An active distribution network equivalence method and system considering unit access impedance

Abstract

The present invention discloses an active distribution network equivalent method and system that takes into account the unit access impedance, including: obtaining parameters of distributed photovoltaics in the active distribution network, and calculating equivalent parameters of distributed photovoltaic equivalent units based on the distributed photovoltaic parameters; obtaining the flow results of the active distribution network, and determining the flow data of the distributed photovoltaic equivalent units and the flow data of the load equivalent units based on the flow results; calculating the equivalent impedance of the active distribution network based on the flow data of the distributed photovoltaic equivalent units and the flow data of the load equivalent units; and constructing an active distribution network equivalent model based on the equivalent parameters and equivalent impedance of the distributed photovoltaic equivalent units. The present invention helps to solve the problem of inaccurate grid stability analysis caused by the low accuracy of the active distribution network equivalent model, improves the cognitive ability of high-proportion new energy power systems, and improves the new clean energy absorption capacity, and has high application value.

Description

Technical Field

[0001] The present invention relates to the technical field of active distribution network equivalent model simulation, and more particularly to an active distribution network equivalent method and system considering unit access impedance. Background Art

[0002] The scale of distributed photovoltaic installations within renewable energy capacity is growing rapidly. Distributed photovoltaics are typically installed in low-voltage distribution networks, where the electricity they generate is directly supplied to user loads, with excess or insufficient electricity regulated by the connected power grid. The integration of large numbers of distributed photovoltaics has led to a gradual transition from traditional passive distribution networks to more complex active distribution networks, significantly changing the load-side characteristics of the power grid. Furthermore, these distributed photovoltaics are increasingly being required to design new control strategies to improve transient performance, particularly low-voltage ride-through capability. The active distribution networks that carry these distributed photovoltaics are having an increasingly profound impact on the dynamics of the entire power system. Because the design and operation of power systems rely heavily on the accuracy of system simulation models, developing effective models to characterize actual transient characteristics is of great significance.

[0003] Studying the effects, dynamic characteristics, and impact of large-scale distributed photovoltaic integration on grid security and stability requires an active distribution network model with the same operational characteristics as the actual network. Establishing a detailed active distribution network model is the most straightforward approach. However, large power grids typically include hundreds or even thousands of active distribution networks. Simulating these networks significantly increases the scale and time required for dynamic grid simulations, making detailed modeling of each active distribution network impractical. In this context, when studying the security and stability of large power grids containing active distribution networks, one generally only needs to focus on the external impact of the active distribution network on the transmission network. In other words, there is no need to describe the internal details of the active distribution network in detail, and the original model can be appropriately simplified. Therefore, establishing an equivalent model of the active distribution network that balances computational accuracy and efficiency, while ensuring the greatest possible consistency in external characteristics, is a key issue that needs to be addressed for transient simulation of high-penetration distributed photovoltaic integration power systems and for large power grid security and stability analysis.

[0004] Faced with these challenges, existing equivalent models for active distribution networks typically connect distributed photovoltaic (PV) equivalent units directly to virtual buses connected to the loads. These units are then used to represent the aggregate transient characteristics of distributed PV within the active distribution network. These equivalent models exhibit significant error fluctuations when operating under varying operating conditions, and their accuracy is low under severe conditions. This significantly restricts the use of equivalent models for active distribution networks containing large-scale distributed PV, and limits the stable operation of future power systems dominated by renewable energy.

[0005] Therefore, an equivalent model of active distribution network considering the unit access impedance is needed. Summary of the Invention

[0006] The present invention proposes an active distribution network equivalent method and system considering unit access impedance to solve the problem of how to determine the active distribution network equivalent model.

[0007] In order to solve the above problem, according to one aspect of the present invention, a method for calculating the equivalent value of an active power distribution network taking into account the unit access impedance is provided, the method comprising:

[0008] Obtaining parameters of distributed photovoltaics in the active power distribution network, and calculating equivalent parameters of distributed photovoltaic equivalent units based on the distributed photovoltaic parameters;

[0009] Obtaining a power flow result of the active distribution network, and determining power flow data of a distributed photovoltaic equivalent unit and a load equivalent unit based on the power flow result;

[0010] Calculating the equivalent impedance of the active distribution network based on the power flow data of the distributed photovoltaic equivalent unit and the power flow data of the load equivalent unit;

[0011] An active distribution network equivalent model is constructed based on the equivalent parameters and equivalent impedances of the distributed photovoltaic equivalent units.

[0012] Preferably, the calculating of equivalent parameters of distributed photovoltaic equivalent units based on the distributed photovoltaic parameters includes:

[0013]

[0014]

[0015]

[0016]

[0017] Among them, C d,i 、C f,i and L f,i They represent the DC capacitance, AC capacitance and AC reactance of the i-th distributed photovoltaic unit before equalization; C deq 、C feq and L feq Respectively represent the equivalent DC capacitance, AC capacitance and AC reactance; N D,i represents the ratio of the capacity of the i-th distributed photovoltaic unit to the capacity of the distributed photovoltaic equivalent unit; K i represents the ride-through control parameter of the i-th distributed photovoltaic; K eq represents the control parameters of distributed photovoltaics after equalization; m represents the number of distributed photovoltaics.

[0018] Preferably, the determining of the flow data of the distributed photovoltaic equivalent unit and the flow data of the load equivalent unit based on the flow result includes:

[0019]

[0020]

[0021]

[0022]

[0023] Among them, S D,i represents the power of the i-th distributed photovoltaic unit before equalization; S Deq Represents the power of the distributed photovoltaic equivalent unit; S L,i represents the power of the i-th load before equalization; S Leq Indicates the power of the load equivalent unit; Q C,i represents the reactive power compensation of the i-th capacitor; Q Ceq Represents the reactive compensation of the capacitor equivalent unit; S Leq Indicates the power of the load equivalent unit; Q C,i Represents the reactive power compensation of the i-th capacitor; V D,i Represents the terminal voltage of the i-th distributed photovoltaic unit before equalization; I Deq represents the current of the distributed photovoltaic equivalent unit, n represents the number of loads, k represents the number of compensation capacitors; the superscript “.” represents the phasor; j represents the complex number; P Deq Represents the active power of the distributed photovoltaic equivalent unit; Q Deq Represents the reactive power of the distributed photovoltaic equivalent unit; P Leq Indicates the active power of the load equivalent unit; Q Leq Indicates the reactive power of the load equivalent unit.

[0024] Preferably, the calculating of the equivalent impedance of the active distribution network based on the flow data of the distributed photovoltaic equivalent unit and the flow data of the load equivalent unit includes:

[0025]

[0026]

[0027]

[0028]

[0029] Among them, Z eq Represents the equivalent impedance connected to the distributed photovoltaic equivalent unit in the equivalent model; S Loss Represents the network loss of the model; IDeq Represents the current of the distributed photovoltaic equivalent unit; V PCCeq Indicates the voltage at the common coupling point after equalization; I PCCeq Represents the current at the common coupling point after equalization; Z Deq Represents the equivalent impedance of the equivalent model; P Deq Represents the active power of the distributed photovoltaic equivalent unit; P Leq Indicates the active power of the load equivalent unit; Q Deq Represents the reactive power of the distributed photovoltaic equivalent unit; Q Leq Indicates the reactive power of the load equivalent unit; V PCC Represents the voltage at the common coupling point before equivalence; S PCC Indicates the voltage at the common coupling point before equivalence; S PCCeq Indicates the voltage of the common coupling point after equalization; P PCCeq represents the active power at the common coupling point in the equivalent model; Q PCCeq Represents the reactive power at the common coupling point in the equivalent model; the superscript “.” indicates a phasor; j indicates a complex number.

[0030] According to another aspect of the present invention, there is provided an active power distribution network equivalent system taking into account unit access impedance, the system comprising:

[0031] An equivalent parameter determination unit, configured to obtain parameters of distributed photovoltaics in an active power distribution network, and calculate equivalent parameters of distributed photovoltaic equivalent units based on the distributed photovoltaic parameters;

[0032] A power flow data calculation unit, configured to obtain power flow results of the active power distribution network and determine power flow data of the distributed photovoltaic equivalent unit and power flow data of the load equivalent unit based on the power flow results;

[0033] an equivalent impedance determining unit, configured to calculate the equivalent impedance of the active power distribution network based on the power flow data of the distributed photovoltaic equivalent unit and the power flow data of the load equivalent unit;

[0034] The equivalent model construction unit is used to construct an equivalent model of the active distribution network based on the equivalent parameters and equivalent impedance of the distributed photovoltaic equivalent unit.

[0035] Preferably, the equivalent parameter determination unit calculates the equivalent parameters of the distributed photovoltaic equivalent unit based on the distributed photovoltaic parameters, including:

[0036]

[0037]

[0038]

[0039]

[0040] Among them, C d,i 、C f,i and L f,i They represent the DC capacitance, AC capacitance and AC reactance of the i-th distributed photovoltaic unit before equalization; C deq 、C feq and L feq Respectively represent the equivalent DC capacitance, AC capacitance and AC reactance; N D,i represents the ratio of the capacity of the i-th distributed photovoltaic unit to the capacity of the distributed photovoltaic equivalent unit; K i represents the ride-through control parameter of the i-th distributed photovoltaic; K eq represents the control parameters of distributed photovoltaics after equalization; m represents the number of distributed photovoltaics.

[0041] Preferably, the flow data calculation unit determines the flow data of the distributed photovoltaic equivalent unit and the flow data of the load equivalent unit based on the flow result, including:

[0042]

[0043]

[0044]

[0045]

[0046] Among them, S D,i represents the power of the i-th distributed photovoltaic unit before equalization; S Deq Represents the power of the distributed photovoltaic equivalent unit; S L,i represents the power of the i-th load before equalization; S Leq Indicates the power of the load equivalent unit; Q C,i represents the reactive power compensation of the i-th capacitor; Q Ceq Represents the reactive compensation of the capacitor equivalent unit; S Leq Indicates the power of the load equivalent unit; Q C,i Represents the reactive power compensation of the i-th capacitor; V D,i Represents the terminal voltage of the i-th distributed photovoltaic unit before equalization; I Deq represents the current of the distributed photovoltaic equivalent unit, n represents the number of loads, k represents the number of compensation capacitors; the superscript “.” represents the phasor; j represents the complex number; P Deq Represents the active power of the distributed photovoltaic equivalent unit; Q Deq Represents the reactive power of the distributed photovoltaic equivalent unit; P Leq Indicates the active power of the load equivalent unit; Q LeqIndicates the reactive power of the load equivalent unit.

[0047] Preferably, the equivalent impedance determining unit calculates the equivalent impedance of the active distribution network based on the flow data of the distributed photovoltaic equivalent unit and the flow data of the load equivalent unit, including:

[0048]

[0049]

[0050]

[0051]

[0052] Among them, Z eq Represents the equivalent impedance connected to the distributed photovoltaic equivalent unit in the equivalent model; S Loss Represents the network loss of the model; I Deq Represents the current of the distributed photovoltaic equivalent unit; V PCCeq Indicates the voltage at the common coupling point after equalization; I PCCeq Represents the current at the common coupling point after equalization; Z Deq Represents the equivalent impedance of the equivalent model; P Deq Represents the active power of the distributed photovoltaic equivalent unit; P Leq Indicates the active power of the load equivalent unit; Q Deq Represents the reactive power of the distributed photovoltaic equivalent unit; Q Leq Indicates the reactive power of the load equivalent unit; V PCC Represents the voltage at the common coupling point before equivalence; S PCC Represents the voltage at the common coupling point before equivalence; S PCCeq Indicates the voltage of the common coupling point after equalization; P PCCeq represents the active power at the common coupling point in the equivalent model; Q PCCeq Represents the reactive power at the common coupling point in the equivalent model; the superscript “.” indicates a phasor; j indicates a complex number.

[0053] According to another aspect of the present invention, a computer-readable storage medium is provided, on which a computer program is stored. When the program is executed by a processor, the program implements any step of an active distribution network equivalence method considering the unit access impedance.

[0054] According to another aspect of the present invention, the present invention provides an electronic device, including:

[0055] The computer-readable storage medium described above; and

[0056] One or more processors are configured to execute the program in the computer-readable storage medium.

[0057] The present invention provides an active distribution network equivalence method and system that considers unit access impedance, including: obtaining distributed photovoltaic parameters in the active distribution network, and calculating equivalent parameters of distributed photovoltaic equivalent units based on the distributed photovoltaic parameters; obtaining the flow results of the active distribution network, and determining the flow data of the distributed photovoltaic equivalent units and the flow data of the load equivalent units based on the flow results; calculating the equivalent impedance of the active distribution network based on the flow data of the distributed photovoltaic equivalent units and the flow data of the load equivalent units; and constructing an active distribution network equivalent model based on the equivalent parameters and equivalent impedance of the distributed photovoltaic equivalent units. The present invention helps to solve the problem of inaccurate grid stability analysis caused by the low accuracy of the active distribution network equivalent model, improves the cognitive ability of high-proportion new energy power systems, and enhances the new clean energy absorption capacity, and has high application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] A more complete understanding of exemplary embodiments of the present invention may be obtained by referring to the following drawings:

[0059] Figure 1 Flowchart of an active power distribution network equivalent method 100 considering unit access impedance according to an embodiment of the present invention;

[0060] Figure 2 is a schematic diagram of a photovoltaic power generation system according to an embodiment of the present invention;

[0061] Figure 3 is a schematic diagram of an active power distribution network equivalent model according to an embodiment of the present invention;

[0062] Figure 4 is a structural diagram of a photovoltaic power generation system according to an embodiment of the present invention;

[0063] Figure 5 Schematic diagram of power change after power disturbance according to an embodiment of the present invention;

[0064] Figure 6 Schematic diagram of power change after voltage drop according to an embodiment of the present invention;

[0065] Figure 7 Schematic diagram of the structure of an active power distribution network equivalent system 700 considering the unit access impedance according to an embodiment of the present invention. DETAILED DESCRIPTION

[0066] Exemplary embodiments of the present invention will now be described with reference to the accompanying drawings. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to provide a thorough and complete disclosure of the present invention and to fully convey the scope of the present invention to those skilled in the art. The terminology used in the exemplary embodiments shown in the accompanying drawings is not intended to limit the present invention. In the accompanying drawings, identical elements are denoted by the same reference numerals.

[0067] Unless otherwise specified, the terms used herein (including technical terms) have the meanings commonly understood by those skilled in the art. In addition, it is understood that terms defined in commonly used dictionaries should be understood to have the same meanings as those in the context of the relevant fields, and should not be understood as idealized or overly formal meanings.

[0068] Figure 1 FIG. 1 is a flow chart of an active power distribution network equivalent method 100 considering the unit access impedance according to an embodiment of the present invention. Figure 1 As shown, the active distribution network equivalent method considering the unit access impedance provided by the embodiment of the present invention helps to solve the problem of inaccurate grid stability analysis caused by the low accuracy of the active distribution network equivalent model, improves the cognitive ability of high-proportion new energy power systems, and enhances the new clean energy absorption capacity, thus having high application value. The active distribution network equivalent method 100 considering the unit access impedance provided by the embodiment of the present invention begins at step 101. In step 101, the parameters of the distributed photovoltaic in the active distribution network are obtained, and the equivalent parameters of the distributed photovoltaic equivalent unit are calculated based on the distributed photovoltaic parameters.

[0069] Preferably, the calculating of equivalent parameters of distributed photovoltaic equivalent units based on the distributed photovoltaic parameters includes:

[0070]

[0071]

[0072]

[0073]

[0074] Among them, C d,i 、C f,i and L f,i They represent the DC capacitance, AC capacitance and AC reactance of the i-th distributed photovoltaic unit before equalization; C deq 、C feq and L feq Respectively represent the equivalent DC capacitance, AC capacitance and AC reactance; N D,irepresents the ratio of the capacity of the i-th distributed photovoltaic unit to the capacity of the distributed photovoltaic equivalent unit; K i represents the ride-through control parameter of the i-th distributed photovoltaic; K eq represents the control parameters of distributed photovoltaics after equalization; m represents the number of distributed photovoltaics.

[0075] The photovoltaic power generation system to which the present invention is applicable is as follows: Figure 2 As shown, the equivalent model of active distribution network is as follows Figure 3 In the present invention, the parameters of distributed photovoltaic in the active distribution network are first obtained, and the equivalent parameters of the distributed photovoltaic equivalent unit are calculated. Among them, circuit parameter aggregation and control parameter aggregation are performed for distributed photovoltaic; the circuit parameters adopt the parallel equivalent method, as shown in the following formula:

[0076]

[0077]

[0078]

[0079]

[0080] Among them, C d,i 、C f,i and L f,i They represent the DC capacitance, AC capacitance and AC reactance of the i-th distributed photovoltaic unit before equalization; C deq 、C feq and L feq Respectively represent the equivalent DC capacitance, AC capacitance and AC reactance; N D,i represents the ratio of the capacity of the i-th distributed photovoltaic unit to the capacity of the distributed photovoltaic equivalent unit; K i represents the ride-through control parameter of the i-th distributed photovoltaic; K eq represents the control parameters of distributed photovoltaics after equalization; m represents the number of distributed photovoltaics.

[0081] In step 102, a power flow result of the active power distribution network is obtained, and power flow data of the distributed photovoltaic equivalent unit and the power flow data of the load equivalent unit are determined based on the power flow result.

[0082] Preferably, the determining of the flow data of the distributed photovoltaic equivalent unit and the flow data of the load equivalent unit based on the flow result includes:

[0083]

[0084]

[0085]

[0086]

[0087] Among them, S D,i represents the power of the i-th distributed photovoltaic unit before equalization; S Deq Represents the power of the distributed photovoltaic equivalent unit; S L,i represents the power of the i-th load before equalization; S Leq Indicates the power of the load equivalent unit; Q C,i represents the reactive power compensation of the i-th capacitor; Q Ceq Represents the reactive compensation of the capacitor equivalent unit; S Leq Indicates the power of the load equivalent unit; Q C,i Represents the reactive power compensation of the i-th capacitor; V D,i Represents the terminal voltage of the i-th distributed photovoltaic unit before equalization; I Deq represents the current of the distributed photovoltaic equivalent unit, n represents the number of loads, k represents the number of compensation capacitors; the superscript “.” represents the phasor; j represents the complex number; P Deq Represents the active power of the distributed photovoltaic equivalent unit; Q Deq Represents the reactive power of the distributed photovoltaic equivalent unit; P Leq Indicates the active power of the load equivalent unit; Q Leq Indicates the reactive power of the load equivalent unit.

[0088] In this method, power flow results for the active distribution network are obtained from electromagnetic transient simulations, including the voltage and power at the point of common coupling, the power and current output by the distributed photovoltaic power generation system, and the power absorbed by the load system. Based on these power flow results, power flow data for the distributed photovoltaic equivalent unit and the load unit are calculated.

[0089] The power flow data of the distributed photovoltaic equivalent unit and the load equivalent unit are calculated in the following way:

[0090]

[0091]

[0092]

[0093]

[0094] Among them, S D,i represents the power of the i-th distributed photovoltaic unit before equalization; S Deq Represents the power of the distributed photovoltaic equivalent unit; S L,i represents the power of the i-th load before equalization; S Leq Indicates the power of the load equivalent unit; QC,i represents the reactive power compensation of the i-th capacitor; Q Ceq Represents the reactive compensation of the capacitor equivalent unit; S Leq Indicates the power of the load equivalent unit; Q C,i Represents the reactive power compensation of the i-th capacitor; V D,i Represents the terminal voltage of the i-th distributed photovoltaic unit before equalization; I Deq represents the current of the distributed photovoltaic equivalent unit, n represents the number of loads, k represents the number of compensation capacitors; the superscript “.” represents the phasor; j represents the complex number; P Deq Represents the active power of the distributed photovoltaic equivalent unit; Q Deq Represents the reactive power of the distributed photovoltaic equivalent unit; P Leq Indicates the active power of the load equivalent unit; Q Leq Indicates the reactive power of the load equivalent unit.

[0095] In step 103, the equivalent impedance of the active power distribution network is calculated based on the power flow data of the distributed photovoltaic equivalent unit and the power flow data of the load equivalent unit.

[0096] Preferably, the calculating of the equivalent impedance of the active distribution network based on the flow data of the distributed photovoltaic equivalent unit and the flow data of the load equivalent unit includes:

[0097]

[0098]

[0099]

[0100]

[0101] Among them, Z eq Represents the equivalent impedance connected to the distributed photovoltaic equivalent unit in the equivalent model; S Loss Represents the network loss of the model; I Deq Represents the current of the distributed photovoltaic equivalent unit; V PCCeq Indicates the voltage at the common coupling point after equalization; I PCCeq Represents the current at the common coupling point after equalization; Z Deq Represents the equivalent impedance of the equivalent model; P Deq Represents the active power of the distributed photovoltaic equivalent unit; P Leq Indicates the active power of the load equivalent unit; Q Deq Represents the reactive power of the distributed photovoltaic equivalent unit; Q Leq Indicates the reactive power of the load equivalent unit; V PCC Indicates the voltage at the common coupling point before equivalence; S PCCIndicates the voltage at the common coupling point before equivalence; S PCCeq Indicates the voltage of the common coupling point after equalization; P PCCeq represents the active power at the common coupling point in the equivalent model; Q PCCeq Represents the reactive power at the common coupling point in the equivalent model; the superscript “.” indicates a phasor; j indicates a complex number.

[0102] In the present invention, the equivalent power flow at the common coupling point of the active distribution network equivalent model is calculated as follows:

[0103]

[0104] The network loss of the active distribution network is calculated as follows:

[0105]

[0106]

[0107] Where V PCC Indicates the voltage at the common coupling point before equalization; V PCCeq Represents the voltage of the common coupling point after equalization; S PCC Indicates the voltage at the common coupling point before equivalence; S PCCeq Indicates the voltage of the common coupling point after equalization; P Deq Represents the active power of the distributed photovoltaic equivalent unit; P Leq Indicates the active power of the load equivalent unit; Q Deq Represents the reactive power of the distributed photovoltaic equivalent unit; Q Leq Indicates the reactive power of the load equivalent unit; I PCCeq Represents the current at the common coupling point after equalization; S Loss represents the network loss of the model; P PCCeq represents the active power at the common coupling point in the equivalent model; Q PCCeq Represents the reactive power at the point of common coupling in the equivalent model.

[0108] There are also:

[0109]

[0110] Thus we can get:

[0111]

[0112] Among them, Z Deq Represents the equivalent impedance of the equivalent model; Z eq Represents the equivalent impedance connected to the distributed photovoltaic equivalent unit in the equivalent model.

[0113] In step 104, an active power distribution network equivalent model is constructed based on the equivalent parameters and equivalent impedances of the distributed photovoltaic equivalent units.

[0114] In the present invention, an active distribution network equivalent model is constructed using the above-derived data to be equivalent to an original distribution network containing a large number of distributed photovoltaic power generation systems.

[0115] The present invention can effectively solve the problem of low accuracy of the equivalent model of the existing active distribution network due to the influence of distributed photovoltaics, but the application scenarios are not limited to this. In the active distribution network, any new energy source connected to the grid through a voltage source converter can reduce the accuracy of the equivalent model according to the present invention.

[0116] The following examples illustrate the embodiments of the present invention.

[0117] The specific implementation example of the present invention is carried out according to the following steps:

[0118] Step 1: Get Figure 4 Parameters of distributed photovoltaics in the example.

[0119] Step 2: Calculate the equivalent parameters of the distributed photovoltaic equivalent unit. According to formulas (1) to (4), the parameters of the distributed photovoltaic equivalent unit are obtained, C d =0.18F, L f =2×10 -6 H, C f =1.5×10 -5 F.

[0120] Step 3: Obtain the power flow results of the active distribution network from the electromagnetic transient simulation, including the voltage and power at the common coupling point, the power and current output by the distributed photovoltaic power generation system, and the power absorbed by the load system; as shown in Table 1.

[0121] Table 1 Line impedance and power flow in the detailed model

[0122] Subscript Z(pu) S(pu) 1,1 0.6+j0.3 -0.03-j0.015 1,2 0.8+j0.6 0.01 1,3 0.8+j0.6 -0.01-j0.005 2,1 0.6+j0.3 0.01 2,2 0.8+j0.6 -0.03-j0.015 2,3 0.8+j0.6 0.01

[0123] Step 4: Calculate the parameters of the distributed photovoltaic equivalent unit and the power flow data of the load unit based on the power flow data in step 3. The power flow data of the distributed photovoltaic is 0.03 pu, and the power flow data of the load is 0.07+j0.035 pu.

[0124] Step 5: Calculate the equivalent impedance of the active distribution network equivalent model according to step 4, Z eq The calculated value is 0.25+j0.1, Z Deq The calculated value is 0.45+j0.35.

[0125] Step 6: Construct an active distribution network equivalent model to equate an active distribution network containing a large number of distributed photovoltaic power generation systems.

[0126] According to the above implementation steps, the active distribution network equivalent modeling method considering the unit access impedance of the present invention is implemented to achieve high-precision dynamic equivalent modeling of the active distribution network.

[0127] Set different disturbances respectively. First, set the distributed photovoltaic output change condition. Figure 6 The responses of the active power distribution network detailed model, the typical equivalent model, and the equivalent model of the present invention under power output changes are shown in Figure 2. At 2.35s, the steady-state power curve of the present invention is closer to the steady-state power curve of the detailed model, and during the power recovery process, the power curve of the present invention is closer to the power curve of the detailed model in terms of both trend and value. Figure 7 Figure 3 shows the responses of the detailed model, the typical equivalent model, and the equivalent model of the present invention to a voltage sag fault. The power of the three models is similar during the fault duration, with the main difference occurring during the fault recovery phase. The active power of the detailed model recovers to a new steady-state more quickly during the recovery phase, while the typical equivalent model recovers more slowly, significantly different from the detailed model. While the curve of the present invention does not overlap with the curve of the detailed model, it is close enough.

[0128] As can be seen, the reactive power curves of the present invention closely match those of the detailed model, while the reactive power curves of the typical equivalent model differ significantly from both. The present invention is highly applicable under various operating conditions and exhibits greater robustness and accuracy than the typical equivalent model.

[0129] Figure 7 FIG. 7 is a structural diagram of an active power distribution network equivalent system 700 considering the unit access impedance according to an embodiment of the present invention. Figure 7 As shown, an active distribution network equivalent system 700 considering unit access impedance provided by an embodiment of the present invention includes: an equivalent parameter determination unit 701, a flow data calculation unit 702, an equivalent impedance determination unit 703 and an equivalent model construction unit 704.

[0130] Preferably, the equivalent parameter determination unit 701 is configured to obtain parameters of distributed photovoltaics in the active power distribution network, and calculate equivalent parameters of distributed photovoltaic equivalent units based on the distributed photovoltaic parameters.

[0131] Preferably, the equivalent parameter determining unit 701 calculates the equivalent parameters of the distributed photovoltaic equivalent unit based on the distributed photovoltaic parameters, including:

[0132]

[0133]

[0134]

[0135]

[0136] Among them, C d,i 、C f,i and L f,i They represent the DC capacitance, AC capacitance and AC reactance of the i-th distributed photovoltaic unit before equalization; C deq 、C feq and L feq Respectively represent the equivalent DC capacitance, AC capacitance and AC reactance; N D,i represents the ratio of the capacity of the i-th distributed photovoltaic unit to the capacity of the distributed photovoltaic equivalent unit; K i represents the ride-through control parameter of the i-th distributed photovoltaic; K eq represents the control parameters of distributed photovoltaics after equalization; m represents the number of distributed photovoltaics.

[0137] Preferably, the power flow data calculation unit 702 is configured to obtain power flow results of the active power distribution network, and determine power flow data of the distributed photovoltaic equivalent unit and power flow data of the load equivalent unit based on the power flow results.

[0138] Preferably, the flow data calculation unit 702 determines the flow data of the distributed photovoltaic equivalent unit and the flow data of the load equivalent unit based on the flow result, including:

[0139]

[0140]

[0141]

[0142]

[0143] Among them, S D,i represents the power of the i-th distributed photovoltaic unit before equalization; S Deq Represents the power of the distributed photovoltaic equivalent unit; S L,i represents the power of the i-th load before equalization; S Leq Indicates the power of the load equivalent unit; Q C,i represents the reactive power compensation of the i-th capacitor; Q Ceq Represents the reactive compensation of the capacitor equivalent unit; S Leq Indicates the power of the load equivalent unit; Q C,i Represents the reactive power compensation of the i-th capacitor; V D,i Represents the terminal voltage of the i-th distributed photovoltaic unit before equalization; I Deqrepresents the current of the distributed photovoltaic equivalent unit, n represents the number of loads, k represents the number of compensation capacitors; the superscript “.” represents the phasor; j represents the complex number; P Deq Represents the active power of the distributed photovoltaic equivalent unit; Q Deq Represents the reactive power of the distributed photovoltaic equivalent unit; P Leq Indicates the active power of the load equivalent unit; Q Leq Indicates the reactive power of the load equivalent unit.

[0144] Preferably, the equivalent impedance determining unit 703 is configured to calculate the equivalent impedance of the active power distribution network based on the power flow data of the distributed photovoltaic equivalent unit and the power flow data of the load equivalent unit.

[0145] Preferably, the equivalent impedance determining unit 703 calculates the equivalent impedance of the active distribution network based on the flow data of the distributed photovoltaic equivalent unit and the flow data of the load equivalent unit, including:

[0146]

[0147]

[0148]

[0149]

[0150] Among them, Z eq Represents the equivalent impedance connected to the distributed photovoltaic equivalent unit in the equivalent model; S Loss Represents the network loss of the model; I Deq Represents the current of the distributed photovoltaic equivalent unit; V PCCeq Indicates the voltage at the common coupling point after equalization; I PCCeq Represents the current at the common coupling point after equalization; Z Deq Represents the equivalent impedance of the equivalent model; P Deq Represents the active power of the distributed photovoltaic equivalent unit; P Leq Indicates the active power of the load equivalent unit; Q Deq Represents the reactive power of the distributed photovoltaic equivalent unit; Q Leq Indicates the reactive power of the load equivalent unit; V PCC Indicates the voltage at the common coupling point before equivalence; S PCC Indicates the voltage at the common coupling point before equivalence; S PCCeq Indicates the voltage of the common coupling point after equalization; P PCCeq represents the active power at the common coupling point in the equivalent model; Q PCCeq Represents the reactive power at the common coupling point in the equivalent model; the superscript “.” indicates a phasor; j indicates a complex number.

[0151] Preferably, the equivalent model construction unit 704 is configured to construct an active power distribution network equivalent model based on the equivalent parameters and equivalent impedances of the distributed photovoltaic equivalent units.

[0152] The active power distribution network equivalent system 700 considering the unit access impedance of the embodiment of the present invention corresponds to the active power distribution network equivalent method 100 considering the unit access impedance of another embodiment of the present invention, and will not be repeated here.

[0153] According to another aspect of the present invention, a computer-readable storage medium is provided, on which a computer program is stored. When the program is executed by a processor, the program implements any step of an active distribution network equivalence method considering the unit access impedance.

[0154] According to another aspect of the present invention, the present invention provides an electronic device, including:

[0155] The computer-readable storage medium described above; and

[0156] One or more processors are configured to execute the program in the computer-readable storage medium.

[0157] The present invention has been described with reference to a few embodiments. However, it is apparent to those skilled in the art that other embodiments than the ones disclosed above are equally within the scope of the present invention.

[0158] Generally, all terms used in this disclosure are to be interpreted according to their ordinary meaning in the art, unless explicitly defined otherwise herein. All references to "a / the / the [device, component, etc.]" are to be interpreted openly as referring to at least one instance of the device, component, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not necessarily need to be performed in the exact order disclosed, unless explicitly stated otherwise.

[0159] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0160] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the steps in the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0161] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0162] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0163] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the present invention.

Claims

1. An active distribution network equivalent method considering the unit access impedance, characterized in that: The method comprises: Obtaining parameters of distributed photovoltaics in the active power distribution network, and calculating equivalent parameters of distributed photovoltaic equivalent units based on the distributed photovoltaic parameters; Obtaining a power flow result of the active distribution network, and determining power flow data of a distributed photovoltaic equivalent unit and a load equivalent unit based on the power flow result; Calculating the equivalent impedance of the active distribution network based on the power flow data of the distributed photovoltaic equivalent unit and the power flow data of the load equivalent unit; Constructing an active distribution network equivalent model based on the equivalent parameters and equivalent impedance of the distributed photovoltaic equivalent unit; The step of calculating the equivalent parameters of the distributed photovoltaic equivalent unit based on the distributed photovoltaic parameters includes: Among them, C d,i 、C f,i and L f,i They represent the DC capacitance, AC capacitance and AC reactance of the i-th distributed photovoltaic unit before equalization; C deq 、C feq and L feq Respectively represent the equivalent DC capacitance, AC capacitance and AC reactance; N D ,i represents the ratio of the capacity of the i-th distributed photovoltaic unit to the capacity of the distributed photovoltaic equivalent unit; K i represents the ride-through control parameter of the i-th distributed photovoltaic; K eq represents the control parameters of distributed photovoltaic after equalization; m represents the number of distributed photovoltaic; The determining of the flow data of the distributed photovoltaic equivalent unit and the flow data of the load equivalent unit based on the flow result includes: Among them, S D,i represents the power of the i-th distributed photovoltaic unit before equalization; S Deq Represents the power of the distributed photovoltaic equivalent unit; S L,i represents the power of the i-th load before equalization; S Leq Indicates the power of the load equivalent unit; Q C,i represents the reactive power compensation of the i-th capacitor; Q Ceq Represents the reactive compensation of the capacitor equivalent unit; V D,i Represents the terminal voltage of the i-th distributed photovoltaic unit before equalization; I Deq represents the current of the distributed photovoltaic equivalent unit, n represents the number of loads, k represents the number of compensation capacitors; the superscript ". " represents the phasor; j represents the complex number; P Deq Represents the active power of the distributed photovoltaic equivalent unit; Q Deq Represents the reactive power of the distributed photovoltaic equivalent unit; P Leq Indicates the active power of the load equivalent unit; Q Leq Indicates the reactive power of the load equivalent unit; The calculating of the equivalent impedance of the active distribution network based on the flow data of the distributed photovoltaic equivalent unit and the flow data of the load equivalent unit includes: Among them, Z eq Represents the equivalent impedance connected to the distributed photovoltaic equivalent unit in the equivalent model; S Loss Represents the network loss of the model; I Deq Represents the current of the distributed photovoltaic equivalent unit; V PCCeq Indicates the voltage at the common coupling point after equalization; I PCCeq Represents the current at the common coupling point after equalization; Z Deq Represents the equivalent impedance of the equivalent model; P Deq Represents the active power of the distributed photovoltaic equivalent unit; P Leq Indicates the active power of the load equivalent unit; Q Deq Represents the reactive power of the distributed photovoltaic equivalent unit; Q Leq Indicates the reactive power of the load equivalent unit; V PCC Indicates the voltage at the common coupling point before equivalence; S PCC Indicates the voltage at the common coupling point before equivalence; S PCCeq Indicates the voltage of the common coupling point after equalization; P PCCeq represents the active power at the common coupling point in the equivalent model; Q PCCeq Represents the reactive power at the common coupling point in the equivalent model; the superscript "." indicates a phasor; j indicates a complex number.

2. An active distribution network equivalent system considering the unit access impedance, characterized in that: The system comprises: An equivalent parameter determination unit, configured to obtain parameters of distributed photovoltaics in an active power distribution network, and calculate equivalent parameters of distributed photovoltaic equivalent units based on the distributed photovoltaic parameters; A power flow data calculation unit, configured to obtain power flow results of the active power distribution network and determine power flow data of the distributed photovoltaic equivalent unit and power flow data of the load equivalent unit based on the power flow results; an equivalent impedance determining unit, configured to calculate the equivalent impedance of the active power distribution network based on the power flow data of the distributed photovoltaic equivalent unit and the power flow data of the load equivalent unit; An equivalent model construction unit, configured to construct an active distribution network equivalent model based on the equivalent parameters and equivalent impedances of the distributed photovoltaic equivalent units; The equivalent parameter determination unit calculates the equivalent parameters of the distributed photovoltaic equivalent unit based on the distributed photovoltaic parameters, including: Among them, C d,i 、C f,i and L f,i They represent the DC capacitance, AC capacitance and AC reactance of the i-th distributed photovoltaic unit before equalization; C deq 、C feq and L feq Respectively represent the equivalent DC capacitance, AC capacitance and AC reactance; N D ,i represents the ratio of the capacity of the i-th distributed photovoltaic unit to the capacity of the distributed photovoltaic equivalent unit; K i represents the ride-through control parameter of the i-th distributed photovoltaic; K eq represents the control parameters of distributed photovoltaic after equalization; m represents the number of distributed photovoltaic; The flow data calculation unit determines the flow data of the distributed photovoltaic equivalent unit and the flow data of the load equivalent unit based on the flow result, including: Among them, S D,i represents the power of the i-th distributed photovoltaic unit before equalization; S Deq Represents the power of the distributed photovoltaic equivalent unit; S L,i represents the power of the i-th load before equalization; S Leq Indicates the power of the load equivalent unit; Q C,i represents the reactive power compensation of the i-th capacitor; Q Ceq Represents the reactive compensation of the capacitor equivalent unit; V D,i Represents the terminal voltage of the i-th distributed photovoltaic unit before equalization; I Deq represents the current of the distributed photovoltaic equivalent unit, n represents the number of loads, k represents the number of compensation capacitors; the superscript ". " represents the phasor; j represents the complex number; P Deq Represents the active power of the distributed photovoltaic equivalent unit; Q Deq Represents the reactive power of the distributed photovoltaic equivalent unit; P Leq Indicates the active power of the load equivalent unit; Q Leq Indicates the reactive power of the load equivalent unit; The equivalent impedance determination unit calculates the equivalent impedance of the active distribution network based on the flow data of the distributed photovoltaic equivalent unit and the flow data of the load equivalent unit, including: Among them, Z eq Represents the equivalent impedance connected to the distributed photovoltaic equivalent unit in the equivalent model; S Loss Represents the network loss of the model; I Deq Represents the current of the distributed photovoltaic equivalent unit; V PCCeq Indicates the voltage at the common coupling point after equalization; I PCCeq Represents the current at the common coupling point after equalization; Z Deq Represents the equivalent impedance of the equivalent model; P Deq Represents the active power of the distributed photovoltaic equivalent unit; P Leq Indicates the active power of the load equivalent unit; Q Deq Represents the reactive power of the distributed photovoltaic equivalent unit; Q Leq Indicates the reactive power of the load equivalent unit; V PCC Indicates the voltage at the common coupling point before equivalence; S PCC Indicates the voltage at the common coupling point before equivalence; S PCCeq Indicates the voltage of the common coupling point after equalization; P PCCeq represents the active power at the common coupling point in the equivalent model; Q PCCeq Represents the reactive power at the common coupling point in the equivalent model; the superscript "." indicates a phasor; j indicates a complex number.

3. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of the method according to claim 1 are implemented.

4. An electronic device, characterized in that: include: The computer-readable storage medium of claim 3; as well as One or more processors are configured to execute the program in the computer-readable storage medium.

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