A power control-based distributed photovoltaic grid-connected simulation method and system

Abstract

The application provides a power control-based distributed photovoltaic grid-connected simulation method and system, comprising: obtaining relevant parameters, wherein the relevant parameters comprise voltage drop identification values, a drop slope, a recovery slope and a generator tripping time; inputting the relevant parameters into a power control-based distributed photovoltaic model, wherein when the voltage at a distributed photovoltaic grid-connected point drops to the voltage drop identification values, the model enters a voltage drop working condition; after entering the voltage drop working condition, active power decreases according to the drop slope; after entering the voltage drop working condition for more than the generator tripping time, distributed photovoltaic generator tripping is performed; after entering the voltage drop working condition, the distributed photovoltaic grid-connected point voltage is recovered according to the recovery slope within a specified time. The power grid fine simulation considering the low-voltage ride-through characteristics of the distributed photovoltaic is realized.

Description

Technical Field

[0001] This invention belongs to the field of distributed photovoltaic grid connection technology, and particularly relates to a distributed photovoltaic grid connection simulation method and system based on power control. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] As the scale of distributed photovoltaic (PV) grid connection continues to increase, the accuracy of the previous model of incorporating distributed PV into the load side for grid simulation analysis has been greatly reduced. This makes it impossible to guarantee the accuracy of grid simulation analysis calculations and ensure the safe and stable operation of the grid. Summary of the Invention

[0004] To address the technical problems mentioned above, this invention provides a distributed photovoltaic grid-connected simulation method and system based on power control, which can accurately simulate the grid-connected characteristics of distributed photovoltaic based on power control and achieve refined grid simulation considering the low-voltage ride-through characteristics of distributed photovoltaic.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] The first aspect of this invention provides a distributed photovoltaic grid-connected simulation method based on power control, comprising:

[0007] Obtain relevant parameters, including voltage drop identification value, drop slope, recovery slope, and switching time;

[0008] The relevant parameters are input into a power-controlled distributed photovoltaic (PV) model. When the voltage at the PV grid connection point drops to the voltage drop identification value, the model enters a voltage drop condition. After entering the voltage drop condition, the active power decreases according to the stated drop slope. If the voltage drop condition exceeds the stated tripping time, the distributed PV is tripped. After entering the voltage drop condition, the PV returns to normal within a specified time, and the voltage at the PV grid connection point recovers according to the stated recovery slope.

[0009] Furthermore, the voltage drop identification value and the drop slope can be several, with each voltage drop identification value corresponding to a drop slope;

[0010] The model, through multiple settings, enters a voltage drop condition when the voltage at the distributed photovoltaic grid connection point drops to a certain voltage drop identification value; after entering the voltage drop condition, the active power decreases according to the decrease slope corresponding to the voltage drop identification value.

[0011] Furthermore, the active power decreases according to the slope, which is achieved through a comparison circuit, a controllable switch circuit, a division operation circuit, an integration circuit, two addition and limit value circuits, and a multiplication operation circuit connected in sequence.

[0012] Furthermore, the cutting time can be several;

[0013] The model uses multiple settings to perform distributed photovoltaic power generation after a voltage drop condition exceeds a certain power generation time.

[0014] Furthermore, the distributed photovoltaic power generation switchover is achieved based on the switchover time through a comparison stage, a delay stage, and a multiplication stage connected in sequence.

[0015] Furthermore, the method for restoring the voltage at the distributed photovoltaic grid connection point according to the recovery slope is specifically implemented by, based on the recovery slope and a voltage drop identification value, through a comparison stage, two controllable switch stages, a division operation stage, an integration stage, two addition and limit value stages, and a multiplication operation stage connected in sequence.

[0016] A second aspect of the present invention provides a distributed photovoltaic grid-connected simulation system based on power control, comprising:

[0017] The parameter acquisition module is configured to acquire relevant parameters, including voltage drop identification values, drop slope, recovery slope, and switching time.

[0018] The simulation module is configured to: input relevant parameters into a power-controlled distributed photovoltaic (PV) model; when the voltage at the PV grid connection point drops to the voltage drop identification value, the model enters a voltage drop condition; after entering the voltage drop condition, the active power decreases according to the stated decrease slope; after the voltage drop condition exceeds the stated tripping time, the distributed PV is tripped; after entering the voltage drop condition, the voltage recovers to normal within a specified time, and the voltage at the PV grid connection point recovers according to the stated recovery slope.

[0019] Furthermore, the voltage drop identification value and the drop slope can be several, with each voltage drop identification value corresponding to a drop slope;

[0020] The model, through multiple settings, enters a voltage drop condition when the voltage at the distributed photovoltaic grid connection point drops to a certain voltage drop identification value; after entering the voltage drop condition, the active power decreases according to the decrease slope corresponding to the voltage drop identification value.

[0021] A third aspect of the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the power control-based distributed photovoltaic grid-connected simulation method described above.

[0022] A fourth aspect of the present invention provides a computer device including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the steps in the power control-based distributed photovoltaic grid-connected simulation method described above.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] This invention provides a power control-based distributed photovoltaic grid-connected simulation method, which can accurately simulate the grid-connected characteristics of power control-based distributed photovoltaics and realize refined grid simulation considering the low-voltage ride-through characteristics of distributed photovoltaics. Attached Figure Description

[0025] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0026] Figure 1 This is a partial flowchart of a distributed photovoltaic grid-connected simulation method based on power control according to Embodiment 1 of the present invention;

[0027] Figure 2 This is a partial flowchart of a distributed photovoltaic grid-connected simulation method based on power control according to Embodiment 1 of the present invention;

[0028] Figure 3 This is a simulation result diagram of Embodiment 1 of the present invention, showing that the voltage drop at the grid connection point of a distributed photovoltaic system does not exceed a specified time.

[0029] Figure 4 This is a simulation result diagram of the voltage drop at the grid connection point of a distributed photovoltaic system exceeding a specified time, according to Embodiment 1 of the present invention. Detailed Implementation

[0030] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0031] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0032] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0033] Example 1

[0034] This embodiment provides a distributed photovoltaic grid-connected simulation method based on power control, including the following steps:

[0035] Step 1: Obtain the relevant parameters input by the user (recovery slope, several voltage drop identification values, and the drop slope and switching time corresponding to each voltage drop identification value), specifically including: the first voltage drop identification value V, the second voltage drop identification value V2, the drop slopes T(0.85pu) and T(0.5pu) corresponding to different voltage drop identification values, the recovery slope T(recovery), and the switching times T0.85qieji and T0.5qieji corresponding to different voltage drop identification values.

[0036] Step 2: Input the relevant parameters into the distributed photovoltaic model based on power control. When the voltage at the distributed photovoltaic grid connection point drops to the voltage drop identification value, the model enters the voltage drop condition. After entering the voltage drop condition, the active power decreases according to the decreasing slope. After the voltage drop condition exceeds the tripping time, the distributed photovoltaic is tripped. After entering the voltage drop condition, the voltage returns to normal within a specified time, and the voltage at the distributed photovoltaic grid connection point recovers according to the recovery slope. Specifically: This model can modify the voltage dip identification value according to the actual grid-connected characteristics of distributed photovoltaic (PV) systems. When the voltage at the PV grid connection point drops to this value, the system enters a voltage dip condition, meaning the distributed PV system transitions from steady-state operation to voltage dip condition, and its control characteristics also change accordingly. This model can also modify the power reduction rate during the voltage dip at the PV grid connection point, enabling active power to decrease at a specified rate during this period. Furthermore, the model can set different reduction rates for different voltage dip levels based on the actual grid-connected characteristics of the distributed PV system, thereby controlling the power output during the voltage dip. Accurate simulation of control characteristics: This model can modify the distributed photovoltaic (PV) tripping time according to the actual grid-connected characteristics of distributed PV. After the voltage drop at the PV grid connection point exceeds a certain range for a specified time, the model can implement the PV tripping function. Simultaneously, this model can set different tripping times for different voltage drop levels according to the actual grid-connected characteristics of distributed PV, thereby achieving accurate simulation of the tripping characteristics caused by voltage drops. This model can also modify the distributed PV power recovery rate according to the actual grid-connected characteristics of distributed PV. After the voltage at the PV grid connection point returns to normal within a specified time, the distributed PV will recover according to that specified rate, thereby achieving accurate simulation of the power control characteristics during the voltage recovery period of distributed PV.

[0037] As one implementation method, a distributed photovoltaic model is established based on the user-defined module of PSASP, and input and output modules are built. By controlling the output current, the distributed photovoltaic model can control the distributed photovoltaic power, thereby realizing the interactive function between this model and the PSASP software simulation operation.

[0038] Specifically, such as Figure 1 and Figure 2 As shown, it includes:

[0039] (1) There can be several voltage sag identification values ​​and descent slopes, with each voltage sag identification value corresponding to a descent slope. The model, through multiple settings, enters a voltage sag condition when the voltage at the distributed photovoltaic grid connection point drops to a certain voltage sag identification value. After entering the voltage sag condition, the active power decreases according to the descent slope corresponding to that voltage sag identification value. In this embodiment, the active power decreases at a specified rate during the voltage sag at the distributed photovoltaic grid connection point. The decrease in active power according to the descent slope is achieved through a comparison circuit, a controllable switch circuit, a division operation circuit, an integration circuit, two addition and limit circuits (i.e., an addition operation circuit and a limit circuit connected in sequence), and a multiplication circuit.

[0040] The first voltage drop identification value V (0.85) set by the user is obtained through the first assignment step 2, and the first voltage drop identification value V is transmitted to the first comparison step (COMP).

[0041] The first comparison step 1 obtains the distributed photovoltaic grid connection point voltage (bus voltage VT), and calculates the first comparison result based on the bus voltage VT and the first voltage drop identification value V. Specifically, when the bus voltage VT is less than or equal to the first voltage drop identification value V, the output is 1 and the voltage drop condition is entered; otherwise, the output is 0, and the first comparison result is transmitted to the first controllable switch.

[0042] In the second assignment step 4, the first descent slope T (0.85pu) set by the user is obtained and transmitted to the first controllable switch.

[0043] The first controllable switch 3 stores a first threshold interval [A, B), where A and B are set to 0.5 and 1.5 respectively. Based on the first comparison result and the first descent slope T (0.85pu), the output result of the first controllable switch is obtained. If the first comparison result is within the range of [A, B), the output result of the first controllable switch is the first descent slope T (0.85pu) output by the second assignment stage. Otherwise, the output is 0, and the output result of the first controllable switch is transmitted to the first division operation stage.

[0044] In the third assignment step 6, the first constant (-1) set by the user is obtained and the first constant (-1) is transmitted to the first division operation step.

[0045] The first division operation stage 5 is based on the first constant (-1) and the output result of the first controllable switch. Specifically, the first constant (-1) is used as x1 and the output result of the first controllable switch is used as x2 to perform division operation, obtain the division operation result y, and transmit it to the first integration stage.

[0046] Specifically, the division operation is as follows: when x2 ≠ 0, y = x1 / x2; otherwise, y = 0.

[0047] The first integration stage 7 performs integration based on the division result output by the first division stage. Specifically, the division result output by the first division stage is used as x1 in the integration operation to obtain the integration result y, which is then transmitted to the second controllable switch.

[0048] Specifically, the integration operation is as follows:

[0049]

[0050]

[0051] When y≥Y max When y = Y max

[0052] When y≤Y min When y = Y min

[0053] Among them, parameters D, K, Ymax, and Ymin are all manually set, and △t represents the time interval.

[0054] In the fourth assignment step 24, the second voltage drop identification value V2 (0.5) set by the user is obtained, and the second voltage drop identification value V2 is transmitted to the second comparison step.

[0055] The second comparison step 23 obtains the bus voltage VT and calculates the second comparison result based on the bus voltage VT and the second voltage drop identification value V2. Specifically, when the bus voltage VT is less than or equal to the second voltage drop identification value V2, the output is 1, otherwise the output is 0, and the second comparison result is transmitted to the second controllable switch and the third controllable switch.

[0056] In the fifth assignment step 26, the second descent slope T (0.5pu) set by the user is obtained and transmitted to the third controllable switch;

[0057] The third controllable switch 25 stores a first threshold interval [A, B), where A and B are set to 0.5 and 1.5 respectively. Based on the second comparison result and the second descent slope T (0.5pu), the output result of the third controllable switch is obtained. If the second comparison result is within the range of [A, B), the output result of the third controllable switch is the second descent slope T (0.5pu), otherwise the output is 0, and the output result of the third controllable switch is transmitted to the second division operation stage.

[0058] In the sixth assignment step 28, the second constant (-1) set by the user is obtained and the second constant (-1) is transmitted to the second division operation step;

[0059] The second division operation stage 27 is based on the second constant (-1) and the output result of the third controllable switch. Specifically, the second constant (-1) is used as x1 and the output result of the third controllable switch is used as x2 to perform division operation, obtain the division operation result, and transmit it to the second integration stage.

[0060] The second integration stage 29 performs integration based on the division result output by the second division stage. Specifically, the division result output by the second division stage is used as x1 in the integration operation to obtain the integration result y, which is then transmitted to the first addition stage.

[0061] The second controllable switch 34 stores a first threshold interval [A, B), where A and B are set to 0.5 and 1.5 respectively. Based on the integral operation result output by the first integration stage and the second comparison result output by the second comparison stage, the output result of the second controllable switch is obtained. Specifically, if the second comparison result output by the second comparison stage is within the range [A, B), the output result of the second controllable switch is 0. Otherwise, the output result of the second controllable switch is the integral operation result output by the first integration stage, and the output result of the second controllable switch is transmitted to the first addition stage.

[0062] In the seventh assignment step 9, the user-defined third constant (1) is obtained and transmitted to the first addition operation step;

[0063] The first addition operation stage 8 performs a weighted summation operation based on the integral operation result output by the second integration stage, the third constant (1) output by the seventh assignment stage, and the second controllable switch output result output by the second controllable switch, to obtain the output result y of the first addition operation stage. Specifically, the integral operation result output by the second integration stage, the third constant (1) output by the seventh assignment stage, and the second controllable switch output result output by the second controllable switch are respectively used as xi for the weighted summation operation and transmitted to the first limit stage.

[0064] The weighted summation operation is specifically as follows: Here, Ai is a parameter set manually.

[0065] The first limit step 11, based on the output result of the first addition operation step, uses the output result of the first addition operation step as the value transformation x1 to obtain the result y of the active power decreasing at a specified rate during the voltage drop of the distributed photovoltaic grid connection point (this result is the proportion of active power decrease), and transmits it to the third addition operation step.

[0066] Specifically, the value transformation is as follows:

[0067] When y ≥ Ymax, y = Ymax

[0068] When y ≤ Ymin, y = Ymin

[0069] Other cases: y = xI

[0070] Among them, Ymin and Ymax are parameters that are set manually.

[0071] (2) After the voltage at the grid-connected point of the distributed photovoltaic system returns to normal within a specified time, it is restored at a specified rate. The method for restoring the voltage at the grid-connected point of the distributed photovoltaic system according to the recovery slope is as follows: based on the recovery slope and a voltage drop identification value, it is achieved through a comparison circuit, two controllable switches, a division operation circuit, an integration circuit, two addition and limit circuits (i.e., an addition operation circuit and a limit circuit connected in sequence), and a multiplication operation circuit.

[0072] In the eighth assignment step 41, the first voltage drop identification value V set by the user is obtained and transmitted to the third comparison step.

[0073] The third comparison step 40 obtains the bus voltage VT and calculates the third comparison result based on the bus voltage VT and the first voltage drop identification value V. Specifically, when the bus voltage VT is greater than or equal to the first voltage drop identification value V, the output is 1, otherwise the output is 0, and the third comparison result is transmitted to the fourth controllable switch.

[0074] The fourth controllable switch 55 stores a second threshold interval [A, B), where A and B are set to 1 and 9999999 respectively. Based on the third comparison result output by the third comparison step, the output result of the fourth controllable switch is obtained. Specifically, if the output result of the third addition operation step is within the range of [A, B), the output result of the fourth controllable switch is 0. Otherwise, the output is the third comparison result output by the third comparison step, and the output result of the fourth controllable switch is transmitted to the fifth controllable switch.

[0075] In the ninth assignment step 43, the user-defined recovery slope T (recovery) is obtained and transmitted to the fifth controllable switch;

[0076] The fifth controllable switch 42 stores the third threshold interval [A, B), where A and B are set to 0.5 and 1.5 respectively. Based on the output result of the fourth controllable switch and the recovery slope T (recovery) output of the ninth assignment stage, the output result of the fifth controllable switch is obtained. Specifically, if the output result of the fourth controllable switch is within the range of [A, B), the output result of the fifth controllable switch is the recovery slope T (recovery) output of the ninth assignment stage; otherwise, the output is 0, and the output result of the fifth controllable switch is transmitted to the third division operation stage.

[0077] In the tenth assignment step 45, the fourth constant (1) set by the user is obtained and the fourth constant (1) is transmitted to the third division operation step;

[0078] The third division operation stage 44 is based on the fourth constant (1) and the output result of the fifth controllable switch. Specifically, the fourth constant (1) is taken as x1 and the output result of the fifth controllable switch is taken as x2. The division operation is performed to obtain the division operation result y, which is then transmitted to the third integration stage.

[0079] The third integration stage 46 performs integration based on the division result output by the third division stage to obtain the integration result. Specifically, the division result output by the first division stage is used as x1 in the integration operation to obtain the integration result y, which is then transmitted to the second addition stage.

[0080] In the eleventh assignment step 48, the expandable unit parameters are obtained and transmitted to the second addition operation step;

[0081] The second addition operation stage 47 performs a weighted summation operation based on the expandable unit parameters output by the eleventh assignment stage and the integral operation result output by the third integration stage to obtain the output result of the second addition operation stage, which is then transmitted to the second limit stage.

[0082] The second limiting step 49, based on the output result of the second addition step, uses the output result of the second addition step as x1 for value transformation to obtain the output result y (power recovery ratio) of the second limiting step, and transmits it to the third addition step.

[0083] The third addition operation step 53 performs a weighted summation operation based on the output results of the second limit step and the first limit step to obtain the output result of the third addition operation step, which is then transmitted to the third limit step and the fourth controllable switch.

[0084] The third limit value link 54, based on the output result of the third addition operation link, uses the output result of the third addition operation link as x1 for value transformation, obtains the output result y of the third limit value link, and transmits it to the first multiplication operation link. (3) The generator tripping time can be several; through multi-channel setting, after entering the voltage dip condition and exceeding a certain generator tripping time, distributed photovoltaic generator tripping is performed. In this embodiment, to implement the function of distributed photovoltaic connection point voltage dip for a certain range exceeding the specified time and then performing distributed photovoltaic generator tripping, through two-way setting, different generator tripping times can be set for different voltage dip degrees. Among them, for distributed photovoltaic generator tripping, based on the generator tripping time, it is realized through a comparison link, a delay link, and a multiplication operation link connected in sequence.

[0085] The twelfth assignment link 57 obtains the fifth constant set by the user (i.e., the first voltage dip identification value 0.85), and transmits the fifth constant (0.85) to the fourth comparison link;

[0086] The fourth comparison link 56 obtains the bus voltage VT, and based on the bus voltage VT and the fifth constant (0.85), calculates the fourth comparison result. Specifically, when the bus voltage VT is less than or equal to the fifth constant (0.85), the output is 1, otherwise the output is 0, and transmits the fourth comparison result to the first delay link and the second multiplication operation link;

[0087] The first delay link 58, based on the fourth comparison result, obtains the delay result and transmits it to the second multiplication operation link. Specifically, it stores the first generator tripping time T0.85qieji. Let the moment when the input starts to be greater than 0 be t0 (i.e., the moment when the fourth comparison result starts to be greater than 0 is t0), then when t < t0 + the first generator tripping time, the output is 0; otherwise the output is 1.

[0088] The second multiplication operation link 59 performs a multiplication operation based on the delay result output by the first delay link and the fourth comparison result output by the fourth comparison link, obtains the second multiplication result, and performs generator tripping (TPG) based on the second multiplication result, and transmits it to the oscilloscope 60 and the second delay link;

[0089] Among them, the multiplication operation is specifically: taking the inputs as xi respectively, setting the parameter A, and the result of the multiplication operation is

[0090] The second delay link 62, based on the second multiplication result output by the second multiplication operation link, obtains the delay result and transmits it to the fifth comparison link. Specifically, it stores the expandable unit parameter. Let the moment when the input starts to be greater than 0 be t0 (i.e., the moment when the second multiplication result starts to be greater than 0 is t0), then when t < t0 + the expandable unit parameter, the output is 0; otherwise the output is 1, and outputs to the fifth comparison link.

[0091] The thirteenth assignment step 63 obtains the sixth constant (0.5, for comparison, and has nothing to do with the voltage dip value) set by the user, and transmits the sixth constant (0.5) to the fifth comparison step;

[0092] The fifth comparison step 61 calculates the fifth comparison result based on the sixth constant (0.5) output by the thirteenth assignment step and the delay result output by the second delay step. Specifically, when the delay result is less than or equal to the sixth constant (0.5), the output is 1; otherwise, the output is 0, and the fifth comparison result is transmitted to the first multiplication operation step;

[0093] The fourteenth assignment step 65 obtains the seventh constant (i.e., the second voltage dip identification value 0.5) set by the user, and transmits the seventh constant (0.5) to the fourth comparison step;

[0094] The sixth comparison step 64 obtains the bus voltage VT, and calculates the sixth comparison result based on the bus voltage VT and the seventh constant (0.5). Specifically, when the bus voltage VT is less than or equal to the seventh constant (0.5), the output is 1; otherwise, the output is 0, and the sixth comparison result is transmitted to the third delay step and the third multiplication operation step;

[0095] The third delay step 66 obtains the delay result based on the sixth comparison result and transmits it to the third multiplication operation step. Specifically, the internal memory stores the second generator tripping time T0.5qieji. Let the moment when the input starts to be greater than 0 be t0 (i.e., the moment when the sixth comparison result starts to be greater than 0 is t0). Then, when t < t0 + the second generator tripping time, the output is 0; otherwise, the output is 1.

[0096] The third multiplication operation step 67 performs a multiplication operation based on the delay result output by the third delay step and the sixth comparison result output by the sixth comparison step to obtain the third multiplication result, and performs generator tripping TPG based on the third multiplication result and transmits it to the oscilloscope 68 and the fourth delay step.

[0097] The fourth delay step 69 obtains the delay result based on the third multiplication result output by the third multiplication operation step and transmits it to the seventh comparison step. Specifically, the internal expandable unit parameter is set. Let the moment when the input starts to be greater than 0 be t0 (i.e., the moment when the third multiplication result starts to be greater than 0 is t0). Then, when t < t0 + the expandable unit parameter, the output is 0; otherwise, the output is 1.

[0098] The fifteenth assignment step 71 obtains the eighth constant (0.5, for comparison, and has nothing to do with the voltage dip value) set by the user, and transmits the eighth constant (0.5) to the seventh comparison step;

[0099] The seventh comparison step 70 calculates the seventh comparison result based on the eighth constant (0.5) output by the fifteenth assignment step and the delay result output by the fourth delay step. Specifically, when the delay result is less than or equal to the eighth constant (0.5), the output is 1, otherwise the output is 0, and the seventh comparison result is transmitted to the first multiplication operation step.

[0100] The first multiplication operation stage 10 obtains the initial value of active power (PGO) as input, and combines the seventh comparison result output by the seventh comparison stage, the fifth comparison result output by the fifth comparison stage, and the result output by the third limit stage to perform multiplication operation, obtain the first multiplication result (active power after decreasing at different slopes, or voltage recovery result of distributed photovoltaic grid connection point), and transmits it to the fourth division operation stage. (4) Realizes the sending of current commands from power control to PSASP operation. The model can obtain the real part and imaginary part of the current based on the active power after decreasing at different slopes or voltage recovery result of distributed photovoltaic grid connection point:

[0101] In the fourth division operation step 12, the bus voltage VT is obtained. Based on the bus voltage VT and the first multiplication result, specifically, the first multiplication result is used as x1 and the bus voltage VT is used as x2. The division operation is performed to obtain the division result and transmit it to the fourth limit step.

[0102] The fourth limit step 13, based on the division operation result, uses the division operation result as the value transformation x1 to obtain the output result of the fourth limit step, which is then transmitted to the sixth and seventh multiplication steps;

[0103] In the sixteenth assignment step 21, the user-defined ninth constant (0.017453) is obtained and transmitted to the fourth multiplication step;

[0104] In the fourth multiplication step 20, the bus voltage phase angle (ANGB) is obtained and multiplied in conjunction with the ninth constant (0.017453) to obtain the fourth multiplication result, which is then transmitted to the cosine function step.

[0105] Cosine function step 16 calculates the cosine result based on the result of the fourth multiplication and transmits it to the sixth multiplication step;

[0106] The sixth multiplication step 14 performs a multiplication operation based on the cosine result and the fourth multiplication result output by the fourth limit step to obtain the sixth multiplication result, namely the real part ITR of the current, and transmits it to the oscilloscope 38.

[0107] In the seventeenth assignment step 19, the tenth constant (0.017453) set by the user is obtained and transmitted to the fifth multiplication step;

[0108] In the fifth multiplication step 18, ANGB is obtained and combined with the tenth constant (0.017453) to perform multiplication operations, obtain the fifth multiplication result, and transmit it to the sine function step.

[0109] Sine function step 17 calculates the sine result based on the result of the fifth multiplication and transmits it to the seventh multiplication step;

[0110] The seventh multiplication step 15 performs a multiplication operation based on the sine result and the output result of the fourth limit step to obtain the seventh multiplication result, namely the imaginary part ITI of the current, and transmits it to the oscilloscope 39.

[0111] A simulation job was built based on PSASP, setting up a voltage dip fault condition, and implementing interaction between this model and the PSASP software simulation job. The simulation results were presented when the voltage dip at the distributed photovoltaic grid connection point did not exceed a specified time. Figure 3 As shown in the simulation results, when the voltage drop at the distributed photovoltaic grid connection point exceeds a specified time, the results are as follows: Figure 4 As shown. (Through) Figure 3 , Figure 4 It can be seen that the model of the present invention can accurately simulate the power control characteristics of distributed photovoltaics when the voltage drop does not exceed the specified time, and cut off the power when the voltage drop exceeds the specified time.

[0112] This invention establishes a power-controlled distributed photovoltaic (PV) model based on PSASP software. The model primarily includes: considering the practical application scenarios of distributed PV and the power control characteristics of large-scale distributed PV controllers during low-voltage ride-through, a power-controlled distributed PV model is built using PSASP software. During voltage dips at the grid connection point of the distributed PV, the model can be configured to reduce power at a specified rate, with this rate corresponding to the degree of voltage dip. If the voltage dip at the grid connection point exceeds a certain range for a specified time, the distributed PV will be disconnected by the system, and this specified time can be set to different values ​​for different voltage dip levels. After the voltage at the grid connection point of the distributed PV returns to normal within a specified time, the distributed PV will recover at a specified rate. This model can accurately simulate the grid-connected characteristics of distributed PV based on power control, achieving refined grid simulation that considers the low-voltage ride-through characteristics of distributed PV.

[0113] Example 2

[0114] This embodiment provides a distributed photovoltaic grid-connected simulation system based on power control, which specifically includes the following modules:

[0115] The parameter acquisition module is configured to acquire relevant parameters, including voltage drop identification values, drop slope, recovery slope, and switching time.

[0116] The simulation module is configured to: input relevant parameters into a power-controlled distributed photovoltaic (PV) model; when the voltage at the PV grid connection point drops to the voltage drop identification value, the model enters a voltage drop condition; after entering the voltage drop condition, the active power decreases according to the stated decrease slope; after the voltage drop condition exceeds the stated tripping time, the distributed PV is tripped; after entering the voltage drop condition, the voltage recovers to normal within a specified time, and the voltage at the PV grid connection point recovers according to the stated recovery slope.

[0117] It should be noted that each module in this embodiment corresponds one-to-one with each step in Embodiment 1, and their specific implementation processes are the same, so they will not be repeated here.

[0118] Example 3

[0119] This embodiment provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps in the power control-based distributed photovoltaic grid-connected simulation method described in Embodiment 1 above.

[0120] Example 4

[0121] This embodiment provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the steps in the power control-based distributed photovoltaic grid-connected simulation method described in Embodiment 1 above.

[0122] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of hardware embodiments, software embodiments, or embodiments combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage and optical storage) containing computer-usable program code.

[0123] This invention is 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 block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can 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, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0124] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0125] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0126] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), or random access memory (RAM), etc.

[0127] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A simulation method for distributed photovoltaic grid connection based on power control, characterized in that, include: Obtain relevant parameters, including voltage drop identification value, drop slope, recovery slope, and switching time; The relevant parameters are input into the distributed photovoltaic model based on power control. When the voltage at the grid connection point of the distributed photovoltaic system drops to the voltage drop identification value, the model enters the voltage drop condition. After entering the voltage drop condition, the active power decreases according to the drop slope. Distributed photovoltaic power generation is performed after the voltage drop condition exceeds the specified power-off time. After entering the voltage drop condition, the voltage returns to normal within a specified time, and the voltage at the distributed photovoltaic grid connection point recovers according to the recovery slope. The voltage drop identification value and the drop slope are several, and each voltage drop identification value corresponds to a drop slope; The model, through multiple settings, enters the voltage drop condition when the voltage at the distributed photovoltaic grid connection point drops to a certain voltage drop identification value; After entering the voltage sag condition, the active power decreases according to the sag slope corresponding to the voltage sag identification value.

2. The distributed photovoltaic grid-connected simulation method based on power control as described in claim 1, characterized in that, The active power decreases according to the slope, which is achieved through a comparison circuit, a controllable switch circuit, a division operation circuit, an integration circuit, two addition and limit circuits, and a multiplication operation circuit connected in sequence.

3. The distributed photovoltaic grid-connected simulation method based on power control as described in claim 1, characterized in that, The cutting time is several; The model uses multiple settings to perform distributed photovoltaic power generation after a voltage drop condition exceeds a certain power generation time.

4. The distributed photovoltaic grid-connected simulation method based on power control as described in claim 1, characterized in that, The distributed photovoltaic power generation switchover is achieved by sequentially connecting a comparison stage, a delay stage, and a multiplication stage, based on the power generation switchover time.

5. The distributed photovoltaic grid-connected simulation method based on power control as described in claim 1, characterized in that, The method for restoring the voltage at the grid-connected point of the distributed photovoltaic system according to the recovery slope is specifically implemented by using the recovery slope and a voltage drop identification value as a basis, through a comparison stage, two controllable switch stages, a division operation stage, an integration stage, two addition and limit value stages, and a multiplication operation stage connected in sequence.

6. A distributed photovoltaic grid-connected simulation system based on power control, characterized in that, include: The parameter acquisition module is configured to acquire relevant parameters, including voltage drop identification values, drop slope, recovery slope, and switching time. The simulation module is configured to: input relevant parameters into a power-controlled distributed photovoltaic model, which enters a voltage drop condition when the voltage at the distributed photovoltaic grid connection point drops to the voltage drop identification value; after entering the voltage drop condition, the active power decreases according to the drop slope. Distributed photovoltaic power generation is performed after the voltage drop condition exceeds the specified power-off time. After entering the voltage drop condition, the voltage returns to normal within a specified time, and the voltage at the distributed photovoltaic grid connection point recovers according to the recovery slope. The voltage drop identification value and the drop slope are several, and each voltage drop identification value corresponds to a drop slope; The model, through multiple settings, enters the voltage drop condition when the voltage at the distributed photovoltaic grid connection point drops to a certain voltage drop identification value; After entering the voltage sag condition, the active power decreases according to the sag slope corresponding to the voltage sag identification value.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the steps in the power control-based distributed photovoltaic grid-connected simulation method as described in any one of claims 1-5.

8. A computer device comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that, When the processor executes the program, it implements the steps in the power control-based distributed photovoltaic grid-connected simulation method as described in any one of claims 1-5.

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