CN104600725A - Photovoltaic series compensation system - Google Patents
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- CN104600725A CN104600725A CN201310533488.XA CN201310533488A CN104600725A CN 104600725 A CN104600725 A CN 104600725A CN 201310533488 A CN201310533488 A CN 201310533488A CN 104600725 A CN104600725 A CN 104600725A
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- 239000003990 capacitor Substances 0.000 claims abstract description 33
- 238000006243 chemical reaction Methods 0.000 claims abstract description 20
- 238000010248 power generation Methods 0.000 claims description 21
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Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/28—Arrangements for balancing of the load in a network by storage of energy
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- H02J3/385—
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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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- 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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- 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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E70/00—Other energy conversion or management systems reducing GHG emissions
- Y02E70/30—Systems combining energy storage with energy generation of non-fossil origin
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- Charge And Discharge Circuits For Batteries Or The Like (AREA)
- Supply And Distribution Of Alternating Current (AREA)
Abstract
The invention provides a photovoltaic series compensation system. The system comprises a DC bus, a capacitor, an inverter, a transformer, a filter, an AC energy storing system and an energy storing control device; one end of the primary side of the transformer is electrically connected with the output end of the inverter; the filter is equipped with an input end which forms a continuous current circuit with the primary side of the transformer and the output end of the inverter, and an output end which is connected in parallel to a power grid; the AC energy storing system comprises an energy storing device and an energy storing conversion device; the energy storing control device is used for detecting voltage and current in the DC bus; when the voltage of the DC bus is more than a preset upper limit value or less than a preset lower limit value, the energy storing control device controls the energy storing conversion device to charge or discharge the energy storing device according to the voltage and current in the DC bus so as to provide dynamic compensation voltage to the output voltage of the inverter, and therefore, a photovoltaic generating device can work at the maximum power point. With the adoption of the photovoltaic series compensation system, the maximum power point range can be expanded, and meanwhile, the grid voltage compensation and energy storage functions can be achieved.
Description
Technical Field
The invention relates to the field of photovoltaic power generation, in particular to a photovoltaic series compensation system.
Background
In a solar grid-connected power generation system, how to increase the output power of a solar battery, the solar energy is fully utilized, and the important significance is achieved in improving the power generation efficiency of the whole solar grid-connected power generation system.
Through research on the output power characteristics of the solar cell, the output power of the solar cell is found to be related to parameters such as illumination intensity, ambient temperature and the like, and in order to enable a photovoltaic grid-connected power generation system to work near a maximum output power point, a large number of Maximum Power Point Tracking (MPPT) are adopted at present, and the maximum power output of the solar cell is realized by changing the output voltage of the solar cell.
The MPPT control strategy in the Chinese patent application publication number CN102723740A can quickly track the severely changed illumination environment and improve the output power of the solar battery.
In the current photovoltaic grid-connected power generation system, if the Maximum Power Point (MPP) range of the photovoltaic grid-connected power generation system is 450v-1000v, on one hand, if the environmental change in a certain region or a certain time period is large, so that the maximum power point of the photovoltaic cell is 400 v (i.e. lower limit value of the maximum power point range), the inverter in the photovoltaic grid-connected power generation system cannot work, and thus the electric energy generated by the photovoltaic cell cannot be output to the power grid, and the solar energy is only wasted, which results in the reduction of the utilization efficiency of the solar energy. On the other hand, when the output voltage of the photovoltaic cell is 450V, if the output voltage is reversed under the maximum modulation degreeThe line voltage of the alternating current at the output of the converter has an effective value ofApproximately 180 volts, in order to stably provide 500kW of output power to the power grid, the effective value of the ac phase current reaches 910 amps, so that a semiconductor switch tube with a current over 910 amps must be selected, which greatly wastes the current selection capacity of the switch tube. Meanwhile, the limitation of the open-circuit voltage of the photovoltaic panel also makes the voltage of the semiconductor switching tube reach the highest voltage of the photovoltaic panel, and assuming that the maximum power point range is 450V-1000V, the voltage of the switching device should not be less than 1000V, but the actual device is selected to be the nominal 1700V. The voltage selection capacity of the switching tube is greatly wasted. Therefore, the problems of output efficiency, utilization rate and the like of the solar cell are not fundamentally solved at present.
Disclosure of Invention
In view of the above prior art, the present invention aims to provide a photovoltaic series compensation system, which includes:
the direct current bus comprises a positive terminal and a negative terminal, and the positive terminal and the negative terminal are electrically connected with the output end of the photovoltaic power generation device;
a capacitor electrically connected between the positive and negative terminals;
an inverter having an input electrically connected between the positive and negative terminals;
the transformer is provided with a primary side and a secondary side, and one end of the primary side of the transformer is electrically connected with the output end of the inverter;
a filter having an input end forming a freewheel loop with a primary side of the transformer and an output end of the inverter and an output end connected in parallel to a power grid;
the alternating-current energy storage system comprises an energy storage device and an energy storage conversion device, and the energy storage device is connected to the secondary side of the transformer through the energy storage conversion device;
the energy storage control device is used for detecting the voltage and the current on the direct current bus, when the voltage on the direct current bus is higher than a preset upper limit value, the energy storage control device controls the energy storage conversion device to charge the energy storage device according to the voltage and the current on the direct current bus, so that dynamic compensation voltage is provided for the output voltage of the inverter, the photovoltaic power generation device works at the maximum power point, and when the voltage on the direct current bus is lower than a preset lower limit value, the energy storage control device controls the energy storage conversion device to discharge the energy storage device according to the voltage and the current on the direct current bus, so that dynamic compensation voltage is provided for the output voltage of the inverter, and the photovoltaic power generation device works at the maximum power point.
The photovoltaic series compensation system improves the maximum power point range of the photovoltaic power generation device, and theoretically enables the maximum power point range of the photovoltaic power generation device to be from more than zero to the open-circuit voltage of the photovoltaic power generation device. The grid voltage compensation is provided, so that the problem of low voltage ride through capability is solved, and an energy storage function is provided. The utilization rate of solar energy is improved.
Preferably, the energy storage control device controls the inverter to operate in a modulation degree range with the highest efficiency. The utilization rate of semiconductor switching devices in the inverter can be improved.
Preferably, when the voltage on the dc bus is higher than a predetermined upper limit value, the energy storage control device controls the inverter to operate at a first modulation degree within the modulation degree range with the highest efficiency; and when the voltage on the direct current bus is lower than a preset lower limit value, the energy storage control device controls the inverter to work under a second modulation degree within the modulation degree range with the highest efficiency, and the first modulation degree and the second modulation degree are not equal. More preferably, the first modulation degree is a lower limit value in a modulation degree range in which efficiency is highest, and the second modulation degree is an upper limit value in a modulation degree range in which efficiency is highest. The inverter works at the upper limit value or the lower limit value within the modulation degree range with the highest efficiency, so that the dynamic compensation voltage value can be effectively reduced, and the loss of a semiconductor switching device in the inverter is reduced.
Preferably, the inverter is a full-bridge inverter, and includes three bridge arms connected in parallel between the positive terminal and the negative terminal, and the full-bridge inverter has a first node, a second node, and a third node; the transformer comprises three phases; (ii) a The alternating current energy storage system is a three-phase alternating current energy storage system. Three-phase alternating current is provided for a power grid through a three-phase transformer and a three-phase alternating current energy storage system, and the requirement of commercial power is met.
More preferably, the filter is a three-phase LCL filter. The LCL filter has low cost and good filtering effect.
Preferably, the inverter is a two-leg inverter, and the two-leg inverter has a fourth node and a fifth node; the transformer is a single-phase transformer, and one end of the primary side of the single-phase transformer is electrically connected with the fourth node; the alternating current energy storage system is a single-phase alternating current energy storage system. This embodiment is used to provide single phase alternating current to the grid.
More preferably, the filter is a single-phase LCL filter. The LCL filter has low cost and good filtering effect.
Preferably, the output of the filter is connected to the primary side of a transformer in the power grid.
Drawings
The drawings are only for purposes of illustrating and explaining the present invention and are not to be construed as limiting the scope of the present invention. Wherein,
fig. 1 is a circuit diagram of a photovoltaic series compensation system according to a first embodiment of the invention;
fig. 2 is a circuit diagram of a photovoltaic series compensation system according to a second embodiment of the present invention.
Symbolic description of main devices
1 positive terminal and 2 negative terminal
3 inverter 4 AC energy storage system
41 energy storage device 42 energy storage control device
5 three-phase transformer 23 inverter
24 exchange energy storage system 25 LCL filter
26 a.c. electromagnetic compatible filter 27 transformer
28 energy storage control device 29 energy storage device
43 energy storage conversion device 20 energy storage conversion device
C1-C5 capacitor
T1-T10 insulated gate bipolar transistor
Tr1-Tr4 transformer
L1, L2 inductance
Detailed Description
In order to more clearly understand the technical features, objects, and effects of the present invention, embodiments of the present invention will now be described with reference to the accompanying drawings.
Fig. 1 is a circuit diagram of a photovoltaic series compensation system according to a first embodiment of the present invention. As shown in fig. 1, the photovoltaic series compensation system includes a positive terminal 1 and a negative terminal 2 of a dc bus, a capacitor C1, an inverter 3, a transformer U-phase Tr1, a transformer V-phase Tr2, a transformer W-phase Tr3, a filter capacitor C2, a filter capacitor C3, a filter capacitor C4, an ac energy storage system 4, and an energy storage control device 42. The positive terminal 1 and the negative terminal 2 are used for connecting an output end of a photovoltaic power generation device (not shown in the figure), two terminals of the capacitor C1 are respectively connected to the positive terminal 1 and the negative terminal 2, and the photovoltaic power generation device converts the obtained solar energy into direct current and outputs the direct current to the capacitor C1. The inverter 3 may be a full-bridge inverter or other photovoltaic inverters, such as a multi-level inverter, wherein the full-bridge inverter includes three arms connected in parallel between the positive terminal 1 and the negative terminal 2, and each arm has two igbts connected in series. There is an insulated gate bipolar transistor T1 and an insulated gate bipolar transistor T2 in the first leg, with a node N1 between the insulated gate bipolar transistor T1 and the insulated gate bipolar transistor T2. There is an insulated gate bipolar transistor T3 and an insulated gate bipolar transistor T4 in the second leg, with a node N2 between the insulated gate bipolar transistor T3 and the insulated gate bipolar transistor T4. In the third leg there is an insulated gate bipolar transistor T5 and an insulated gate bipolar transistor T6, with a node N3 between the insulated gate bipolar transistor T5 and the insulated gate bipolar transistor T6. In the present embodiment, the inverter 3 can convert the dc power on the capacitor C1 into ac power for output by a control method in the prior art, and make the conductive angles of the phases of the three-phase power differ by 120 °, the positive terminal 1 and the negative terminal 2 are input terminals of the inverter 3, and the node N1, the node N2 and the node N3 are output terminals of the inverter 3. In other embodiments, a full-bridge inverter may be formed by mosfet instead of the igbt in this embodiment. The primary side of the transformer U-phase Tr1 has a terminal U1 and a terminal U2, and the terminal U1 is connected to a node N1. The primary side of the transformer V phase Tr2 has a terminal V1 and a terminal V2, and the terminal V1 is electrically connected to the node N2. The primary side of the transformer W phase Tr3 has a terminal W1 and a terminal W2, and the terminal W1 is connected to a node N3. In the present embodiment, the ac energy storage system 4 mainly includes an energy storage device 41 and an energy storage conversion device 43, one end of the energy storage conversion device 43 is connected to the secondary sides of three phases Tr1-Tr3 of the transformer, and the other end of the energy storage conversion device 43 is connected to the energy storage device 41, and in the embodiment of the present invention, the energy storage conversion device 43 may include an ac/dc converter and a dc/dc converter, and is used for controlling the energy storage device 41 to charge or discharge. The energy storage control device 42 is configured to detect a voltage across the capacitor C1 and a current in the dc bus, and control a modulation degree of the inverter 3 according to the voltage across the capacitor C1, so that the inverter 3 operates in a modulation degree range with the highest efficiency, and meanwhile, the energy storage control device 42 can provide a dynamic compensation voltage to an output terminal of the inverter 3 according to the voltage across the capacitor C1 and the current in the dc bus, so that the photovoltaic power generation apparatus operates at the highest power point. The capacitor C2, the capacitor C3 and the capacitor C4 are connected in a triangle, that is, the capacitor C2, the capacitor C3 and the capacitor C4 are connected in a ring shape. A node of the capacitor C2 and the capacitor C4 is connected to a terminal U2 on the primary side of the transformer U phase Tr1, a node of the capacitor C2 and the capacitor C3 is connected to a terminal V2 on the primary side of the transformer V phase Tr2, a node of the capacitors C3 and C4 is connected to a terminal W2 on the primary side of the transformer W phase Tr3, and at the same time, a terminal U2 on the primary side of the transformer U phase Tr1, a terminal V2 on the primary side of the transformer V phase Tr2, and a terminal W2 on the primary side of the transformer W phase Tr3 are connected to an input terminal of the three-phase transformer 5, and an output terminal of the three-phase transformer 5 is. Since the actual transformers all have more or less leakage inductances, in this embodiment, the leakage inductances in the transformer Tr1, the transformer Tr2, the transformer Tr3, and the three-phase transformer 5 and the capacitors C2, C3, and C4 connected in a delta configuration constitute a three-phase LCL filter, which reduces components and cost.
The photovoltaic power generation device (such as a photovoltaic cell assembly) converts light energy into electric energy, the electric energy is stored on a capacitor C1 through a positive terminal 1 and a negative terminal 2 of a direct current bus, an energy storage control device 42 detects voltage on the direct current bus and current in the direct current bus, when the voltage between the positive terminal 1 and the negative terminal 2 of the direct current bus is between a preset lower limit value and an upper limit value, an alternating current energy storage system 4 does not provide voltage compensation at the moment, namely, the energy storage device 41 does not perform any charging and discharging processes, the energy storage control device 42 controls an inverter 3 according to a traditional photovoltaic inverter control mode, and the inverter 3 works in a modulation degree range with the highest efficiency, so that the photovoltaic cell assembly works at the maximum power point, and the electric energy generated by the photovoltaic cell assembly can be directly output to a power grid at the moment. Wherein the predetermined upper and lower limit values in the photovoltaic series compensation system are determined according to the grid voltage and the range of modulation index of the inverter 3 at the highest efficiency.
When the voltage between the positive terminal 1 and the negative terminal 2 of the dc bus bar is greater than a predetermined upper limit value, at this time, the output power of the photovoltaic cell assembly is correspondingly increased, the energy storage control device 42 controls the inverter 3 to work under a certain fixed modulation degree with the highest efficiency, for example, the inverter 3 is operated at a lower limit value within a modulation degree range in which the efficiency is the highest, and the injection current vector and the dynamic compensation voltage vector injected into the grid are controlled by a vector control method, meanwhile, the directions of the injected current vector and the dynamic compensation voltage vector are opposite, at this time, the energy storage control device 42 controls the energy storage conversion device 43 to charge and store energy in the energy storage device 41, and the energy storage control device 42 controls the charging state of the energy storage device 41 according to the voltage and the current on the direct current bus to provide a dynamic compensation voltage for the output end of the inverter 3, so that the photovoltaic cell assembly works at the maximum power point.
When the voltage between the positive terminal 1 and the negative terminal 2 of the direct current bus bar is smaller than the predetermined lower limit value, the output power of the photovoltaic cell assembly is reduced correspondingly. The energy storage control device 42 controls the inverter 3 to operate under a certain fixed modulation degree with the highest efficiency, for example, the inverter 3 operates at an upper limit value within a modulation degree range with the highest efficiency, and controls the ac energy storage system 4 to provide a dynamic compensation voltage vector through a vector control method, the dynamic compensation voltage vector is in the same direction as a current vector injected into a power grid, at this time, the energy storage control device 42 controls the energy storage conversion device 43 to enable the energy storage device 41 to start discharging, and the energy storage control device 42 controls the discharging state of the energy storage device 41 to provide a dynamic compensation voltage for the output end of the inverter 3 according to the voltage on the dc bus and the current, so that the photovoltaic cell assembly operates at the maximum power point.
Compared with the prior art in the background art, when the output voltage of the photovoltaic cell assembly is very low or is far lower than the direct-current voltage required by grid connection of the inverter, the inverter can still normally work at the moment, and the photovoltaic cell assembly works at the maximum power point, so that the part of solar energy is utilized and output to a power grid. Thus, the photovoltaic series compensation system of the present invention theoretically allows the maximum power point of the photovoltaic power plant (or photovoltaic cell assembly) to range from 0 volts to the open circuit voltage of the photovoltaic power plant. Meanwhile, the maximum working voltage and the maximum working current of the insulated gate bipolar transistor of the inverter can be reduced, the utilization rate of devices is improved, and the insulated gate bipolar transistor or other semiconductor switch tubes capable of bearing larger current do not need to be selected, so that the equipment cost is reduced. In addition, the photovoltaic series compensation system has the functions of network voltage compensation and energy storage, and simultaneously solves the problems of low voltage ride through and grid-connected energy storage.
Fig. 2 is a circuit diagram of a photovoltaic series compensation system according to a second embodiment of the present invention. As shown in fig. 2, the photovoltaic series compensation system includes a positive terminal 1 and a negative terminal 2 of the dc bus, a capacitor C1, an inverter 23, a transformer Tr4, an energy storage control device 28, an ac energy storage system 24, and an LCL filter 25. The inverter 23 is a two-leg inverter, and includes two legs connected in parallel between the positive terminal 1 and the negative terminal 2, and each leg has two igbts connected in series. There is an insulated gate bipolar transistor T7 and an insulated gate bipolar transistor T8 in the first leg, with a node N4 between the insulated gate bipolar transistor T7 and the insulated gate bipolar transistor T8. There is an insulated gate bipolar transistor T9 and an insulated gate bipolar transistor T10 in the second leg, with a node N5 between the insulated gate bipolar transistor T9 and the insulated gate bipolar transistor T10. The primary side of the transformer Tr4 has a terminal 21 and a terminal 22, the terminal 21 is connected to a node N4, the secondary side of the transformer Tr4 is connected to an ac energy storage system 24, the ac energy storage system 24 includes an energy storage device 29 and an energy storage conversion device 20, and the energy storage device 29 is connected to the secondary side of the transformer Tr4 through the energy storage conversion device 20. One end of one of the filter inductors L1 of the LCL filter is connected to the terminal 22, one end of the filter capacitor C5 is connected to the node N5, and one end of the filter inductor L1 and one end of the filter capacitor C5 serve as input terminals and constitute a freewheeling circuit of the transformer Tr 4. One end of the filter inductor L2 is used as the output of the LCL filter and is connected to the grid-side transformer 27 through the ac emc filter 26 to provide power output to the grid. In the first embodiment, an ac electromagnetic compatibility filter may also be connected between the filter and the input of the three-phase transformer 5. The photovoltaic series compensation system of this embodiment can also make the inverter 23 work when the output voltage of the photovoltaic cell module is lower than the predetermined lower limit value, so as to output the solar energy generated by the photovoltaic cell module to the power grid, and the working principle is the same as that in fig. 1, and is not described herein again.
In the above embodiment of the present invention, the positive electrode terminal 1 and the negative electrode terminal 2 may be connected to a dc electromagnetic compatibility filter, respectively. In other embodiments of the present invention, the inverter is not limited to the full-bridge inverter 3 shown in fig. 1 and the two-leg inverter 23 shown in fig. 2, and may be another inverter that converts direct current into alternating current. The filter 25 in the present invention may be an LCL filter, wherein two filter inductances in the LCL filter may be leakage inductances in a transformer, that is, the LCL filter is composed by the leakage inductances in the transformer as shown in fig. 1, thereby reducing components and cost. In the filter shown in fig. 1, the capacitor C2, the capacitor C3 and the capacitor C4 may also be star-connected. In other embodiments, the filter may also be an LC filter.
It should be understood that although the present description has been described in terms of various embodiments, not every embodiment includes only a single embodiment, and such description is for clarity purposes only, and those skilled in the art will recognize that the embodiments described herein may be combined as suitable to form other embodiments, as will be appreciated by those skilled in the art.
The above description is only an exemplary embodiment of the present invention, and is not intended to limit the scope of the present invention. Any equivalent alterations, modifications and combinations can be made by those skilled in the art without departing from the spirit and principles of the invention.
Claims (8)
1. A photovoltaic series compensation system, comprising:
the direct current bus comprises a positive terminal and a negative terminal, and the positive terminal and the negative terminal are electrically connected with the output end of the photovoltaic power generation device;
a capacitor electrically connected between the positive and negative terminals;
an inverter having an input electrically connected between the positive and negative terminals;
the transformer is provided with a primary side and a secondary side, and one end of the primary side of the transformer is electrically connected with the output end of the inverter;
a filter having an input end forming a freewheel loop with a primary side of the transformer and an output end of the inverter and an output end connected in parallel to a power grid;
the alternating-current energy storage system comprises an energy storage device and an energy storage conversion device, and the energy storage device is connected to the secondary side of the transformer through the energy storage conversion device;
the energy storage control device is used for detecting the voltage and the current on the direct current bus, when the voltage on the direct current bus is higher than a preset upper limit value, the energy storage control device controls the energy storage conversion device to charge the energy storage device according to the voltage and the current on the direct current bus, so that dynamic compensation voltage is provided for the output voltage of the inverter, the photovoltaic power generation device works at the maximum power point, and when the voltage on the direct current bus is lower than a preset lower limit value, the energy storage control device controls the energy storage conversion device to discharge the energy storage device according to the voltage and the current on the direct current bus, so that dynamic compensation voltage is provided for the output voltage of the inverter, and the photovoltaic power generation device works at the maximum power point.
2. The pv series compensation system of claim 1, wherein the energy storage control device controls the inverter to operate in a modulation range with a highest efficiency.
3. The photovoltaic series compensation system of claim 2,
when the voltage on the direct current bus is higher than a preset upper limit value, the energy storage control device controls the inverter to work under a first modulation degree within the modulation degree range with the highest efficiency; and
when the voltage on the direct current bus is lower than a preset lower limit value, the energy storage control device controls the inverter to work under a second modulation degree within the modulation degree range with the highest efficiency, and the first modulation degree and the second modulation degree are not equal.
4. The pv series compensation system of claim 3, wherein the first modulation factor is a lower limit value within the range of the highest efficiency modulation factor, and the second modulation factor is an upper limit value within the range of the highest efficiency modulation factor.
5. Photovoltaic series compensation system according to any one of claims 1 to 4,
the inverter is a full-bridge inverter and comprises three bridge arms connected in parallel between the positive terminal and the negative terminal, and the full-bridge inverter is provided with a first node, a second node and a third node; and
the alternating current energy storage system is a three-phase alternating current energy storage system.
6. The photovoltaic series compensation system of claim 5, wherein the filter is a three-phase LCL filter.
7. Photovoltaic series compensation system according to any one of claims 1 to 4,
the inverter is a two-bridge arm inverter, and the two-bridge arm inverter is provided with a fourth node and a fifth node;
the transformer is a single-phase transformer, and one end of the primary side of the single-phase transformer is electrically connected with the fourth node;
the alternating current energy storage system is a single-phase alternating current energy storage system.
8. The photovoltaic series compensation system of claim 7, wherein the filter is a single phase LCL filter.
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