CN115344828A - Photovoltaic power station power loss amount calculation method and system - Google Patents

Photovoltaic power station power loss amount calculation method and system Download PDF

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CN115344828A
CN115344828A CN202210847418.0A CN202210847418A CN115344828A CN 115344828 A CN115344828 A CN 115344828A CN 202210847418 A CN202210847418 A CN 202210847418A CN 115344828 A CN115344828 A CN 115344828A
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photovoltaic power
power station
unit
proportion
grid
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陈威
查道军
吴通华
戴魏
李新东
刘小宝
潘书燕
侯小凡
吴丹
杨增力
张侃君
陈永昕
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State Grid Hubei Electric Power Co Ltd
Electric Power Research Institute of State Grid Hubei Electric Power Co Ltd
NARI Group Corp
Nari Technology Co Ltd
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State Grid Hubei Electric Power Co Ltd
Electric Power Research Institute of State Grid Hubei Electric Power Co Ltd
NARI Group Corp
Nari Technology Co Ltd
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    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
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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
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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
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Abstract

The invention discloses a method and a system for calculating power loss of a photovoltaic power station.

Description

Photovoltaic power station power loss amount calculation method and system
Technical Field
The invention relates to a method and a system for calculating power loss of a photovoltaic power station, and belongs to the field of judgment of power loss of the photovoltaic power station.
Background
In recent years, the photovoltaic power generation technology is rapidly developed, the grid-connected scale of photovoltaic power generation is larger and larger, a large number of power electronic devices are connected into a power grid, the form of the power grid is changed, large-scale grid disconnection accidents easily occur when faults occur due to the fragility of the power electronic devices, and the power loss brings serious challenges to the safety and stability of the power grid. The study on the real-time calculation of the power loss of the photovoltaic power station by scholars at home and abroad is less, and no corresponding method exists at present.
Disclosure of Invention
The invention provides a method and a system for calculating power loss of a photovoltaic power station, which solve the problems disclosed in the background technology.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows:
a method for calculating power loss of a photovoltaic power station comprises the following steps:
in response to the occurrence of faults, the photovoltaic power station unit is divided into a normal operation unit, a low-voltage ride-through unit and a grid-off unit, and the proportion of the normal operation unit, the proportion of the low-voltage ride-through unit and the proportion of the grid-off unit in the photovoltaic power station are calculated according to the active current of a grid-connected point of the photovoltaic power station immediately before the occurrence of the faults, the active current of the grid-connected point of the photovoltaic power station in a steady state after the occurrence of the faults and the reactive current of the grid-connected point of the photovoltaic power station in the steady state after the occurrence of the faults;
and calculating the power loss amount of the photovoltaic power station during the fault period and the power loss amount of the photovoltaic power station after the fault is removed according to the proportion of the normal operation units, the proportion of the low-voltage ride-through units and the proportion of the off-line units in the photovoltaic power station.
Calculating the proportion of a normally-operated unit, the proportion of a low-voltage ride-through unit and the proportion of a grid-off unit in the photovoltaic power station, wherein the formula is as follows:
Figure BDA0003753433990000021
Figure BDA0003753433990000022
λ＝1-θ-η
wherein theta is the proportion of a normally operating unit in the photovoltaic power station, eta is the proportion of a low-voltage ride-through unit, lambda is the proportion of a grid-off unit, and i d_mea Is the active current of a grid-connected point of a photovoltaic power station in a steady state after a fault occurs i q_mea Reactive power of grid-connected points of photovoltaic power station in steady state after fault occurrenceCurrent, m is the total number of photovoltaic power station units, i d0 Active current of photovoltaic power station grid connection point immediately before fault occurrence, parameter i limit ＝1.2I N ，I N For rated current of inverter, U N Rated voltage of grid-connected point, U d Is the voltage of the grid-connected point in the dq coordinate,
Figure BDA0003753433990000023
set power factor angle and inverter reactive given value for normal operation
Figure BDA0003753433990000024
According to the proportion of a normally-operated unit, the proportion of a low-voltage ride-through unit and the proportion of an off-grid unit in a photovoltaic power station, calculating the power loss amount of the photovoltaic power station during a fault period and the power loss amount of the photovoltaic power station after the fault is removed, and the method comprises the following steps:
calculating the capacity of the normally operating unit, the capacity of the low voltage ride through unit and the capacity of the off-grid unit during the fault period according to the proportion of the normally operating unit, the proportion of the low voltage ride through unit and the proportion of the off-grid unit in the photovoltaic power station;
and calculating the power loss of the photovoltaic power station during the fault period and the power loss of the photovoltaic power station after the fault is removed according to the capacity of the normal operation unit, the capacity of the low-voltage ride-through unit and the capacity of the off-grid unit during the fault period.
The capacity of the normally operating units during the fault period is the product of the total number of the photovoltaic power station units, the single machine capacity of the photovoltaic power station units and the proportion of the normally operating units in the photovoltaic power station;
the capacity of the low-voltage ride-through unit in the fault period is the product of the total number of the photovoltaic power station units, the single-machine capacity of the photovoltaic power station units and the proportion of the low-voltage ride-through unit in the photovoltaic power station;
and the capacity of the off-line unit during the fault period is the product of the total number of the photovoltaic power station units, the single-machine capacity of the photovoltaic power station units and the proportion of the off-line units in the photovoltaic power station.
According to the capacity of a normal operation unit, the capacity of a low-voltage ride-through unit and the capacity of an off-line unit during the fault period, calculating the power loss amount of the photovoltaic power station during the fault period and the power loss amount of the photovoltaic power station after the fault is removed, and the method comprises the following steps:
according to a reactive priority principle of low voltage ride through of the photovoltaic power station, the power loss of the photovoltaic power station during the fault period is the sum of the capacity of a normal operation unit during the fault period and the capacity of a low voltage ride through unit during the fault period;
after the fault is removed, the low-voltage ride-through unit of the photovoltaic power station recovers to a normal operation state, and the power loss of the photovoltaic power station is the capacity of the off-grid unit during the fault period.
A photovoltaic power plant power loss amount calculation system, comprising:
the proportion calculation module is used for responding to the occurrence of faults, dividing the photovoltaic power station unit into a normal operation unit, a low-voltage ride-through unit and an off-line unit, and calculating the proportion of the normal operation unit, the proportion of the low-voltage ride-through unit and the proportion of the off-line unit in the photovoltaic power station according to the active current of the photovoltaic power station grid-connected point immediately before the occurrence of the faults, the active current of the photovoltaic power station grid-connected point in a steady state after the occurrence of the faults and the reactive current of the photovoltaic power station grid-connected point in the steady state after the occurrence of the faults;
and the loss amount calculation module is used for calculating the power loss amount of the photovoltaic power station during the fault period and the power loss amount of the photovoltaic power station after the fault is removed according to the proportion of the normal operation unit, the proportion of the low-voltage ride-through unit and the proportion of the off-grid unit in the photovoltaic power station.
The formula for the proportion calculation module to calculate the proportion of the normal operation unit, the proportion of the low voltage ride through unit and the proportion of the off-grid unit in the photovoltaic power station is as follows:
Figure BDA0003753433990000041
Figure BDA0003753433990000042
λ＝1-θ-η
wherein theta is the proportion of a normally operating unit in the photovoltaic power station, eta is the proportion of a low-voltage ride-through unit, lambda is the proportion of a grid-off unit, and i d_mea Active current i of grid-connected point of photovoltaic power station in steady state after fault occurrence q_mea M is the reactive current of the grid-connected point of the photovoltaic power station in a steady state after the fault occurs, i is the total number of the photovoltaic power station units d0 Active current of photovoltaic power station grid connection point immediately before fault occurrence, parameter i limit ＝1.2I N ，I N For rated current of inverter, U N Rated voltage of grid-connected point, U d Is the grid-connected point voltage in the dq coordinate,
Figure BDA0003753433990000043
set power factor angle and inverter reactive given value for normal operation
Figure BDA0003753433990000044
The loss calculation module is used for calculating the capacity of the normally-operated unit, the capacity of the low-voltage ride-through unit and the capacity of the off-line unit during the fault period according to the proportion of the normally-operated unit, the proportion of the low-voltage ride-through unit and the proportion of the off-line unit in the photovoltaic power station, and calculating the power loss of the photovoltaic power station during the fault period and the power loss of the photovoltaic power station after the fault is cut off according to the capacity of the normally-operated unit, the capacity of the low-voltage ride-through unit and the capacity of the off-line unit during the fault period.
A computer readable storage medium storing one or more programs, the one or more programs comprising instructions, which when executed by a computing device, cause the computing device to perform a photovoltaic power plant power loss amount calculation method.
A computing device comprising one or more processors, one or more memories, and one or more programs stored in the one or more memories and configured to be executed by the one or more processors, the one or more programs including instructions for performing a photovoltaic power plant power loss amount calculation method.
The invention achieves the following beneficial effects: according to the invention, the photovoltaic power station unit after the fault is divided into a normal operation unit, a low voltage ride through unit and a grid disconnection unit, the proportion of various units is calculated according to the active current and the reactive current of a grid connection point, the power loss of the photovoltaic power station can be effectively calculated according to the proportion, a quantitative reference is provided for an accurate generator tripping load control strategy, and the safety and the stability of a power grid under the condition of high-proportion new energy access are improved.
Drawings
FIG. 1 is a flow chart of the method of the present invention;
FIG. 2 is a detailed flow chart of the method of the present invention;
FIG. 3 is a diagram of a simulation system architecture;
FIG. 4 is a waveform diagram of an active current simulation result of a photovoltaic power station;
FIG. 5 is a waveform diagram of a reactive current simulation result of a photovoltaic power station.
Detailed Description
The invention is further described below with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.
As shown in fig. 1, a method for calculating a power loss amount of a photovoltaic power station includes the following steps:
step 1, in response to a fault, dividing a photovoltaic power station unit into a normal operation unit, a low-voltage ride-through unit and an off-line unit, and calculating the proportion of the normal operation unit, the proportion of the low-voltage ride-through unit and the proportion of the off-line unit in the photovoltaic power station according to the active current of a photovoltaic power station grid-connection point immediately before the fault occurs, the active current of the photovoltaic power station grid-connection point in a steady state after the fault occurs and the reactive current of the photovoltaic power station grid-connection point in the steady state after the fault occurs;
and 2, calculating the power loss of the photovoltaic power station during the fault period and the power loss of the photovoltaic power station after the fault is removed according to the proportion of the normal operation unit, the proportion of the low-voltage ride-through unit and the proportion of the off-grid unit in the photovoltaic power station.
According to the method, the photovoltaic power station unit after the fault is divided into a normal operation unit, a low-voltage ride-through unit and a grid disconnection unit, the proportion of various units is calculated according to the active current and the reactive current of a grid connection point, the power loss amount of the photovoltaic power station can be effectively calculated according to the proportion, a quantitative reference is provided for an accurate generator tripping load control strategy, and the safety and the stability of a power grid under the condition of high-proportion new energy access are improved.
As shown in fig. 2, when the method for calculating the power loss amount of the photovoltaic power station is implemented, a grid-connected point of the photovoltaic power station can be monitored in real time, specifically, active current and reactive current can be monitored, and when a fault occurs, such as a sudden change in current, the photovoltaic power station can be divided into a normal operation unit, a low voltage ride-through unit and an off-grid unit according to the requirements of grid-connected low voltage ride-through specifications of the photovoltaic power station.
In order to meet the grid-connected low-voltage ride through standard requirement of the photovoltaic power station, the specific control method comprises the following steps: when the photovoltaic grid-connected inverter normally operates, the photovoltaic grid-connected inverter is generally connected with the grid by a unit power factor, and when a fault occurs, the inverter needs to generate reactive power, and the control strategy of the inverter is divided into an active control part and a reactive control part.
The external regulation characteristic of the active part mainly depends on the voltage outer ring, and a control equation of the active current can be obtained:
Figure BDA0003753433990000071
wherein i d For the current reference value of the active control part,
Figure BDA0003753433990000072
for the bus voltage limit of the DC link, u dc Is the bus voltage, k, of the DC link p1 、k i1 The capacity proportion and the integral gain of an outer ring PI controller of an active control part are respectively.
The technical specification that the photovoltaic power station is connected into the power system shows that the output reactive current of the photovoltaic power station meets the following requirement:
Figure BDA0003753433990000073
wherein, I q For the output of reactive current of the photovoltaic power station, I N For rated current of inverter, U N Rated voltage of grid-connected point, U d The grid connection point voltage under the dq coordinate is obtained;
the equation satisfied by the reactive current may be as follows:
Figure BDA0003753433990000074
wherein k is p2 、k i2 Respectively is the capacity proportion and integral gain of an outer ring PI controller of a reactive power control part,
Figure BDA0003753433990000075
for given inverter reactive value, i q Is the reactive component in the grid side current, and L is the inverter inductance.
Due to the capacity limitation of the inverter, the active current should satisfy the following inequality constraint:
Figure BDA0003753433990000081
wherein, the parameter i limit ＝1.2I N
Then in the low voltage ride through process, the control model of photovoltaic power plant is as follows:
Figure BDA0003753433990000082
wherein C is a DC link voltage-stabilizing capacitor, P W Maximum power, U, output by the photovoltaic unit d 、I d The grid-connected point voltage and current, U, respectively in dq coordinates r To the inverter equivalent voltage loss, ω is the angular frequency.
After a fault occurs, due to the influence of practical factors such as different transmission line impedances and the like, under the control of the model, the photovoltaic power station unit can be divided into a normal operation unit, a low-voltage ride-through unit and a grid disconnection unit, wherein the proportion of the normal operation unit is defined as theta, the proportion of the low-voltage ride-through unit is defined as eta, the proportion of the grid disconnection unit is defined as lambda, and the proportion of the grid disconnection unit is theta + eta + lambda =1.
The capacity of a single machine is aMW assuming that the photovoltaic power station has m machine sets, so the capacity of the 3 types of machine sets can be determined by determining the proportion.
According to kirchhoff's current law, the active current I at the monitoring point of the outlet of the photovoltaic electric field dΣ And a reactive current I dΣ It can be expressed as:
Figure BDA0003753433990000091
considering that all the units have similar active and reactive output characteristics under the same control strategy, the control method comprises the following steps
Figure BDA0003753433990000092
Figure BDA0003753433990000093
Wherein i d_mea Is the active current of a grid-connected point of a photovoltaic power station in a steady state after a fault occurs i q_mea For reactive current i of grid-connected points of photovoltaic power stations in steady state after fault occurrence d_lvrt Active current i output for low voltage ride through units q_normal Reactive current, i, output for normal operation of the unit dΣ_cal Is the sum of active currents, i, output when all units are supposed to operate normally qΣ_cal The total reactive current is output when all the voltages of the set are supposed to pass through;
known, normally operating unit power factor
Figure BDA0003753433990000094
Then the
Figure BDA0003753433990000101
According to the formula, the proportion of each unit is as follows:
Figure BDA0003753433990000102
Figure BDA0003753433990000103
λ＝1-θ-η
wherein i d0 The active current of the grid-connected point of the photovoltaic power station immediately before the fault occurs,
Figure BDA0003753433990000104
the angle of the power factor of the normally running unit and the power factor of the normally running unit
Figure BDA0003753433990000105
Inverter reactive given value
Figure BDA0003753433990000106
The proportion of the normally operating units, the proportion of the low-voltage ride-through units and the proportion of the off-grid units in the photovoltaic power station can be calculated according to the active current of the grid-connected point of the photovoltaic power station immediately before the fault occurs, the active current of the grid-connected point of the photovoltaic power station in a steady state after the fault occurs and the reactive current of the grid-connected point of the photovoltaic power station in the steady state after the fault occurs.
Under the condition of calculating the proportion, calculating the capacity of the normally-operated unit, the capacity of the low-voltage ride-through unit and the capacity of the off-grid unit during the fault period according to the proportion of the normally-operated unit, the proportion of the low-voltage ride-through unit and the proportion of the off-grid unit in the photovoltaic power station; the capacity of the off-grid unit during the fault period is the product of the total number of the photovoltaic power station units, the single unit capacity of the photovoltaic power station units and the proportion of the off-grid unit in the photovoltaic power station, and can be respectively expressed by formulas: ma θ, ma η, ma λ.
Further, the photovoltaic power station power loss amount during the fault period and the photovoltaic power station power loss amount after the fault is removed can be calculated according to the capacity of the normal operation unit, the capacity of the low-voltage ride-through unit and the capacity of the off-grid unit during the fault period, and the method specifically comprises the following steps: according to the reactive priority principle of low voltage ride through of the photovoltaic power station, the power loss of the photovoltaic power station during the fault period is the sum delta P of the capacity of a normal running unit during the fault period and the capacity of a low voltage ride through unit during the fault period 1 = ma η + ma λ; after the fault is removed, the low-voltage ride-through unit of the photovoltaic power station recovers to a normal operation state, and the power loss of the photovoltaic power station is the capacity delta P of the off-line unit during the fault 2 ＝maλ。
In order to verify the method, a 9MW trunk line type photovoltaic power station simulation system is built in PSCAD/EMTDC and is shown in figure 3, three groups of 3 MW-capacity PV are connected to a photovoltaic power station bus through a box transformer and a collector wire and then are transmitted to a large power grid through a step-up transformer and a 220kV overhead line. And (3) setting a single-phase grounding short-circuit fault at the midpoint of the 220kV overhead line, monitoring the current of a grid-connected point, and performing simulation analysis on the fault steady state.
When the system runs to 0.3s, the A phase of the 220kV overhead line has a short circuit ground fault, the voltage of a grid connection point falls to 0pu, and the three groups of photovoltaic units are respectively in normal running, low voltage ride through and off-grid states, namely
Figure BDA0003753433990000121
Normal operating unit power factor
Figure BDA0003753433990000122
As shown in fig. 4 and 5, the output current of the photovoltaic unit is that the active current of the PV1 in normal operation fluctuates, but can still be kept at the rated value, and the reactive current is kept at 0; the active current of the PV2 with low voltage ride through is obviously reduced, and the reactive current is suddenly increased; the output current of the off-grid PV3 is not 0. A system of equations for θ, η, λ can be obtained:
Figure BDA0003753433990000123
solving theta =0.333, eta =0.346 and lambda =0.321, ignoring errors caused by a simulation environment, enabling the actual value of the unit offline capacity proportion to be basically consistent with the calculated value, and enabling the power loss of the photovoltaic power station to be 6.003MW during the fault period; after the fault is removed, the low-voltage ride-through unit of the photovoltaic power station recovers to a normal operation state, and the power loss caused by the off-line of the photovoltaic unit is 2.889MW.
The method can accurately judge the power loss amount of the photovoltaic power station during the voltage drop period, provides technical support for making power grid stable control measures such as the load cutting and the like of a power grid, is beneficial to realizing the stable control measures such as the accurate load cutting and the like of the power grid, only needs to monitor the current of a grid-connected point of the photovoltaic power station in the judging process, and is small in calculated amount, high in real-time performance and low in realization cost.
Based on the same technical scheme, the invention also discloses a software system of the method, and a photovoltaic power station power loss calculation system comprises:
and the proportion calculation module is used for responding to the fault occurrence, dividing the photovoltaic power station unit into a normal operation unit, a low voltage ride through unit and an off-line unit according to the grid-connected low voltage ride through standard requirement of the photovoltaic power station, and calculating the proportion of the normal operation unit, the proportion of the low voltage ride through unit and the proportion of the off-line unit in the photovoltaic power station according to the active current of the grid-connected point of the photovoltaic power station immediately before the fault occurrence, the active current of the grid-connected point of the photovoltaic power station in a steady state after the fault occurrence and the reactive current of the grid-connected point of the photovoltaic power station in the steady state after the fault occurrence.
The formula for the proportion calculation module to calculate the proportion of the normal operation unit, the proportion of the low-voltage ride through unit and the proportion of the off-grid unit in the photovoltaic power station is as follows:
Figure BDA0003753433990000131
Figure BDA0003753433990000132
λ＝1-θ-η
wherein theta is the proportion of a normally operating unit in the photovoltaic power station, eta is the proportion of a low-voltage ride-through unit, lambda is the proportion of a grid-off unit, and i d_mea Active current i of grid-connected point of photovoltaic power station in steady state after fault occurrence q_mea M is the reactive current of the grid-connected point of the photovoltaic power station in a steady state after the fault occurs, i is the total number of the photovoltaic power station units d0 Active current of photovoltaic power station grid connection point immediately before fault occurrence, parameter i limit ＝1.2I N ，I N For rated current of inverter, U N Rated voltage for grid-connected point, U d Is the grid-connected point voltage in the dq coordinate,
Figure BDA0003753433990000133
the angle of the power factor of the normally running unit and the power factor of the normally running unit
Figure BDA0003753433990000134
Inverter reactive given value
Figure BDA0003753433990000141
And the loss amount calculation module is used for calculating the power loss amount of the photovoltaic power station during the fault period and the power loss amount of the photovoltaic power station after the fault is removed according to the proportion of the normal operation unit, the proportion of the low-voltage ride-through unit and the proportion of the off-line unit in the photovoltaic power station.
The loss amount calculation module is used for calculating the capacity of the normally-operated unit, the capacity of the low-voltage ride-through unit and the capacity of the off-grid unit during the fault period according to the proportion of the normally-operated unit, the proportion of the low-voltage ride-through unit and the proportion of the off-grid unit in the photovoltaic power station, and calculating the power loss amount of the photovoltaic power station during the fault period and the power loss amount of the photovoltaic power station after the fault is cut according to the capacity of the normally-operated unit, the capacity of the low-voltage ride-through unit and the capacity of the off-grid unit during the fault period.
Based on the same technical solution, the present invention also discloses a computer-readable storage medium storing one or more programs, the one or more programs including instructions, which when executed by a computing device, cause the computing device to execute a photovoltaic power plant power loss amount calculation method.
Based on the same technical solution, the invention also discloses a computing device, which comprises one or more processors, one or more memories and one or more programs, wherein the one or more programs are stored in the one or more memories and configured to be executed by the one or more processors, and the one or more programs comprise instructions for executing the photovoltaic power station power loss amount computing method.
As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present invention has been described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The present invention is not limited to the above embodiments, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention are included in the scope of the claims of the present invention which are filed as the application.

Claims (10)

1. A method for calculating power loss of a photovoltaic power station is characterized by comprising the following steps:
in response to the occurrence of faults, the photovoltaic power station unit is divided into a normal operation unit, a low-voltage ride-through unit and a grid-off unit, and the proportion of the normal operation unit, the proportion of the low-voltage ride-through unit and the proportion of the grid-off unit in the photovoltaic power station are calculated according to the active current of a grid-connected point of the photovoltaic power station immediately before the occurrence of the faults, the active current of the grid-connected point of the photovoltaic power station in a steady state after the occurrence of the faults and the reactive current of the grid-connected point of the photovoltaic power station in the steady state after the occurrence of the faults;
and calculating the power loss of the photovoltaic power station during the fault period and the power loss of the photovoltaic power station after the fault is removed according to the proportion of the normal operation unit, the proportion of the low-voltage ride-through unit and the proportion of the off-grid unit in the photovoltaic power station.
2. The method for calculating the power loss of the photovoltaic power station as claimed in claim 1, wherein the proportion of the normally operating units, the proportion of the low voltage ride through units and the proportion of the off-grid units in the photovoltaic power station are calculated according to the following formula:
Figure FDA0003753433980000011
Figure FDA0003753433980000012
λ＝1-θ-η
wherein theta is the proportion of a normally operating unit in the photovoltaic power station, eta is the proportion of a low-voltage ride-through unit, lambda is the proportion of a grid-off unit, and i d _ mea Is the active current of a grid-connected point of a photovoltaic power station in a steady state after a fault occurs i q _ mea The reactive current of a grid-connected point of the photovoltaic power station in a steady state after a fault occurs, m is the total number of units of the photovoltaic power station, i d0 Active current of photovoltaic power station grid connection point immediately before fault occurrence, parameter i limit ＝1.2I N ，I N For rated current of inverter, U N Rated voltage of grid-connected point, U d Is the grid-connected point voltage in the dq coordinate,
Figure FDA0003753433980000021
set power factor angle and inverter reactive given value for normal operation
Figure FDA0003753433980000022
3. The method for calculating the power loss of the photovoltaic power station according to claim 1, wherein the calculating of the power loss of the photovoltaic power station during the fault period and the power loss of the photovoltaic power station after the fault is removed according to the proportion of the normal operation units, the proportion of the low voltage ride through units and the proportion of the off-grid units in the photovoltaic power station comprises the following steps:
calculating the capacity of the normally operating unit, the capacity of the low voltage ride through unit and the capacity of the off-grid unit during the fault period according to the proportion of the normally operating unit, the proportion of the low voltage ride through unit and the proportion of the off-grid unit in the photovoltaic power station;
and calculating the power loss of the photovoltaic power station during the fault period and the power loss of the photovoltaic power station after the fault is removed according to the capacity of the normal operation unit, the capacity of the low-voltage ride-through unit and the capacity of the off-grid unit during the fault period.
4. The method for calculating the power loss amount of the photovoltaic power station as claimed in claim 3, wherein the capacity of the normally operating units during the fault period is the product of the total number of the units of the photovoltaic power station, the unit capacity of the photovoltaic power station and the proportion of the normally operating units in the photovoltaic power station;
the capacity of the low-voltage ride-through unit in the fault period is the product of the total number of the photovoltaic power station units, the single-machine capacity of the photovoltaic power station units and the proportion of the low-voltage ride-through unit in the photovoltaic power station;
and the capacity of the off-line unit during the fault period is the product of the total number of the photovoltaic power station units, the single-machine capacity of the photovoltaic power station units and the proportion of the off-line units in the photovoltaic power station.
5. The method for calculating the power loss of the photovoltaic power station according to claim 3, wherein the calculating the power loss of the photovoltaic power station during the fault and the power loss of the photovoltaic power station after the fault is removed according to the capacity of a normal operation unit, the capacity of a low voltage ride-through unit and the capacity of an off-grid unit during the fault comprises the following steps:
according to a reactive priority principle of low voltage ride through of the photovoltaic power station, the power loss of the photovoltaic power station during the fault period is the sum of the capacity of a normal operation unit during the fault period and the capacity of a low voltage ride through unit during the fault period;
after the fault is removed, the low-voltage ride-through unit of the photovoltaic power station recovers to a normal operation state, and the power loss of the photovoltaic power station is the capacity of the off-line unit during the fault.
6. A photovoltaic power plant power loss amount calculation system, characterized by comprising:
the proportion calculation module is used for responding to the occurrence of faults, dividing the photovoltaic power station unit into a normal operation unit, a low-voltage ride-through unit and an off-line unit, and calculating the proportion of the normal operation unit, the proportion of the low-voltage ride-through unit and the proportion of the off-line unit in the photovoltaic power station according to the active current of the photovoltaic power station grid-connected point immediately before the occurrence of the faults, the active current of the photovoltaic power station grid-connected point in a steady state after the occurrence of the faults and the reactive current of the photovoltaic power station grid-connected point in the steady state after the occurrence of the faults;
and the loss amount calculation module is used for calculating the power loss amount of the photovoltaic power station during the fault period and the power loss amount of the photovoltaic power station after the fault is removed according to the proportion of the normal operation unit, the proportion of the low-voltage ride-through unit and the proportion of the off-line unit in the photovoltaic power station.
7. The system for calculating the power loss of the photovoltaic power station as recited in claim 6, wherein the formula for the proportion calculation module to calculate the proportion of the normally operating units, the proportion of the low voltage ride through units and the proportion of the off-grid units in the photovoltaic power station is as follows:
Figure FDA0003753433980000041
Figure FDA0003753433980000042
λ＝1-θ-η
wherein theta is the proportion of a normally operating unit in the photovoltaic power station, eta is the proportion of a low-voltage ride-through unit, lambda is the proportion of a grid-off unit, and i d Mea is the active current of the grid-connected point of the photovoltaic power station in a steady state after a fault occurs, i q The _Meais the reactive current of a photovoltaic power station grid-connected point in a steady state after a fault occurs, m is the total number of photovoltaic power station units, i d0 Active current of photovoltaic power station grid connection point immediately before fault occurrence, parameter i limit ＝1.2I N ，I N For rated current of inverter, U N Rated voltage for grid-connected point, U d Is the grid-connected point voltage in the dq coordinate,
Figure FDA0003753433980000043
set power factor angle and inverter reactive given value for normal operation
Figure FDA0003753433980000044
8. The system of claim 6, wherein the loss calculation is configured to calculate the capacity of the normally operating unit, the capacity of the low voltage ride through unit, and the capacity of the off-grid unit during the fault period according to the proportion of the normally operating unit, the proportion of the low voltage ride through unit, and the proportion of the off-grid unit in the photovoltaic power station, and calculate the power loss of the photovoltaic power station during the fault period and the power loss of the photovoltaic power station after the fault is removed according to the capacity of the normally operating unit, the capacity of the low voltage ride through unit, and the capacity of the off-grid unit during the fault period.
9. A computer readable storage medium storing one or more programs, wherein the one or more programs comprise instructions, which when executed by a computing device, cause the computing device to perform any of the methods of claims 1-5.
10. A computing device, comprising:
one or more processors, one or more memories, and one or more programs stored in the one or more memories and configured to be executed by the one or more processors, the one or more programs including instructions for performing any of the methods of claims 1-5.
CN202210847418.0A 2022-07-19 2022-07-19 Photovoltaic power station power loss amount calculation method and system Pending CN115344828A (en)

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