Distributed power supply bearing capacity assessment method and system based on multiple constraints

Abstract

The invention discloses a distributed power supply bearing capacity assessment method and system based on multiple constraints, and the method comprises the steps: firstly collecting related data of a power grid, and constructing a distributed power supply bearing capacity assessment model meeting the multiple constraints; and then the maximum accessible capacity of the distributed power supply is obtained by solving the multi-constraint-based distributed power supply bearing capacity evaluation model, and then the bearing capacity of the distributed power supply is evaluated. According to the method, when a distributed power supply bearing capacity evaluation model meeting multiple constraints is constructed, on the basis of considering voltage loss, voltage fluctuation and line current-carrying constraints, four key indexes of maximum voltage total harmonic distortion rate constraints are further considered, the harmonic problem caused by distributed power supply access is relieved to a certain extent, and the reliability of the distributed power supply bearing capacity evaluation model is improved. And the distributed power supply access capacity of the four constraint indexes at the control critical point is utilized to more comprehensively reflect the influence possibly generated after the distributed power supply is accessed to the power grid, so that the safety stability and the power supply quality of the power system are improved, and the evaluation result is ensured to be more accurate and reliable.

Description

Technical Field

[0001] The present invention belongs to the technical field of distribution network planning, and in particular relates to a method and system for evaluating the carrying capacity of distributed power sources based on multiple constraints. Background Art

[0002] With the advancement of the "dual carbon" policy and the deepening of the construction of new distribution networks, large-scale distributed renewable energy is connected to the distribution network. However, due to the volatility and intermittency of distributed energy output, a large number of harmonics are introduced when the distributed energy inverter outputs, resulting in an increase in the maximum voltage total harmonic distortion rate THD of the power system, which has an adverse impact on the stability of the distribution network, the safe operation of equipment, and power efficiency. Therefore, when evaluating the carrying capacity of distributed power sources, it is particularly important to comprehensively consider the impact of the maximum voltage total harmonic distortion rate.

[0003] The current distributed power generation capacity assessment methods mainly include two categories: detailed power flow simulation calculation and simplified assessment model. Among them, although the detailed power flow simulation calculation has high accuracy, its calculation process is complicated and time-consuming, and it is not flexible and efficient in the planning stage. The simplified assessment model often only considers factors such as voltage loss, line current, voltage fluctuation, etc., without considering the harmonic problems caused by distributed power sources, and ignoring the impact of THD on the power quality of the power grid. Summary of the invention

[0004] The purpose of the present invention is to provide a distributed power supply carrying capacity evaluation method and system based on multiple constraints in view of the above problems existing in the prior art.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] In a first aspect, the present invention proposes a distributed power supply carrying capacity evaluation method based on multiple constraints, comprising:

[0007] S1. Collect relevant data of the power grid and build a distributed power generation capacity assessment model that meets multiple constraints;

[0008] S2. Solve the distributed generation capacity assessment model based on multiple constraints to obtain the maximum accessible capacity of the distributed generation, and then evaluate the carrying capacity of the distributed generation.

[0009] In S1, the distributed power supply capacity assessment model satisfying multiple constraints includes a distributed power supply capacity assessment model satisfying the maximum voltage total harmonic distortion rate constraint;

[0010] The distributed power generation capacity assessment model that meets the maximum voltage total harmonic distortion rate constraint is:

[0011]

[0012]

[0013] In the above formula, The calculated value of the distributed generation capacity that meets the maximum voltage total harmonic distortion rate constraint, U N is the line rated voltage, G u is the voltage loss coefficient of the distributed power source corresponding to a typical load or power distribution mode, h is the harmonic current order, Z (h) is the line impedance, THD vmax is the maximum voltage total harmonic distortion rate, is the ratio of the hth harmonic current to the fundamental current, R0 and X0 are the resistance and reactance of the line under zero sequence, respectively, and x d0 is the zero-sequence reactance of the upstream power grid of the main power node of a certain line partition, n is the harmonic order, R and X are the resistance and reactance of the line respectively, and x d It is the transient reactance of the upstream power grid of the main power supply node of a certain line partition.

[0014] In S1, the distributed generation capacity assessment model that meets multiple constraints is:

[0015]

[0016] In the above formula, is the calculated value of the maximum carrying capacity of distributed power generation, To calculate the carrying capacity of distributed generation that meets the voltage loss constraint, To calculate the carrying capacity of distributed generation that meets the voltage fluctuation constraint, To calculate the carrying capacity of distributed generation that meets the line current constraints, The calculated value of the distributed generation capacity that meets the maximum voltage total harmonic distortion rate constraint.

[0017] In S1, the distributed power generation capacity assessment model that meets multiple constraints also includes a distributed power generation capacity assessment model that meets voltage loss constraints, a distributed power generation capacity assessment model that meets voltage fluctuation constraints, and a distributed power generation capacity assessment model that meets line current constraints;

[0018] The distributed power generation capacity assessment model that meets the voltage loss constraint is:

[0019]

[0020] The distributed power generation capacity assessment model that meets the voltage fluctuation constraint is:

[0021]

[0022] The distributed power generation capacity evaluation model that meets the line current constraint is:

[0023]

[0024] In the above formula, G is the calculated value of the distributed generation capacity that meets the voltage loss constraint. u is the voltage loss coefficient of the distributed power source corresponding to a typical load or power distribution mode, γ gmax is the load rate of distributed photovoltaic at the time of maximum output, P L , Q L are the active power and reactive power of the line, R and X are the resistance and reactance of the line, respectively. N is the line rated voltage, Δu is the line voltage loss, θ dg is the power factor angle of distributed photovoltaics, is the calculated value of the distributed generation capacity that meets the voltage fluctuation constraint, d b is the voltage fluctuation caused by distributed generation, λ b is the ratio of the instantaneous change in the output power of the distributed power source to the rated output power. The calculated value of the distributed generation capacity that meets the line current constraint, I im It is the continuous allowable current value of the line.

[0025] In a second aspect, the present invention proposes a distributed power supply carrying capacity assessment system based on multiple constraints, including a model building module and a model solving module;

[0026] The model building module is used to collect relevant data of the power grid and build a distributed power generation capacity assessment model that meets multiple constraints;

[0027] The model solving module is used to solve the distributed power generation carrying capacity evaluation model based on multiple constraints, obtain the maximum accessible capacity of the distributed power generation, and then evaluate the carrying capacity of the distributed power generation.

[0028] The model building module includes a model building unit that satisfies the maximum voltage total harmonic distortion rate constraint;

[0029] The maximum voltage total harmonic distortion rate constraint model construction unit is used to construct the following distributed power supply carrying capacity assessment model that satisfies the maximum voltage total harmonic distortion rate constraint:

[0030]

[0031] In the above formula, The calculated value of the distributed generation capacity that meets the maximum voltage total harmonic distortion rate constraint, U N is the line rated voltage, G uis the voltage loss coefficient of the distributed power source corresponding to a typical load or power distribution mode, h is the harmonic current order, Z (h) is the line impedance, THD vmax is the maximum voltage total harmonic distortion rate, is the ratio of the hth harmonic current to the fundamental current, R0 and X0 are the resistance and reactance of the line under zero sequence, respectively, and x d0 is the zero-sequence reactance of the upstream power grid of the main power node of a certain line partition, n is the harmonic order, R and X are the resistance and reactance of the line respectively, and x d It is the transient reactance of the upstream power grid of the main power supply node of a certain line partition.

[0032] The model building module is used to build the following distributed power generation capacity assessment model that meets multiple constraints:

[0033]

[0034] In the above formula, is the calculated value of the maximum carrying capacity of distributed power generation, To calculate the carrying capacity of distributed generation that meets the voltage loss constraint, To calculate the carrying capacity of distributed generation that meets the voltage fluctuation constraint, To calculate the carrying capacity of distributed generation that meets the line current constraints, The calculated value of the distributed generation capacity that meets the maximum voltage total harmonic distortion rate constraint.

[0035] The model construction module also includes a model construction unit that satisfies voltage loss constraints, a model construction unit that satisfies voltage fluctuation constraints, and a model construction unit that satisfies line current constraints;

[0036] The model construction unit satisfying the voltage loss constraint is used to construct the following distributed power supply carrying capacity assessment model satisfying the voltage loss constraint:

[0037]

[0038] The model construction unit satisfying the voltage fluctuation constraint is used to construct the following distributed power supply carrying capacity assessment model satisfying the voltage fluctuation constraint:

[0039]

[0040] The model construction unit satisfying the line current carrying constraint is used to construct the following distributed power supply carrying capacity assessment model satisfying the line current carrying constraint:

[0041]

[0042] In the above formula, G is the calculated value of the distributed generation capacity that meets the voltage loss constraint. u is the voltage loss coefficient of the distributed power source corresponding to a typical load or power distribution mode, γ gmax is the load rate of distributed photovoltaic at the time of maximum output, P L , Q L are the active power and reactive power of the line, R and X are the resistance and reactance of the line, respectively. N is the line rated voltage, Δu is the line voltage loss, θ dg is the power factor angle of distributed photovoltaics, is the calculated value of the distributed generation capacity that meets the voltage fluctuation constraint, d b is the voltage fluctuation caused by distributed generation, λ b is the ratio of the instantaneous change in the output power of the distributed power source to the rated output power. The calculated value of the distributed generation capacity that meets the line current constraint, I im It is the continuous allowable current value of the line.

[0043] In a third aspect, the present invention provides a distributed power supply carrying capacity assessment device based on multiple constraints, comprising a processor and a memory;

[0044] The memory is used to store computer program code and transmit the computer program code to the processor;

[0045] The processor is used to execute the aforementioned distributed power supply carrying capacity assessment method based on multiple constraints according to the instructions in the computer program code.

[0046] In a fourth aspect, the present invention provides a computer storage medium having a computer program stored thereon;

[0047] When the computer program is executed by a processor, the steps of the aforementioned method for evaluating the carrying capacity of distributed power sources based on multiple constraints are implemented.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] The present invention proposes a distributed power supply carrying capacity assessment method and system based on multiple constraints. The method first collects relevant data of the power grid and constructs a distributed power supply carrying capacity assessment model that meets multiple constraints; then, by solving the distributed power supply carrying capacity assessment model based on multiple constraints, the maximum accessible capacity of the distributed power supply is obtained, and then the carrying capacity of the distributed power supply is evaluated. On the one hand, when constructing a distributed power generation capacity assessment model that meets multiple constraints, this method not only considers voltage loss, voltage fluctuation, and line current constraints, but also further considers four key indicators of maximum voltage total harmonic distortion rate constraints, which alleviates the harmonic problem caused by the access of distributed power generation to a certain extent, and uses the four constraint indicators to control the access capacity of distributed power generation at the critical point, taking the smaller capacity as the maximum capacity of the access distribution network, which more comprehensively reflects the possible impact of distributed power generation after access to the power grid, thereby improving the safety and stability of the power system and the power supply quality, and ensuring that the assessment results are more accurate and reliable; on the other hand, this method only needs to obtain the rated voltage, maximum voltage total harmonic distortion rate, voltage loss coefficient, typical harmonic source data, line resistance and reactance of the line to be assessed, and substitutes them into the mathematical model to directly obtain the carrying capacity results of the distributed power generation. Less data is required, and there is no need to perform complex power flow calculations, which greatly shortens the calculation time, improves work efficiency, and is easy to implement and apply. It is especially suitable for the planning stage of future grids that are unclear or the scene where historical data is insufficient and needs to respond quickly to changes. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 The figure is an overall flow chart of the method of the present invention.

[0051] Figure 2 The structure diagram of the system of the present invention is shown in FIG.

[0052] Figure 3 This is a structural diagram of the device described in Example 3. DETAILED DESCRIPTION

[0053] The present invention is further described in detail below in conjunction with specific implementations and drawings.

[0054] The present invention proposes a distributed power supply capacity assessment method and system based on multiple constraints, collects relevant data of the power grid, and constructs a distributed power supply capacity assessment model that meets multiple constraints, including a distributed power supply capacity assessment model that meets the maximum voltage total harmonic distortion rate constraint, a distributed power supply capacity assessment model that meets the voltage loss constraint, a distributed power supply capacity assessment model that meets the voltage fluctuation constraint, and a distributed power supply capacity assessment model that meets the line current constraint; by solving the distributed power supply capacity assessment model based on multiple constraints, the maximum accessible capacity of the distributed power supply is obtained, and then the carrying capacity of the distributed power supply is evaluated. The method takes into account four key indicators: voltage loss, voltage fluctuation, line current and maximum voltage total harmonic distortion rate, and uses the distributed power supply access capacity of the four constraint indicators at the control critical point, taking the smaller value of the capacity as the maximum capacity of the access distribution network, more comprehensively reflecting the possible impact of the distributed power supply on the power grid after access, and ensuring that the assessment result is more accurate and reliable.

[0055] Embodiment 1:

[0056] like Figure 1 As shown, a distributed power generation capacity evaluation method based on multiple constraints is carried out in the following steps:

[0057] 1. Collect relevant data of the power grid and build a distributed power generation capacity assessment model that meets multiple constraints;

[0058] Collect basic parameter data such as conductor model, voltage level, trunk length, resistance per unit length, reactance per unit length, active power, reactive power, load distribution along the line, distributed power generation power factor, and distributed power generation fluctuation coefficient of the medium-voltage line in the power grid of the area to be evaluated, and collect current spectrum data of harmonic sources in the area to be evaluated;

[0059] The distributed generation capacity assessment model that meets multiple constraints is:

[0060]

[0061] In the above formula, is the calculated value of the maximum carrying capacity of distributed power generation, To calculate the carrying capacity of distributed generation that meets the voltage loss constraint, To calculate the carrying capacity of distributed generation that meets the voltage fluctuation constraint, To calculate the carrying capacity of distributed generation that meets the line current constraints, The calculated value of the distributed generation capacity that meets the maximum voltage total harmonic distortion rate constraint;

[0062] Among them, the distributed power generation capacity assessment model that meets multiple constraints includes the distributed power generation capacity assessment model that meets the maximum voltage total harmonic distortion rate constraint, the distributed power generation capacity assessment model that meets the voltage loss constraint, the distributed power generation capacity assessment model that meets the voltage fluctuation constraint, and the distributed power generation capacity assessment model that meets the line current constraint;

[0063] Harmonics are sinusoidal components in the power grid whose frequencies are integer multiples of the fundamental wave. Their presence in the power system can lead to a series of adverse effects, such as increasing the loss of transformers and transmission lines, reducing equipment life, and interfering with communication equipment.

[0064] The current spectra of different harmonic sources are collected, as shown in Tables 1 and 2;

[0065] Table 1 Harmonic current spectrum of 12-pulse inverter

[0066]

[0067] Table 2 Harmonic current spectrum of YG inverter

[0068]

[0069] Assuming that the harmonic source is only distributed photovoltaic, and the distributed photovoltaic is gradually distributed, the short-circuit capacity on the power supply side is 260MVA, based on the voltage loss coefficient method corresponding to a typical load or power distribution mode of distributed power supply, the simplified calculation formula of the total harmonic distortion rate of the maximum voltage of the line can be expressed as:

[0070]

[0071] in,

[0072]

[0073] In summary, the distributed generation capacity assessment model that meets the maximum voltage total harmonic distortion rate constraint is:

[0074]

[0075] The distributed power generation capacity assessment model that meets the voltage loss constraint is:

[0076]

[0077] The distributed power generation capacity assessment model that meets the voltage fluctuation constraint is:

[0078]

[0079] The distributed power generation capacity evaluation model that meets the line current constraint is:

[0080]

[0081] In the above formula, THD v is the voltage harmonic distortion rate, I N，dg is the rated current of the distributed photovoltaic line, G u is the voltage loss coefficient of the distributed generation corresponding to a typical load or power distribution mode, reflecting the relative loss of voltage loss of different distribution modes relative to the terminal concentrated distribution mode. The typical load or power distribution modes mainly include terminal concentrated distribution, uniform distribution, increasing distribution, decreasing distribution and intermediate heavy distribution, with values ​​of 1, 0.5, 0.67, 0.33 and 0.5 respectively. h is the harmonic current order, Z (h) is the line impedance, U N is the line rated voltage, in kV, is the ratio of the hth harmonic current to the fundamental current, which can be obtained from actual measurements or typical harmonic source data. R0 and X0 are the resistance and reactance of the line under zero sequence, respectively. d0 is the zero-sequence reactance of the upstream power grid of the main power node of a certain line partition, n is the harmonic order, R and X are the resistance and reactance of the line respectively, in Ω, x d For a certain line partition main power supply node, such as a hub node, the transient reactance of the upper power grid, The calculated value of the distributed generation capacity to meet the maximum voltage total harmonic distortion rate constraint, THD vmax is the maximum voltage total harmonic distortion rate. According to the distribution network planning and design regulations, for example, 10kV is 4%. is the calculated value of the distributed generation capacity that meets the voltage loss constraint, γ gmax is the load rate of distributed photovoltaic at the time of maximum output, P L , Q L are the active power and reactive power of the line respectively, Δu is the line voltage loss, the unit is pu, a positive value indicates a voltage drop, a negative value indicates a voltage increase, θ dg is the power factor angle of distributed photovoltaics, is the calculated value of the distributed generation capacity that meets the voltage fluctuation constraint, d b is the voltage fluctuation caused by distributed power supply, in pu, λ b is the ratio of the instantaneous change in the output power of the distributed power source to the rated output power, which is set to 0.5. The calculated value of the distributed generation capacity that meets the line current constraint, I im It is the continuous allowable current value of the line, that is, the allowable current carrying capacity of the line, and the unit is A.

[0082] 2. Solve the distributed power generation capacity assessment model based on multiple constraints to obtain the maximum accessible capacity of the distributed power generation, and then evaluate the carrying capacity of the distributed power generation;

[0083] According to relevant technical guidelines, determine reasonable critical values ​​of various constraints, including the maximum voltage total harmonic distortion rate of 4%, the voltage loss control value of 5%, and the voltage fluctuation control value of 3%. Combined with the conductor cross-section, select the maximum continuous allowable current of the line, such as 380A for LGJ-120, 445A for LGJ-150, 515A for LGJ-185, and 610A for LGJ-240;

[0084] The maximum allowable distributed photovoltaic installed capacity under different harmonic sources, line models and trunk length scenarios is shown in Table 3:

[0085] Table 3 Maximum allowable distributed photovoltaic installed capacity under different harmonic sources, line models and trunk lengths Unit: MW

[0086]

[0087] The distributed power generation capacity assessment model that meets the voltage loss constraint, the distributed power generation capacity assessment model that meets the line current constraint, the distributed power generation capacity assessment model that meets the voltage fluctuation constraint, and the distributed power generation capacity assessment model that meets the maximum voltage total harmonic distortion rate constraint are respectively used to calculate the capacity of the distributed power generation under each constraint, and the minimum value is taken as the final capacity of the distributed power generation. The results are shown in Table 4:

[0088] Table 4 Final bearing capacity results

[0089]

[0090]

[0091] Embodiment 2:

[0092] like Figure 2 As shown, a distributed power generation capacity assessment system based on multiple constraints includes a model building module and a model solving module;

[0093] The model building module is used to collect relevant data of the power grid and build a distributed power generation capacity assessment model that meets multiple constraints;

[0094] The model solving module is used to solve the distributed power generation carrying capacity evaluation model based on multiple constraints, obtain the maximum accessible capacity of the distributed power generation, and then evaluate the carrying capacity of the distributed power generation.

[0095] The model building module is used to build the following distributed power generation capacity assessment model that meets multiple constraints:

[0096]

[0097] In the above formula, is the calculated value of the maximum carrying capacity of distributed power generation, To calculate the carrying capacity of distributed generation that meets the voltage loss constraint, To calculate the carrying capacity of distributed generation that meets the voltage fluctuation constraint, To calculate the carrying capacity of distributed generation that meets the line current constraints, The calculated value of the distributed generation capacity that meets the maximum voltage total harmonic distortion rate constraint.

[0098] The model building module includes a model building unit that satisfies the maximum voltage total harmonic distortion rate constraint;

[0099] The maximum voltage total harmonic distortion rate constraint model construction unit is used to construct the following distributed power supply carrying capacity assessment model that satisfies the maximum voltage total harmonic distortion rate constraint:

[0100]

[0101] In the above formula, The calculated value of the distributed generation capacity that meets the maximum voltage total harmonic distortion rate constraint, U N is the line rated voltage, G u is the voltage loss coefficient of the distributed power source corresponding to a typical load or power distribution mode, h is the harmonic current order, Z (h) is the line impedance, THD vmax is the maximum voltage total harmonic distortion rate, is the ratio of the hth harmonic current to the fundamental current, R0 and X0 are the resistance and reactance of the line under zero sequence, respectively, and x d0 is the zero-sequence reactance of the upstream power grid of the main power node of a certain line partition, n is the harmonic order, R and X are the resistance and reactance of the line respectively, and x d It is the transient reactance of the upstream power grid of the main power supply node of a certain line partition.

[0102] The model construction module also includes a model construction unit that satisfies voltage loss constraints, a model construction unit that satisfies voltage fluctuation constraints, and a model construction unit that satisfies line current constraints;

[0103] The model construction unit satisfying the voltage loss constraint is used to construct the following distributed power supply carrying capacity assessment model satisfying the voltage loss constraint:

[0104]

[0105] The model construction unit satisfying the voltage fluctuation constraint is used to construct the following distributed power supply carrying capacity assessment model satisfying the voltage fluctuation constraint:

[0106]

[0107] The model construction unit satisfying the line current carrying constraint is used to construct the following distributed power supply carrying capacity assessment model satisfying the line current carrying constraint:

[0108]

[0109] In the above formula, G is the calculated value of the distributed generation capacity that meets the voltage loss constraint. u is the voltage loss coefficient of the distributed power source corresponding to a typical load or power distribution mode, γ gmax is the load rate of distributed photovoltaic at the time of maximum output, P L , Q L are the active power and reactive power of the line, R and X are the resistance and reactance of the line, respectively. N is the line rated voltage, Δu is the line voltage loss, θ dg is the power factor angle of distributed photovoltaics, is the calculated value of the distributed generation capacity that meets the voltage fluctuation constraint, d b is the voltage fluctuation caused by distributed generation, λ b is the ratio of the instantaneous change in the output power of the distributed power source to the rated output power. The calculated value of the distributed generation capacity that meets the line current constraint, I im It is the continuous allowable current value of the line.

[0110] Embodiment 3:

[0111] like Figure 3 As shown, a distributed power supply carrying capacity assessment device based on multiple constraints includes a processor and a memory;

[0112] The memory is used to store computer program code and transmit the computer program code to the processor;

[0113] The processor is used to execute a distributed power supply carrying capacity assessment method based on multiple constraints described in Example 1 according to the instructions in the computer program code.

[0114] Embodiment 4:

[0115] A computer storage medium having a computer program stored thereon;

[0116] When the computer program is executed by the processor, the steps of a distributed power supply carrying capacity assessment method based on multiple constraints described in this solution are implemented.

Claims

1. A distributed power generation capacity assessment method based on multiple constraints, characterized in that: The method comprises: S1. Collect relevant data of the power grid and build a distributed power generation capacity assessment model that meets multiple constraints; S2. Solve the distributed generation capacity assessment model based on multiple constraints to obtain the maximum accessible capacity of the distributed generation, and then evaluate the carrying capacity of the distributed generation.

2. According to the multi-constraint distributed power supply carrying capacity evaluation method of claim 1, it is characterized in that: In S1, the distributed power generation capacity assessment model satisfying multiple constraints includes a distributed power generation capacity assessment model satisfying the maximum voltage total harmonic distortion rate constraint; The distributed power generation capacity assessment model that meets the maximum voltage total harmonic distortion rate constraint is: In the above formula, The calculated value of the distributed generation capacity that meets the maximum voltage total harmonic distortion rate constraint, U N is the line rated voltage, G u is the voltage loss coefficient of the distributed power source corresponding to a typical load or power distribution mode, h is the harmonic current order, Z (h) is the line impedance, THD vmax is the maximum voltage total harmonic distortion rate, is the ratio of the hth harmonic current to the fundamental current, R0 and X0 are the resistance and reactance of the line under zero sequence, respectively, and x d0 is the zero-sequence reactance of the upstream power grid of the main power node of a certain line partition, n is the harmonic order, R and X are the resistance and reactance of the line respectively, and x d It is the transient reactance of the upstream power grid of the main power supply node of a certain line partition.

3. The method for evaluating the carrying capacity of distributed power sources based on multiple constraints according to claim 1 is characterized in that: In S1, the distributed generation capacity assessment model that meets multiple constraints is: In the above formula, is the calculated value of the maximum carrying capacity of distributed power generation, To calculate the carrying capacity of distributed generation that meets the voltage loss constraint, To calculate the carrying capacity of distributed generation that meets the voltage fluctuation constraint, To calculate the carrying capacity of distributed generation that meets the line current constraints, The calculated value of the distributed generation capacity that meets the maximum voltage total harmonic distortion rate constraint.

4. The method for evaluating the carrying capacity of distributed power sources based on multiple constraints according to claim 1 is characterized in that: In S1, the distributed power generation capacity assessment model that meets multiple constraints also includes a distributed power generation capacity assessment model that meets voltage loss constraints, a distributed power generation capacity assessment model that meets voltage fluctuation constraints, and a distributed power generation capacity assessment model that meets line current constraints; The distributed power generation capacity assessment model that meets the voltage loss constraint is: The distributed power generation capacity assessment model that meets the voltage fluctuation constraint is: The distributed power generation capacity evaluation model that meets the line current constraint is: In the above formula, G is the calculated value of the distributed generation capacity that meets the voltage loss constraint. u is the voltage loss coefficient of the distributed power source corresponding to a typical load or power distribution mode, γ gmax is the load rate of distributed photovoltaic at the time of maximum output, P L , Q L are the active power and reactive power of the line, R and X are the resistance and reactance of the line, respectively. N is the line rated voltage, Δu is the line voltage loss, θ dg is the power factor angle of distributed photovoltaics, is the calculated value of the distributed generation capacity that meets the voltage fluctuation constraint, d b is the voltage fluctuation caused by distributed generation, λ b is the ratio of the instantaneous change in the output power of the distributed power source to the rated output power. The calculated value of the distributed generation capacity that meets the line current constraint, I im It is the continuous allowable current value of the line.

5. A distributed power generation capacity assessment system based on multiple constraints, characterized in that: The system includes a model building module and a model solving module; The model building module is used to collect relevant data of the power grid and build a distributed power generation capacity assessment model that meets multiple constraints; The model solving module is used to solve the distributed power generation carrying capacity evaluation model based on multiple constraints, obtain the maximum accessible capacity of the distributed power generation, and then evaluate the carrying capacity of the distributed power generation.

6. The distributed power generation capacity assessment system based on multiple constraints according to claim 5 is characterized in that: The model building module includes a model building unit that satisfies the maximum voltage total harmonic distortion rate constraint; The maximum voltage total harmonic distortion rate constraint model construction unit is used to construct the following distributed power supply carrying capacity assessment model that satisfies the maximum voltage total harmonic distortion rate constraint: In the above formula, The calculated value of the distributed generation capacity that meets the maximum voltage total harmonic distortion rate constraint, U N is the line rated voltage, G u is the voltage loss coefficient of the distributed power source corresponding to a typical load or power distribution mode, h is the harmonic current order, Z (h) is the line impedance, THD vmax is the maximum voltage total harmonic distortion rate, is the ratio of the hth harmonic current to the fundamental current, R0 and X0 are the resistance and reactance of the line under zero sequence, respectively, and x d0 is the zero-sequence reactance of the upstream power grid of the main power node of a certain line partition, n is the harmonic order, R and X are the resistance and reactance of the line respectively, and x d It is the transient reactance of the upstream power grid of the main power supply node of a certain line partition.

7. The distributed power generation capacity assessment system based on multiple constraints according to claim 5 is characterized in that: The model building module is used to build the following distributed power generation capacity assessment model that meets multiple constraints: In the above formula, is the calculated value of the maximum carrying capacity of distributed power generation, To calculate the carrying capacity of distributed generation that meets the voltage loss constraint, To calculate the carrying capacity of distributed generation that meets the voltage fluctuation constraint, To calculate the carrying capacity of distributed generation that meets the line current constraints, The calculated value of the distributed generation capacity that meets the maximum voltage total harmonic distortion rate constraint.

8. The distributed power generation capacity assessment system based on multiple constraints according to claim 5 is characterized in that: The model construction module also includes a model construction unit that satisfies voltage loss constraints, a model construction unit that satisfies voltage fluctuation constraints, and a model construction unit that satisfies line current constraints; The model construction unit satisfying the voltage loss constraint is used to construct the following distributed power supply carrying capacity assessment model satisfying the voltage loss constraint: The model construction unit satisfying the voltage fluctuation constraint is used to construct the following distributed power supply carrying capacity assessment model satisfying the voltage fluctuation constraint: The model construction unit satisfying the line current carrying constraint is used to construct the following distributed power supply carrying capacity assessment model satisfying the line current carrying constraint: In the above formula, G is the calculated value of the distributed generation capacity that meets the voltage loss constraint. u is the voltage loss coefficient of the distributed power source corresponding to a typical load or power distribution mode, γ gmax is the load rate of distributed photovoltaic at the time of maximum output, P L , Q L are the active power and reactive power of the line, R and X are the resistance and reactance of the line, respectively. N is the line rated voltage, Δu is the line voltage loss, θ dg is the power factor angle of distributed photovoltaics, is the calculated value of the distributed generation capacity that meets the voltage fluctuation constraint, d b is the voltage fluctuation caused by distributed generation, λ b is the ratio of the instantaneous change in the output power of the distributed power source to the rated output power. The calculated value of the distributed generation capacity that meets the line current constraint, I im It is the continuous allowable current value of the line.

9. A distributed power generation capacity assessment device based on multiple constraints, characterized in that: including a processor and a memory; The memory is used to store computer program code and transmit the computer program code to the processor; The processor is used to execute a distributed power generation capacity assessment method based on multiple constraints as described in any one of claims 1 to 4 according to instructions in the computer program code.

10. A computer storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of a distributed power generation capacity assessment method based on multiple constraints described in any one of claims 1 to 4 are implemented.

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