Method and system for determining reactive power demand of new energy sources to maintain voltage level at grid connection point

Abstract

The present invention discloses a method and system for determining reactive power demand of a new energy source for maintaining the voltage level at a grid connection point, including: determining an initial value of the initial reactive power demand based on the voltage phase angle, short-circuit ratio, and impedance ratio when the initial reactive power demand is zero; determining the voltage phase angle when the initial reactive power demand is the initial value; determining a corrected reactive power demand based on the voltage phase angle when the initial reactive power demand is the initial value; calculating the absolute value of the difference between the corrected reactive power demand and the initial value; when the absolute value is greater than or equal to a set threshold, using the corrected reactive power demand as the initial value of the initial reactive power demand, re-determining the voltage phase angle and corrected reactive power demand until the absolute value of the difference between the corrected reactive power demand and the initial value is less than the set threshold; and determining the reactive power demand of the new energy grid-connected system based on the corrected reactive power demand when the absolute value is less than the set threshold. This method achieves accurate calculation of the reactive power demand of the new energy grid-connected system.

Description

Technical Field

[0001] The present invention relates to the field of new energy grid connection technology, and in particular to a method and system for determining new energy reactive power demand to maintain a voltage level at a grid connection point. Background Art

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

[0003] With the rapid development of new energy represented by wind power and photovoltaics, traditional power systems are gradually transforming into high-proportion new energy power systems, and static voltage stability problems are gradually emerging.

[0004] When determining the reactive power demand of renewable energy, the existing method only determines it through the reactive power flow equation of the renewable energy grid-connected system and the output power of the renewable energy, without considering the impact of the error generated in the process of solving the voltage phase angle on the reactive power demand, resulting in a large error in the determined reactive power demand. Summary of the Invention

[0005] In order to solve the above problems, the present invention proposes a method and system for determining the reactive power demand of new energy sources to maintain the voltage level at the grid connection point. By continuously calculating the voltage phase angle and reactive power demand, accurate calculation of the reactive power demand of the system is achieved.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] First, a method for determining the reactive power demand of renewable energy sources to maintain the voltage level at the grid connection point is proposed, including:

[0008] Obtain the short-circuit ratio and impedance ratio of the new energy grid-connected system;

[0009] According to the short-circuit ratio and impedance ratio, the voltage phase angle when the initial reactive power demand is zero is calculated;

[0010] Determine the initial value of the initial reactive power demand according to the voltage phase angle, short circuit ratio and impedance ratio when the initial reactive power demand is zero;

[0011] Determine the voltage phase angle when the initial reactive power demand is the initial value;

[0012] Determine the corrected reactive power demand based on the voltage phase angle when the initial reactive power demand is the initial value;

[0013] Calculate the absolute value of the difference between the corrected reactive power demand and the initial value;

[0014] When the absolute value is greater than or equal to the set threshold, the corrected reactive power demand is used as the initial value of the initial reactive power demand, and the voltage phase angle and the corrected reactive power demand are re-determined until the absolute value of the difference between the corrected reactive power demand and the initial value is less than the set threshold;

[0015] The reactive power demand of the new energy grid-connected system is determined according to the corrected reactive power demand when the absolute value is less than the set threshold.

[0016] Secondly, a new energy reactive power demand determination system for maintaining the voltage level at the grid connection point is proposed, including:

[0017] Data acquisition module, used to obtain the short-circuit ratio and impedance ratio of the new energy grid-connected system;

[0018] The reactive power demand initial value acquisition module is used to calculate the voltage phase angle when the initial reactive power demand is zero based on the short-circuit ratio and the impedance ratio; and determine the initial value of the initial reactive power demand based on the voltage phase angle, the short-circuit ratio and the impedance ratio when the initial reactive power demand is zero;

[0019] The modified reactive power demand acquisition module is used to determine the voltage phase angle when the initial reactive power demand is the initial value; and determine the modified reactive power demand according to the voltage phase angle when the initial reactive power demand is the initial value;

[0020] The reactive power demand correction module is used to calculate the absolute value of the difference between the corrected reactive power demand and the initial value; when the absolute value is greater than or equal to a set threshold, the corrected reactive power demand is used as the initial value of the initial reactive power demand, and the voltage phase angle and the corrected reactive power demand are re-determined until the absolute value of the difference between the corrected reactive power demand and the initial value is less than the set threshold;

[0021] The system reactive power demand determination module is used to determine the reactive power demand of the renewable energy grid-connected system based on the corrected reactive power demand when the absolute value is less than the set threshold.

[0022] In a third aspect, an electronic device is proposed, comprising a memory and a processor, and computer instructions stored in the memory and running on the processor. When the computer instructions are run by the processor, the steps described in the method for determining the reactive power demand of new energy to maintain the voltage level of the grid connection point are completed.

[0023] In a fourth aspect, a computer-readable storage medium is proposed for storing computer instructions. When the computer instructions are executed by a processor, the steps of the method for determining the reactive power demand of new energy for maintaining the voltage level of the grid connection point are completed.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The present invention realizes the correction of the reactive power demand of the system by continuously calculating the voltage phase angle and reactive power demand, thereby obtaining accurate reactive power demand.

[0026] 2. The present invention can more accurately calculate the reactive power demand of new energy sources based only on the short-circuit ratio information and impedance ratio information at the grid connection point, thereby guiding the configuration of reactive power compensation capacity in new energy stations and simplifying the calculation method.

[0027] Advantages of additional aspects of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The drawings in the specification, which constitute a part of this application, are used to provide further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute improper limitations on this application.

[0029] Figure 1 This is a flow chart of the method disclosed in Example 1;

[0030] Figure 2 Analyze the model for the single feed-in system of renewable energy;

[0031] Figure 3 Analyze models for renewable energy multi-feed systems;

[0032] Figure 4 A new energy single feed system model was built;

[0033] Figure 5 The calculation result of reactive power demand when the renewable energy penetration rate is 30%;

[0034] Figure 6 The reactive power demand calculation result when the renewable energy penetration rate is 40%;

[0035] Figure 7 The reactive power demand calculation result when the renewable energy penetration rate is 50%;

[0036] Figure 8 To build a new energy multi-feedback system model;

[0037] Figure 9 Calculation results of reactive power demand for renewable energy multi-feed systems with different renewable energy penetration rates. DETAILED DESCRIPTION

[0038] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0039] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0040] Example 1

[0041] In this embodiment, a method for determining the reactive power demand of new energy sources to maintain the voltage level at the grid connection point is disclosed, such as Figure 1 As shown, including:

[0042] S1: Obtain the short-circuit ratio and impedance ratio of the new energy grid-connected system.

[0043] The new energy grid-connected system includes a new energy single-feed system and a new energy multi-feed system. According to the type of the grid-connected system, the short-circuit ratio and impedance ratio of the corresponding type of system are obtained.

[0044] Among them, the short-circuit ratio and impedance ratio of the renewable energy single-infeed system and the impedance ratio of the renewable energy multi-infeed system are directly obtained.

[0045] For the renewable energy multi-feed system, the self-impedance of node i, the mutual impedance between node i and node j, and the original complex power injected by node j are calculated. and the original injected complex power of node i The equivalent short-circuit ratio of node i is calculated and obtained. The equivalent short-circuit ratio of node i is the short-circuit ratio of node i, thereby obtaining the short-circuit ratio of the renewable energy multi-feed system.

[0046] According to Thevenin's theorem, the renewable energy multi-infeed system can be regarded as the superposition of the AC system and the renewable energy system. The constructed renewable energy multi-infeed system analysis model is as follows: Figure 3 shown.

[0047] Figure 3 middle is the node voltage of the synchronous unit, is the node voltage of the new energy unit, Inject current into the synchronous machine node, Inject current into new energy nodes, is the node voltage of the new energy unit when the synchronous machine acts alone, It is the node voltage of the new energy unit when the new energy unit acts alone.

[0048] exist Figure 3 In the AC system in (b), the node voltage of the synchronous unit is:

[0049]

[0050] Where U ac is the node voltage vector of the synchronous unit, Z is the impedance matrix of the system, I ac is the current vector injected by the synchronous machine node. At this time, the current vector injected by the new energy node is 0.

[0051] The short-circuit capacity S provided by the AC system to the new energy node i ac,i for:

[0052]

[0053] Where, E eq,i is the open circuit voltage of new energy node i, U N is the rated voltage of the new energy source, Z ii is the self-impedance of node i in the system impedance matrix.

[0054] exist Figure 3 In the new energy system in (c), the voltage of the new energy node is:

[0055]

[0056] Where ΔU is the node voltage change vector caused by the new energy injection power, I E is the current vector injected by the new energy node. At this time, the current vector injected by the synchronous machine node is 0.

[0057] The voltage change of node i caused by the injection power of new energy node is:

[0058]

[0059] Where, is the i-th element of the node voltage vector ΔU in equation (3), is the self-impedance of node i in the system impedance matrix, is the mutual impedance between node i and node j in the system impedance matrix, are the injected currents of new energy nodes i and j respectively.

[0060] If the effect of the power injected by other new energy nodes on the voltage of node i is converted into the effect of the additional power of node i itself on the voltage of node i, then the equivalent grid-connected capacity of node i can be obtained after transformation as follows:

[0061]

[0062] Where, is the equivalent grid-connected capacity of node i, P eq,i is the equivalent active power of node i, P eq,i =P i +ΔP i , ΔP i is the additional active power of node i, P i is the active power generated by the renewable energy of node i, Q eq,i is the equivalent reactive power of node i, Q eq,i =Q i +ΔQ i , Q i is the reactive power generated by the renewable energy source at node i, ΔQi is the additional reactive power of node i, is the equivalent injected current of node i, is the original injected complex power of node i, is the additional complex power of node i, ΔP i is the additional active power of node i, ΔQ i is the additional reactive power of node i.

[0063] The ratio of the short-circuit capacity of node i to the equivalent grid-connected capacity is the equivalent short-circuit ratio of node i. Combining equations (2) and (6), the equivalent short-circuit ratio SCR of node i is obtained. i , the equivalent short circuit ratio is the short circuit ratio of node i, the equivalent short circuit ratio SCR i for:

[0064]

[0065] The process of calculating the short-circuit ratio of node i in the new energy multi-feed system in this embodiment is as follows:

[0066] Get the self-impedance of node i from the system impedance matrix Mutual impedance between node i and node j and the original complex power injected into node j

[0067] According to the self-impedance of node i Mutual impedance between node i and node j and the original injected complex power of node j Through formula (5) Calculate the additional active power ΔP of node i i and the additional reactive power ΔQ of node i i .

[0068] The additional active power ΔP of node i is obtained according to the calculation i , additional reactive power ΔQ of node i i , using formula (5) Calculate the additional complex power of node i

[0069] The additional complex power of node i is obtained by calculation and the original injected complex power of node i The equivalent grid-connected capacity of node i is calculated using formula (5):

[0070] Equivalent grid-connected capacity obtained based on calculation Using formula (6), the equivalent short-circuit ratio of node i is calculated, which is the short-circuit ratio of node i.

[0071] S2: Calculate the voltage phase angle when the initial reactive power demand is zero based on the short-circuit ratio and the impedance ratio; determine the initial value of the initial reactive power demand based on the voltage phase angle, the short-circuit ratio, and the impedance ratio when the initial reactive power demand is zero.

[0072] In specific implementation, the voltage phase angle is determined according to the short-circuit ratio, impedance ratio and voltage phase angle calculation model;

[0073] The initial reactive power demand is determined based on the voltage phase angle, short-circuit ratio, impedance ratio and initial reactive power demand calculation model.

[0074] The renewable energy grid-connected system includes a renewable energy single-feed system and a renewable energy multi-feed system. According to the Thevenin theorem, a renewable energy single-feed system is constructed, such as Figure 2 shown.

[0075] Figure 2 Where E is the terminal voltage amplitude of the equivalent power source, U is the voltage amplitude at the renewable energy access point, θ is the voltage phase angle at the renewable energy access point, Z is the line impedance, R is the line resistance, X is the line reactance, I is the line transmission current, S is the complex power generated by the renewable energy source, P is the active power generated by the renewable energy source, and Q is the reactive power generated by the renewable energy source. The model ignores the influence of line admittance.

[0076] For renewable energy grid-connected systems, whether they are single-feed systems or multi-feed systems, the reactive power flow equation at the grid connection point, the system voltage drop formula, and the impedance ratio formula are the same.

[0077] The reactive power flow equation at the grid connection point is:

[0078]

[0079] The system pressure drop formula is:

[0080]

[0081] The impedance ratio formula of the system is:

[0082] α=X / R (9)

[0083] Where α is the impedance ratio.

[0084] However, the short-circuit ratio equations for single-infeed systems and multi-infeed systems are different.

[0085] The short-circuit ratio equation of the renewable energy single-feed system is:

[0086]

[0087] Where, E is the open circuit voltage of the new energy node, U Nis the rated voltage of the new energy source, Z is the line impedance, and in the actual system, it is the self-impedance of the PCC point in the system impedance matrix.

[0088] Substitute equations (10) and (9) into equations (7) and (8), and take the voltage base value U B =U N , power base value S B =S=P, normalize equations (7) and (8), take E=1 approximately, and let U=E, we can get:

[0089]

[0090]

[0091] Where Q is the initial reactive power demand of the single-infeed system.

[0092] Wherein, Equation (11) is the initial reactive power demand calculation model of the single-infeed system, and Equation (12) is the voltage phase angle calculation model of the single-infeed system.

[0093] For a single-infeed system, the short-circuit ratio and impedance ratio of the single-infeed system are obtained by S1 and substituted into Equation (12) to calculate the voltage phase angle when the initial reactive power demand is zero.

[0094] Substitute the voltage phase angle, short-circuit ratio, and impedance ratio when the initial reactive power demand is zero into equation (11) to calculate the initial value of the initial reactive power demand, which is recorded as Q1.

[0095] For the renewable energy multi-feed system, the short-circuit ratio equation of the renewable energy multi-feed system is formula (6). Substitute formulas (6) and (9) into formulas (7) and (8), and take the voltage base value U B =U N , power base value S B =S eq,i , normalize equations (7) and (8) and take E eq,i =1, and let U i =E eq,i , we can get:

[0096]

[0097]

[0098] Wherein, formula (13) is the initial reactive power demand calculation model of the multi-infeed system, and formula (14) is the voltage phase angle calculation model of the multi-infeed system. eq is the initial reactive power demand of the multi-infeed system, P eq is the equivalent active power of the multi-infeed system, is the sum of the active power generated by the renewable energy and the additional active power, and the subscript i is omitted in Equations (13) and (14).

[0099] The short-circuit ratio and impedance ratio of the multi-infeed system are obtained by S1 and substituted into Equation (14) to calculate the voltage phase angle when the initial reactive power demand is zero.

[0100] Substitute the voltage phase angle, short-circuit ratio and impedance ratio when the initial reactive power demand is zero into equation (13) to calculate the initial value of the initial reactive power demand, which is recorded as Q eq1 .

[0101] S3: Determine the voltage phase angle when the initial reactive power demand is the initial value; and determine the corrected reactive power demand based on the voltage phase angle when the initial reactive power demand is the initial value.

[0102] For a single-infeed system, the initial value of the initial reactive power demand, the short-circuit ratio, and the impedance ratio are substituted into equation (12) to calculate the voltage phase angle when the initial reactive power demand is the initial value.

[0103] Substituting the voltage phase angle, short-circuit ratio and impedance ratio when the initial reactive power demand is the initial value into formula (11), the initial reactive power demand obtained is the corrected reactive power demand, which is recorded as Q2.

[0104] For a multi-infeed system, the initial reactive power demand, the short-circuit ratio, and the impedance ratio are substituted into Equation (14) to calculate the voltage phase angle when the initial reactive power demand is the initial value.

[0105] Substituting the voltage phase angle, short-circuit ratio and impedance ratio when the initial reactive power demand is the initial value into formula (13), the initial reactive power demand obtained is the corrected reactive power demand, denoted as Q eq2 .

[0106] S4: Calculate the absolute value of the difference between the corrected reactive demand and the initial value; when the absolute value is greater than or equal to a set threshold, use the corrected reactive demand as the initial value of the reactive demand, and re-determine the voltage phase angle and the corrected reactive demand until the absolute value of the difference between the corrected reactive demand and the initial value is less than the set threshold.

[0107] For a single-feed system, calculate abs(Q2-Q1). If abs(Q2-Q1) < the set threshold δ, the correction ends. Otherwise, set Q1=Q2 and return to S3.

[0108] For a multi-infeed system, calculate abs(Q eq2 -Q eq1 ), if abs(Q eq2 -Q eq1 )<set threshold δ, then the correction ends, otherwise, let Q eq1 =Q eq2 , return to S3.

[0109] S5: Determine the reactive power demand of the new energy grid-connected system according to the corrected reactive power demand when the absolute value is less than the set threshold.

[0110] For a single renewable energy feed-in system, the corrected reactive power demand when its absolute value is less than the set threshold is the reactive power demand of the renewable energy grid-connected system.

[0111] For a renewable energy multi-feed system, the reactive power demand of the renewable energy grid-connected system is obtained by subtracting the additional reactive power ΔQ of the renewable energy from the corrected reactive power demand when the absolute value is less than the set threshold.

[0112] The additional reactive power of node i is calculated based on the self-impedance of node i, the mutual impedance between node i and node j, and the original injected complex power of node j, thereby obtaining the additional reactive power of the new energy.

[0113] Build separately as Figure 4 、 Figure 8 The three-machine, nine-node single-infeed system model and the three-machine, nine-node multi-infeed system model are shown. Renewable energy sources with different penetration rates are connected at different locations. The reactive power support capacity required to maintain a constant voltage at the access point before and after the new energy is connected is calculated to verify the method disclosed in this embodiment.

[0114] For the single-infeed system, the parameters of the new energy line line 1 are shown in Table 1, and the other line parameters are the standard parameters of the IEEE 9-bus model.

[0115] Table 1 Line 1 parameters

[0116] Resistance R / pu Reactance X / pu 0.0151 0.3987

[0117] The simulation results are compared with the simplified calculation results proposed. Figure 5-Figure 7 The specific calculation results are shown in Table 2:

[0118] Table 2 Specific calculation results of single feed system

[0119]

[0120] According to the comparison results, the simplified calculation method for the reactive power support demand of new energy to maintain the voltage level of the new energy grid connection point proposed in this disclosure calculates the reactive power demand with a maximum error of less than 5% compared with the simulation result. The calculation accuracy meets the engineering requirements, and it has the advantages of fast calculation speed and low information requirement. It simplifies the analysis and calculation of the reactive support demand of new energy access to the power grid to a certain extent, and can guide the configuration of reactive compensation capacity in new energy sites to a certain extent.

[0121] For a multi-infeed system, three renewable energy stations are connected at node 8. The reactive power support capacity required to maintain a constant voltage at station 1 before and after the renewable energy connection is implemented is calculated. The renewable energy line parameters are shown in Table 3. Other line parameters follow the IEEE 9-bus model standard.

[0122] Table 3 Line parameters

[0123] Resistance R / pu Reactance X / pu line1 0.0302 0.7387 line2 0.0378 0.9087 line3 0.0378 0.9087

[0124] The simulation results are compared with the simplified calculation results proposed. Figure 9 shown.

[0125] According to the comparison results, the simplified calculation method for the reactive power support demand of new energy to maintain the voltage level of the new energy grid connection point proposed in this disclosure calculates the reactive power demand with a maximum error of less than 4% compared with the simulation result. The calculation accuracy meets the engineering requirements, and it has the advantages of fast calculation speed and low information requirement. It simplifies the analysis and calculation of the reactive support demand of new energy access to the power grid to a certain extent, and can guide the configuration of reactive compensation capacity in new energy sites to a certain extent.

[0126] Therefore, the method disclosed in this embodiment realizes the accurate calculation of the reactive power demand of the system by continuously calculating the voltage phase angle and reactive power demand. Moreover, based only on the short-circuit ratio information and impedance ratio information at the grid connection point, the reactive power demand of new energy can be calculated more accurately, thereby guiding the configuration of reactive power compensation capacity in the new energy station and simplifying the calculation method.

[0127] Example 2

[0128] In this embodiment, a new energy reactive power demand determination system for maintaining a grid connection point voltage level is disclosed, including:

[0129] Data acquisition module, used to obtain the short-circuit ratio and impedance ratio of the new energy grid-connected system;

[0130] The reactive power demand initial value acquisition module is used to calculate the voltage phase angle when the initial reactive power demand is zero based on the short-circuit ratio and the impedance ratio; and determine the initial value of the initial reactive power demand based on the voltage phase angle, the short-circuit ratio and the impedance ratio when the initial reactive power demand is zero;

[0131] The modified reactive power demand acquisition module is used to determine the voltage phase angle when the initial reactive power demand is the initial value; and determine the modified reactive power demand according to the voltage phase angle when the initial reactive power demand is the initial value;

[0132] The reactive power demand correction module is used to calculate the absolute value of the difference between the corrected reactive power demand and the initial value; when the absolute value is greater than or equal to a set threshold, the corrected reactive power demand is used as the initial value of the initial reactive power demand, and the voltage phase angle and the corrected reactive power demand are re-determined until the absolute value of the difference between the corrected reactive power demand and the initial value is less than the set threshold;

[0133] The system reactive power demand determination module is used to determine the reactive power demand of the renewable energy grid-connected system based on the corrected reactive power demand when the absolute value is less than the set threshold.

[0134] Example 3

[0135] In this embodiment, an electronic device is disclosed, including a memory and a processor, and computer instructions stored in the memory and running on the processor. When the computer instructions are executed by the processor, the steps described in the method for determining the reactive power demand of new energy to maintain the voltage level of the grid connection point disclosed in Example 1 are completed.

[0136] Example 4

[0137] In this embodiment, a computer-readable storage medium is disclosed for storing computer instructions. When the computer instructions are executed by a processor, the steps described in the method for determining the reactive power demand of new energy for maintaining the voltage level of the grid connection point disclosed in Example 1 are completed.

[0138] 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 claims of the present invention.

Claims

1. A method for determining the reactive power demand of new energy sources to maintain the voltage level at the grid connection point, characterized in that: include: Obtain the short-circuit ratio and impedance ratio of the new energy grid-connected system; According to the short-circuit ratio and impedance ratio, the voltage phase angle when the initial reactive power demand is zero is calculated; Determine the initial value of the initial reactive power demand according to the voltage phase angle, short circuit ratio and impedance ratio when the initial reactive power demand is zero; Determine the voltage phase angle when the initial reactive power demand is the initial value; Determine the voltage phase angle based on the short-circuit ratio, impedance ratio and voltage phase angle calculation model; For renewable energy multi-feed systems, the voltage phase angle calculation model is: ； For a single-feed renewable energy system, the voltage phase angle calculation model is: ； in, is the voltage phase angle, is the initial reactive power demand of the multi-infeed system, is the equivalent active power of the multi-infeed system, SCR is the short-circuit ratio, is the impedance ratio; Determine reactive power demand based on voltage phase angle, short-circuit ratio, impedance ratio and reactive power demand calculation model; For renewable energy multi-feed systems, the reactive power demand calculation model is: ； For a renewable energy single-feed system, the reactive power demand calculation model is: ； Among them, SCR is the short circuit ratio, is the impedance ratio, is the initial reactive power demand of the multi-infeed system, is the initial reactive power demand of the single-infeed system, is the voltage phase angle of the new energy access point; Determine the corrected reactive power demand based on the voltage phase angle when the initial reactive power demand is the initial value; Calculate the absolute value of the difference between the corrected reactive power demand and the initial value; When the absolute value is greater than or equal to the set threshold, the corrected reactive power demand is used as the initial value of the initial reactive power demand, and the voltage phase angle and the corrected reactive power demand are re-determined until the absolute value of the difference between the corrected reactive power demand and the initial value is less than the set threshold; The reactive power demand of the new energy grid-connected system is determined according to the corrected reactive power demand when the absolute value is less than the set threshold.

2. The method for determining the reactive power demand of new energy sources for maintaining the voltage level at the grid connection point according to claim 1, characterized in that: For a single renewable energy feed-in system, the corrected reactive power demand when its absolute value is less than the set threshold is the reactive power demand of the renewable energy grid-connected system.

3. The method for determining the reactive power demand of new energy sources for maintaining the voltage level at the grid connection point according to claim 1, characterized in that: For renewable energy multi-feed systems, according to the node i Self-impedance, node i With node j Mutual impedance and nodes j The original injected complex power is calculated to obtain the node i Additional active power and nodes i Additional reactive power; According to the node i Additional active power, node i The additional reactive power of the node is calculated i The additional complex power of According to the node i Additional complex power and nodes i The original injected complex power is calculated to obtain the node i Equivalent grid-connected capacity; node i The short-circuit capacity and node i The ratio of equivalent grid-connected capacity is the node i short-circuit ratio.

4. The method for determining the reactive power demand of new energy sources for maintaining the voltage level at the grid connection point according to claim 3, wherein: For renewable energy multi-feed systems, the reactive power demand of renewable energy grid-connected systems is obtained by subtracting the additional reactive power of renewable energy from the corrected reactive power demand when the absolute value is less than the set threshold.

5. The method for determining the reactive power demand of new energy sources for maintaining the voltage level at the grid connection point according to claim 1, characterized in that: The equivalent active power of the multi-infeed system is the sum of the active power generated by the renewable energy and the additional active power.

6. A new energy reactive power demand determination system for maintaining the voltage level at the grid connection point, characterized in that: include: Data acquisition module, used to obtain the short-circuit ratio and impedance ratio of the new energy grid-connected system; The reactive power demand initial value acquisition module is used to calculate the voltage phase angle when the initial reactive power demand is zero based on the short-circuit ratio and the impedance ratio; Determine the initial value of the initial reactive power demand according to the voltage phase angle, short circuit ratio and impedance ratio when the initial reactive power demand is zero; Determine the voltage phase angle based on the short-circuit ratio, impedance ratio and voltage phase angle calculation model; For renewable energy multi-feed systems, the voltage phase angle calculation model is: ； For a single-feed renewable energy system, the voltage phase angle calculation model is: ； in, is the voltage phase angle, is the initial reactive power demand of the multi-infeed system, is the equivalent active power of the multi-infeed system, SCR is the short-circuit ratio, is the impedance ratio; Determine reactive power demand based on voltage phase angle, short-circuit ratio, impedance ratio and reactive power demand calculation model; For renewable energy multi-feed systems, the reactive power demand calculation model is: ； For a renewable energy single-feed system, the reactive power demand calculation model is: ； Among them, SCR is the short circuit ratio, is the impedance ratio, is the initial reactive power demand of the multi-infeed system, is the initial reactive power demand of the single-infeed system, is the voltage phase angle of the new energy access point; The modified reactive power demand acquisition module is used to determine the voltage phase angle when the initial reactive power demand is the initial value; and determine the modified reactive power demand according to the voltage phase angle when the initial reactive power demand is the initial value; The reactive power demand correction module is used to calculate the absolute value of the difference between the corrected reactive power demand and the initial value; when the absolute value is greater than or equal to a set threshold, the corrected reactive power demand is used as the initial value of the initial reactive power demand, and the voltage phase angle and the corrected reactive power demand are re-determined until the absolute value of the difference between the corrected reactive power demand and the initial value is less than the set threshold; The system reactive power demand determination module is used to determine the reactive power demand of the renewable energy grid-connected system based on the corrected reactive power demand when the absolute value is less than the set threshold.

7. An electronic device, characterized in that: The invention comprises a memory and a processor, and computer instructions stored in the memory and executed on the processor. When the computer instructions are executed by the processor, the steps of the method for determining the reactive power demand of new energy for maintaining the voltage level of the grid connection point as described in any one of claims 1 to 5 are completed.

8. A computer-readable storage medium, characterized in that Used to store computer instructions, which, when executed by a processor, complete the steps of the method for determining the reactive power demand of new energy to maintain the voltage level of the grid connection point as described in any one of claims 1 to 5.

Images