulating capacity needs to meet the rated active power of which the steady-state output is smaller than or equal to eta times according to the self situation and the actual demand of the equipment, and the constraint conditions are as follows:
Δf max ·K i ≤ηP PVi
wherein P is pvi Rated active power of the ith photovoltaic power generation system; η is the duty ratio of the spare margin of the photovoltaic power generation system.
Further, in step 2), the active power control parameter K i The initial value of (1) is taken by the spare margin of the device itself to provide half of the maximum output.
Further, step 3) performs simulation, which is divided into two types:
first, if the frequency modulation effect reaches a predetermined value, K is determined at that time i The value is the initial value;
second, if the frequency modulation effect does not reach the predetermined value, Δf is set according to the obtained Δf comparison max Obtaining the power delta P required by the system frequency modulation reaching the expected value, and proportionally increasing the active power control parameter K i Obtaining new reference value, re-simulating until the frequency modulation effect reaches the expected value, and obtaining K at the moment i The value is taken as an initial value.
Still further, for the frequency modulation capability of each photovoltaic power generation system of the optimal distributed photovoltaic power generation system, obtaining an active power control parameter under the condition of minimum line loss of the photovoltaic power generation grid-connected system, wherein the optimization constraint conditions are as follows:
ΔP total (S) Representing the total active power, ΔP, required to be provided by the distributed photovoltaic power generation system frequency support i And the active power output of the frequency support of the ith photovoltaic power generation system is represented.
The invention adopts another technical scheme that: frequency modulation control parameter setting device of distributed photovoltaic power generation system, it includes:
photovoltaic power generation system control unit: the distributed photovoltaic power generation system boosts voltage through a direct current converter, controls direct current voltage through a capacitor, and is connected with a grid through an alternating current-direct current converter, so that spare allowance of equipment is reserved to provide frequency modulation supporting capability during power generation; the AC/DC converter of the photovoltaic power generation system is controlled by adopting a constant DC voltage; the direct current converter of the photovoltaic power generation system adopts constant power control, and a feedback branch circuit of frequency deviation is introduced to the direct current converter;
power system frequency modulation support determination capability unit: determining the frequency modulation supporting capacity of a single photovoltaic power generation system in the distributed photovoltaic power generation system by using the spare allowance of the equipment;
active power control parameter initial value design unit: after the frequency modulation supporting capacity of a single photovoltaic power generation system to the power system is calculated, the initial value design of the active power control parameter of the single photovoltaic system in the distributed photovoltaic power generation system is carried out;
active power control parameter acquisition unit: and simulating the distributed photovoltaic power generation system with the initial value of the active power control parameter to obtain the active power control parameter with minimum line loss.
The invention has the beneficial effects that: the invention adds the constraint of the power grid frequency guide rule and the constraint of the standby margin of the equipment on the basis of considering the frequency modulation support of the system provided by the equipment, adjusts the active power control parameters of the photovoltaic power generation system, enhances the stability of the power system, has simple structure and convenient calculation, and has universality.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings may be obtained according to the drawings without inventive effort for a person skilled in the art.
FIG. 1 is a control block diagram of a prior art distributed photovoltaic grid-connected system;
FIG. 2 is a flow chart of a tuning control parameter method for a distributed photovoltaic power generation system according to the present invention;
FIG. 3 is a schematic diagram showing that the initial value of the active power control parameter meets the system frequency modulation requirement;
fig. 4 is a schematic diagram showing that the initial value of the active power control parameter does not meet the frequency modulation requirement of the system.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. All other embodiments, which can be made by one of ordinary skill in the art without inventive faculty, are intended to be within the scope of the present invention, based on the embodiments of the present invention.
Example 1
The embodiment is a tuning method for frequency modulation control parameters of a distributed photovoltaic power generation system, comprising the following steps:
a. referring to fig. 1, the invention performs parameter tuning based on a power instruction adjustment mode based on an active-frequency control strategy of a grid-connected photovoltaic power generation system. The photovoltaic power generation grid-connected system consists of a photovoltaic panel, a DC/DC converter, a DC/AC converter and a power grid. The DC/AC converter of the distributed photovoltaic power generation system adopts constant direct current voltage control, and the DC/DC converter of the single photovoltaic power generation system adopts constant power control, so that a frequency deviation feedback branch is introduced.
b. Referring to fig. 2, a flow chart of a tuning control parameter setting method for a distributed photovoltaic power generation system is shown. When the photovoltaic power generation system is disturbed, unbalanced power is generated, and the system needs to be supported by the distributed photovoltaic power generation system in frequency.
According to the method, parameter setting of frequency modulation control under the minimum line loss of the distributed equipment is considered, and constraint conditions of standby margin of the equipment and a power grid frequency guide rule are added.
Constraint conditions
1) Constraints for stable operation of the device itself
In the event of a frequency disturbance, the active power support provided by a single device to the distribution network cannot exceed the device's own reserve margin (η represents the duty cycle of the device's own reserve margin).
Δf max ·K i ≤ηP PVi (1)
Wherein: p (P) PVi Is rated active power, delta f of the ith photovoltaic power generation system max For maximum frequency deviation under constraint of power grid frequency guide rule, K i Is an active power control parameter.
2) Constraint of grid frequency guidelines
Under grid disturbance, the distributed equipment supports active power provided for the power distribution network, and steady-state frequency deviation needs to meet the constraint of a grid frequency guide rule:
Δf≤Δf max (2)
where Δf is the stable frequency deviation.
In order to obtain the optimal distribution of the frequency modulation capacity of each monomer of the distributed photovoltaic power generation system, obtaining the control parameters under the condition of minimum line loss of the photovoltaic power generation grid-connected system, the optimization constraint conditions are as follows:
ΔP total (S) Representing the total active power, ΔP, required to be provided by the distributed photovoltaic power generation system frequency support i And the active power output of the frequency support of the ith photovoltaic power generation system is shown.
The active power control parameter K provided by each photovoltaic power generation system in the distributed photovoltaic power generation system can be obtained through constraint conditions i 。
The distributed photovoltaic power generation grid-connected system shown in fig. 1 is exemplified by adopting a frequency modulation strategy based on active power instruction adjustment, a DC/DC converter of the photovoltaic power generation system is controlled by adopting constant power, and a frequency deviation feedback branch is introduced into the DC/DC converter, so that the effect of the method is illustrated.
Because the default parameters entered can obtain two results, the simulation situation is analyzed by the two results.
Case one: the frequency modulation effect reaches a preset value, at the moment, K i The values are initial values, table 1 represents the simulation design parameters of the simulink of MATLAB, f 0 Rated frequency for steady state operation of the system; h is the inertial time constant of the synchronous machine; p (P) L Maximum disturbance power which can occur to the power distribution network system; p (P) PVi Rated active power of the ith photovoltaic power generation system; p (P) base Rated power of the synchronous machine; Δf max Maximum steady-state frequency deviation allowed for the distribution network; z is the line impedance of a single photovoltaic.
The frequency response effect obtained by simulation analysis is shown in fig. 3. At this time, the initial value K can be obtained according to the formulas (1) and (2) 1 ＝166MW/Hz，K 2 =83 MW/Hz. From the simulated frequency response waveform, Δf at this time can be seen 1 =0.28 Hz, meeting the expected value, line loss P L1 ＝3.1583MW，P L2 0.7896MW, bus loss P L = 3.9479MW; then obtaining new gain parameter K through optimization constraint 1 ＝83MW/Hz，K 2 =166 MW/Hz, line loss P L1 ＝3.0576MW，P L2 0.8411MW, bus loss P L = 3.8987MW. The line losses are shown in table 2 below. The table shows that the optimized line loss is minimum, the obtained frequency change rate is within the allowable maximum frequency change of the power distribution network, and the simulation result is consistent with the theoretical control parameter setting flow.
TABLE 1 simulation design parameters
| H＝5s | f 0 ＝50Hz |
| P L ＝700MW | P base ＝2000MW |
| P PV1 ＝1000MW | P PV2 ＝500MW |
| Δf max ＝0.3Hz | Z＝0.2Ω |
Table 2 line loss of photovoltaic power generation system
And a second case: the frequency modulation effect does not reach the predetermined value. Table 3 shows the simulation design parameters of the simulink, f, for MATLAB 0 Rated frequency for steady state operation of the system; h is the inertial time constant of the synchronous machine; p (P) L Maximum disturbance power which can occur to the power distribution network system; p (P) PVi Rated active power of the ith photovoltaic power generation system; p (P) base Rated power of the synchronous machine; Δf max Maximum steady-state frequency allowed for power distribution networkDeviation.
By simulation analysis, the frequency response effect is obtained as shown in FIG. 4, Δf at an initial value of 0 0 =0.36 Hz, at this time, the initial value K can be obtained from the formulas (1), (3) 1 ＝166MW/Hz，K 2 =83 MW/Hz. From the simulated frequency response waveform, it can be seen that the frequency support of the photovoltaic power generation system does not achieve the expected effect at this time, Δf 1 =0.333 Hz, line loss P L1 ＝3.1583MW，P L2 0.7896MW, bus loss P L = 3.9479MW, since the expected value is set to 0.3Hz, by comparison Δf 1 And Δf max Equal ratio of increase K i Value of K at this time 1 ＝300MW/Hz，K 2 =150 MW/Hz, again simulating that the frequency deviation corresponds to the expected value, at which time the line loss P L1 ＝3.3243MW，P L2 0.8311MW, bus loss P Total L = 4.1553MW; then obtaining new control parameter K through optimization constraint 1 ＝284MW/Hz，K 2 ＝166MW/Hz，P L1 ＝3.3042MW，P L2 0.8411MW, bus loss P Total L = 4.1454MW. The line losses are shown in table 4 below. The table shows that the optimized line loss is minimum, the obtained frequency change rate is within the allowable maximum frequency change of the power distribution network, and the simulation result is consistent with the theoretical control parameter setting flow. Simulation results show that the distributed photovoltaic power generation system can be simply, conveniently and effectively designed to coordinate with control parameters of frequency modulation.
TABLE 3 simulation design parameters
| H＝5s | f 0 ＝50Hz |
| P L ＝750MW | P base ＝2000MW |
| P PV1 ＝1000MW | P PV2 ＝500MW |
| Δf max ＝0.3Hz | Z＝0.2Ω |
Table 4 line loss of photovoltaic power generation system
Example 2
The embodiment provides a distributed photovoltaic power generation system frequency modulation control parameter setting device, it includes:
photovoltaic power generation system control unit: the distributed photovoltaic power generation system boosts voltage through a direct current converter, controls direct current voltage through a capacitor, and is connected with a grid through an alternating current-direct current converter, so that spare allowance of equipment is reserved to provide frequency modulation supporting capability during power generation; the AC/DC converter of the photovoltaic power generation system is controlled by adopting a constant DC voltage; the direct current converter of the photovoltaic power generation system adopts constant power control, and a feedback branch circuit of frequency deviation is introduced to the direct current converter;
power system frequency modulation support determination capability unit: determining the frequency modulation supporting capacity of a single photovoltaic power generation system in the distributed photovoltaic power generation system by using the spare allowance of the equipment;
active power control parameter initial value design unit: after the frequency modulation supporting capacity of a single photovoltaic power generation system to the power system is calculated, the initial value design of the active power control parameter of the single photovoltaic system in the distributed photovoltaic power generation system is carried out;
active power control parameter acquisition unit: and simulating the distributed photovoltaic power generation system with the initial value of the active power control parameter to obtain the active power control parameter with minimum line loss.
In the power system frequency modulation support determination capability unit, a photovoltaic power generation system adopts a frequency modulation strategy based on active power instruction adjustment: inputting an active power adjustment instruction to a single photovoltaic power generation system, and leading out a feedback branch controlled by stable frequency deviation delta f;
under grid disturbance, the distributed photovoltaic power generation system provides active power support for the power distribution network, and steady-state frequency deviation needs to meet the constraint of a grid frequency guide rule:
Δf≤Δf max
wherein Δf max Maximum steady-state frequency deviation allowed for the distribution network;
in the ith photovoltaic power generation system, the active power control parameter of the stable frequency deviation delta f control feedback branch is K i The method comprises the steps of carrying out a first treatment on the surface of the Taking into account the active power control parameter K i The value needs to meet the self standby allowance of the photovoltaic power generation system, the regulating capacity needs to meet the photovoltaic rated active power with steady-state output less than or equal to eta times according to the self situation and actual demand of equipment, and the constraint conditions are as follows:
Δf max ·K i ≤ηP PVi
wherein P is pvi Rated active power of the ith photovoltaic power generation system; η is the duty ratio of the spare margin of the photovoltaic power generation system.
In the active power control parameter initial value design unit, the active power control parameter K i The initial value of (1) is taken by the spare margin of the device itself to provide half of the maximum output.
The active power control parameter acquisition unit is divided into two types when performing simulation:
first, if the frequency modulation effect reaches a predetermined value, K is determined at that time i The value is the initial value;
second, if the frequency modulation effect does not reach the predetermined value, Δf is set according to the obtained Δf comparison max Obtaining the power delta P required by the system frequency modulation reaching the expected value, and proportionally increasing the active power control parameter K i Obtaining new reference value, re-simulating until the frequency modulation effect reaches the expected value, and obtaining K at the moment i The value is taken as an initial value。
For the frequency modulation capability of each photovoltaic power generation system of the optimal distributed photovoltaic power generation system, the active power control parameter under the condition of minimum line loss of the photovoltaic power generation grid-connected system is obtained, and the optimization constraint conditions are as follows:
ΔP total (S) Representing the total active power, ΔP, required to be provided by the distributed photovoltaic power generation system frequency support i And the active power output of the frequency support of the ith photovoltaic power generation system is represented.
While the foregoing description of the embodiments of the present invention has been presented in conjunction with the drawings, it should be understood that it is not intended to limit the scope of the invention, but rather, it is intended to cover all modifications or variations within the scope of the invention as defined by the claims of the present invention.
Claims (10)
1. The frequency modulation control parameter setting method of the distributed photovoltaic power generation system is characterized by comprising the following steps of:
step 1), boosting by a direct current converter, controlling direct current voltage by using a capacitor, and then connecting the power to a grid by an alternating current-direct current converter, wherein during power generation, spare allowance of equipment is reserved to provide frequency modulation supporting capacity; the AC/DC converter of the photovoltaic power generation system is controlled by adopting a constant DC voltage; the direct current converter of the photovoltaic power generation system adopts constant power control, and a feedback branch circuit of frequency deviation is introduced to the direct current converter;
step 2), determining the frequency modulation supporting capacity of a single photovoltaic power generation system in the distributed photovoltaic power generation system by using the spare allowance of the equipment; after the frequency modulation supporting capacity of a single photovoltaic power generation system to the power system is calculated, the initial value design of the active power control parameter of the single photovoltaic system in the distributed photovoltaic power generation system is carried out;
and 3) carrying out simulation on the distributed photovoltaic power generation system by taking the initial value of the active power control parameter to obtain the active power control parameter with the minimum line loss.
2. The tuning method of tuning control parameters of a distributed photovoltaic power generation system according to claim 1, wherein in step 2), the photovoltaic power generation system adopts a tuning strategy adjusted based on an active power command: inputting an active power adjustment instruction to a single photovoltaic power generation system, and leading out a feedback branch controlled by stable frequency deviation delta f;
under grid disturbance, the distributed photovoltaic power generation system provides active power support for the power distribution network, and steady-state frequency deviation needs to meet the constraint of a grid frequency guide rule:
Δf≤Δf max
wherein Δf max Maximum steady-state frequency deviation allowed for the distribution network;
in the ith photovoltaic power generation system, the active power control parameter of the stable frequency deviation delta f control feedback branch is K i The method comprises the steps of carrying out a first treatment on the surface of the Taking into account the active power control parameter K i The value needs to meet the self standby allowance of the photovoltaic power generation system, the regulating capacity needs to meet the photovoltaic rated active power with steady-state output less than or equal to eta times according to the self situation and actual demand of equipment, and the constraint conditions are as follows:
Δf max ·K i ≤ηP PVi
wherein P is pvi Rated active power of the ith photovoltaic power generation system; η is the duty ratio of the spare margin of the photovoltaic power generation system.
3. The tuning method of frequency modulation control parameters of a distributed photovoltaic power generation system according to claim 2, wherein in step 2), the active power control parameter K is i The initial value of (1) is taken by the spare margin of the device itself to provide half of the maximum output.
4. The tuning method of frequency modulation control parameters of a distributed photovoltaic power generation system according to claim 2, wherein step 3) performs simulation, and is divided into two types:
first, if the frequency modulation effect reaches a predetermined value, K is determined at that time i The value is the initial value;
second, if the frequency modulation effect does not reach the predetermined value, Δf is set according to the obtained Δf comparison max Obtaining the power delta P required by the system frequency modulation reaching the expected value, and proportionally increasing the active power control parameter K i Obtaining new reference value, re-simulating until the frequency modulation effect reaches the expected value, and obtaining K at the moment i The value is taken as an initial value.
5. The tuning method of tuning control parameters of a distributed photovoltaic power generation system according to claim 4, wherein for the tuning capability of each photovoltaic power generation system of the optimal distributed photovoltaic power generation system, the active power control parameters with minimum line loss of the photovoltaic power generation grid-connected system are obtained, and the optimization constraint conditions are as follows:
ΔP total (S) Representing the total active power, ΔP, required to be provided by the distributed photovoltaic power generation system frequency support i And the active power output of the frequency support of the ith photovoltaic power generation system is represented.
6. Frequency modulation control parameter setting device of distributed photovoltaic power generation system, its characterized in that includes:
photovoltaic power generation system control unit: the distributed photovoltaic power generation system boosts voltage through a direct current converter, controls direct current voltage through a capacitor, and is connected with a grid through an alternating current-direct current converter, so that spare allowance of equipment is reserved to provide frequency modulation supporting capability during power generation; the AC/DC converter of the photovoltaic power generation system is controlled by adopting a constant DC voltage; the direct current converter of the photovoltaic power generation system adopts constant power control, and a feedback branch circuit of frequency deviation is introduced to the direct current converter;
power system frequency modulation support determination capability unit: determining the frequency modulation supporting capacity of a single photovoltaic power generation system in the distributed photovoltaic power generation system by using the spare allowance of the equipment;
active power control parameter initial value design unit: after the frequency modulation supporting capacity of a single photovoltaic power generation system to the power system is calculated, the initial value design of the active power control parameter of the single photovoltaic system in the distributed photovoltaic power generation system is carried out;
active power control parameter acquisition unit: and simulating the distributed photovoltaic power generation system with the initial value of the active power control parameter to obtain the active power control parameter with minimum line loss.
7. The tuning device for the tuning control parameters of the distributed photovoltaic power generation system according to claim 6, wherein in the power system tuning support determining capability unit, the photovoltaic power generation system adopts a tuning strategy based on active power command adjustment: inputting an active power adjustment instruction to a single photovoltaic power generation system, and leading out a feedback branch controlled by stable frequency deviation delta f;
under grid disturbance, the distributed photovoltaic power generation system provides active power support for the power distribution network, and steady-state frequency deviation needs to meet the constraint of a grid frequency guide rule:
Δf≤Δf max
wherein Δf max Maximum steady-state frequency deviation allowed for the distribution network;
in the ith photovoltaic power generation system, the active power control parameter of the stable frequency deviation delta f control feedback branch is K i The method comprises the steps of carrying out a first treatment on the surface of the Taking into account the active power control parameter K i The value needs to meet the self standby allowance of the photovoltaic power generation system, the regulating capacity needs to meet the rated active power of which the steady-state output is smaller than or equal to eta times according to the self situation and the actual demand of the equipment, and the constraint conditions are as follows:
Δf max ·K i ≤ηP PVi
wherein P is pvi Rated active power of the ith photovoltaic power generation system; η is the duty ratio of the spare margin of the photovoltaic power generation system.
8. According to claim 6The frequency modulation control parameter setting device of the distributed photovoltaic power generation system is characterized in that the active power control parameter K is in the active power control parameter initial value design unit i The initial value of (1) is taken by the spare margin of the device itself to provide half of the maximum output.
9. The tuning device for frequency modulation control parameters of distributed photovoltaic power generation system according to claim 6, wherein the active power control parameter obtaining unit performs simulation time division into two types:
first, if the frequency modulation effect reaches a predetermined value, K is determined at that time i The value is the initial value;
second, if the frequency modulation effect does not reach the predetermined value, Δf is set according to the obtained Δf comparison max Obtaining the power delta P required by the system frequency modulation reaching the expected value, and proportionally increasing the active power control parameter K i Obtaining new reference value, re-simulating until the frequency modulation effect reaches the expected value, and obtaining K at the moment i The value is taken as an initial value.
10. The tuning device for tuning control parameters of a distributed photovoltaic power generation system according to claim 9, wherein for the tuning capability of each photovoltaic power generation system of the optimal distributed photovoltaic power generation system, the active power control parameter under the condition that the line loss of the photovoltaic power generation grid-connected system is minimum is obtained, and the optimization constraint condition is as follows:
ΔP total (S) Representing the total active power, ΔP, required to be provided by the distributed photovoltaic power generation system frequency support i And the active power output of the frequency support of the ith photovoltaic power generation system is represented.
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