A new energy reactive power safety interval calculation method and related device

Abstract

The application discloses a new energy reactive power safety interval calculation method and related device, and the method comprises the following steps: collecting centralized new energy station core operation parameters to determine voltage safety constraint boundary; based on the core operation parameters, the voltage calculation formula of the grid-connected point is corrected according to the power system flow calculation principle and the impedance characteristic of the medium-voltage line to obtain a complete voltage calculation formula; the influence law of reactive power on voltage fluctuation is qualitatively analyzed according to the voltage safety constraint boundary and the PV curve corresponding to the complete voltage calculation formula; the extreme point coordinates and the monotonicity of the PV curve are determined according to the complete voltage calculation formula and the influence law of reactive power; the reactive power safety interval is calculated based on the active power modulation range, the extreme point coordinates and the monotonicity to obtain a target safety interval. The application can solve the technical problems that the prior art ignores the system line impedance and easily leads to the voltage out-of-limit crossing control of new energy in the active power regulation process, thereby causing the risk of system control.

Description

Technical Field

[0001] This application relates to the field of power system technology, and in particular to a method and related device for calculating the reactive power safety range of new energy sources. Background Technology

[0002] With the increasing demand for addressing global climate change, new energy sources, represented by renewable energy, are being developed and utilized on a large scale. The proportion of synchronous generators in the power system continues to decline, while the proportion of power electronic equipment is rapidly increasing, and the power grid is accelerating its transformation towards a power electronic form. The growth of renewable energy scale is particularly significant in some regions. Under some typical operating scenarios, the penetration rate of renewable energy within safety constraints has reached 60%, posing new challenges to the safe and stable control of high-penetration power grids.

[0003] Traditional methods for controlling the safety and stability of renewable energy primarily employ physical tripping, achieving power regulation by disconnecting the low-voltage side collection line switch of the renewable energy power plant's main transformer or disconnecting the grid connection line. However, this method is prone to large-scale over-tripping, and the recovery time for renewable energy to reconnect to the grid is lengthy. Furthermore, it completely eliminates reactive power support for the power plant, potentially triggering secondary risks in localized high / low voltage areas. To address this, the industry has proposed a "regulation-based tripping" technical approach. This approach leverages the millisecond-level rapid power modulation capabilities of renewable energy converters, using stability control devices to issue commands to regulate the active power output of renewable energy. This avoids the drawbacks of tripping while preserving reactive power support capabilities, making it the core development direction for renewable energy stability control.

[0004] However, the "adjustment-instead-of-switching" technology still has some problems. Specifically, centralized renewable energy sources are mostly connected to the 110kV / 220kV medium-voltage grid. The line impedance ratio at this voltage level is relatively large, and conventional operation often ignores the system resistance. Furthermore, rapid active power modulation can cause generator-end voltage exceedances, triggering high-low voltage ride-throughs in renewable energy sources, leading to equipment no longer responding to grid commands. Since the generator-end voltage of renewable energy sources is determined by active power output, reactive power, and line impedance, under the premise of a fixed active power modulation range and line impedance, only when the initial reactive power is within a specific range can the voltage be guaranteed to remain within limits throughout the active power regulation process. In other words, to achieve stable control of centralized renewable energy power systems and realize "adjustment-instead-of-switching," calculating an accurate and reliable reactive power safety range is essential. Currently, either unreasonable reactive power settings lead to voltage exceedances and control failures, or excessively narrowing the reactive power range wastes the reactive power regulation capacity of the power plants. Summary of the Invention

[0005] This application provides a method and related device for calculating the reactive power safety range of new energy sources, which solves the technical problem that the existing technology ignores the system line impedance and is prone to causing the voltage of new energy sources to exceed the limit and cross-control during the active power regulation process, resulting in risks to system control.

[0006] In view of this, the first aspect of this application provides a method for calculating the reactive power safety range of new energy sources, including:

[0007] Collect core operating parameters of the transmission lines of the target centralized new energy power plants to determine voltage safety constraint boundaries;

[0008] Based on the core operating parameters, and in accordance with the power system flow calculation principle and the impedance characteristics of medium-voltage lines, the voltage calculation formula at the grid connection point is modified to take resistance into account, resulting in a complete voltage calculation formula.

[0009] Based on the voltage safety constraint boundary and the PV curve corresponding to the complete voltage calculation formula, the influence of reactive power on voltage fluctuation is qualitatively analyzed, and the reactive power influence law is obtained.

[0010] The extreme point coordinates and monotonic characteristics of the PV curve are determined based on the complete voltage calculation formula and the reactive power influence law.

[0011] The reactive power safety interval is calculated based on the active power modulation range, the coordinates of the extreme points, and the monotonic characteristics to divide the scene, and the target safety interval is obtained.

[0012] Preferably, the complete computational model is expressed as follows:

[0013]

[0014] Where U is the grid connection voltage of the new energy source, P and Q represent the active and reactive power outputs of the new energy source, respectively, and R, Z, and X represent the resistance, impedance, and reactance of the new energy transmission line, respectively.

[0015] Preferably, the qualitative analysis of the impact of reactive power on voltage fluctuations based on the voltage safety constraint boundary and the PV curve corresponding to the complete voltage calculation formula, to obtain the reactive power impact law, includes:

[0016] Under different reactive power conditions, the selected typical parameters of the medium-voltage line are substituted into the complete voltage calculation formula to calculate the grid connection point voltage under different active power output, and a cluster of PV curves is plotted.

[0017] By comparing the grid connection point voltage in the PV curve cluster with the voltage safety constraint boundary, the influence law of reactive power on voltage fluctuation is determined, and the reactive power influence law is obtained.

[0018] Preferably, determining the extreme point coordinates and monotonic characteristics of the PV curve based on the complete voltage calculation formula and the reactive power influence law includes:

[0019] Based on the aforementioned reactive power influence law, the first derivative of the grid connection point voltage with respect to active power is calculated according to the complete voltage calculation formula. The first derivative is set to 0, and the maximum active power is calculated.

[0020] Substitute the maximum active power value into the complete voltage calculation formula to calculate the maximum voltage value, determine the maximum grid connection point voltage of the extreme point of the PV curve, and generate the coordinates of the extreme point.

[0021] By taking the first derivative of the active power maximum with respect to reactive power, the influence of reactive power on the active power at the extreme point is derived, and the monotonic characteristics are obtained.

[0022] Preferably, the calculation of the reactive power safety interval based on the active power modulation range, the extreme point coordinates, and the monotonic characteristics to obtain the target safety interval includes:

[0023] If the maximum value of the active power is not lower than the maximum value of the active power modulation range, then the first reactive power safety interval is calculated based on the limit value of the active power modulation range and the monotonic characteristic.

[0024] If the maximum active power value is within the active power modulation range, then the second reactive power safety interval is calculated based on the extreme point coordinates and the monotonic characteristic.

[0025] The first reactive power safety interval and the second reactive power safety interval constitute the target safety interval.

[0026] The second aspect of this application provides a new energy reactive power safety range calculation device, comprising:

[0027] The data acquisition unit is used to collect the core operating parameters of the transmission lines of the target centralized new energy power station and determine the voltage safety constraint boundary.

[0028] The formula correction unit is used to correct the grid connection point voltage calculation formula based on the core operating parameters, the power system flow calculation principle, and the impedance characteristics of medium-voltage lines, taking resistance into account, to obtain the complete voltage calculation formula.

[0029] The impact analysis unit is used to qualitatively analyze the impact of reactive power on voltage fluctuations based on the voltage safety constraint boundary and the PV curve corresponding to the complete voltage calculation formula, and to obtain the reactive power impact law.

[0030] An extreme value calculation unit is used to determine the extreme point coordinates and monotonic characteristics of the PV curve based on the complete voltage calculation formula and the reactive power influence law.

[0031] The interval calculation unit is used to calculate the reactive power safety interval based on the active power modulation range, the coordinates of the extreme point, and the monotonic characteristics to divide the scene, and obtain the target safety interval.

[0032] Preferably, the complete computational model is expressed as follows:

[0033]

[0034] Where U is the grid connection voltage of the new energy source, P and Q represent the active and reactive power outputs of the new energy source, respectively, and R, Z, and X represent the resistance, impedance, and reactance of the new energy transmission line, respectively.

[0035] Preferably, the influence analysis unit is specifically used for:

[0036] Under different reactive power conditions, the selected typical parameters of the medium-voltage line are substituted into the complete voltage calculation formula to calculate the grid connection point voltage under different active power output, and a cluster of PV curves is plotted.

[0037] By comparing the grid connection point voltage in the PV curve cluster with the voltage safety constraint boundary, the influence law of reactive power on voltage fluctuation is determined, and the reactive power influence law is obtained.

[0038] A third aspect of this application provides a new energy reactive power safety range calculation device, the device including a processor and a memory;

[0039] The memory is used to store program code and transmit the program code to the processor;

[0040] The processor is used to execute the new energy reactive power safety range calculation method described in the first aspect according to the instructions in the program code.

[0041] The fourth aspect of this application provides a computer-readable storage medium for storing program code for executing the new energy reactive power safety range calculation method described in the first aspect.

[0042] As can be seen from the above technical solutions, the embodiments of this application have the following advantages:

[0043] This application provides a method for calculating the reactive power safety range of new energy sources, including: collecting core operating parameters of the transmission lines of the target centralized new energy power plant to determine the voltage safety constraint boundary; based on the core operating parameters, and according to the power system flow calculation principle and the impedance characteristics of medium-voltage lines, correcting the voltage calculation formula at the grid connection point by considering resistance to obtain the complete voltage calculation formula; qualitatively analyzing the influence of reactive power on voltage fluctuations based on the voltage safety constraint boundary and the PV curve corresponding to the complete voltage calculation formula to obtain the reactive power influence law; determining the extreme point coordinates and monotonic characteristics of the PV curve according to the complete voltage calculation formula and the reactive power influence law; and calculating the reactive power safety range based on the active power modulation range, extreme point coordinates, and monotonic characteristics to obtain the target safety range.

[0044] The reactive power safety interval calculation method for new energy provided in this application corrects the grid connection point voltage calculation formula by considering resistance based on the power system flow calculation principle and the impedance characteristics of medium-voltage lines. It abandons the simplistic assumption of ignoring resistance in high-voltage grids, accurately reflecting the true voltage variation with active and reactive power. It solves the fundamental problem of being unable to accurately predict voltage changes at the terminal during active power regulation. Furthermore, by qualitatively analyzing the impact of reactive power changes on voltage fluctuations through PV curve plotting, it clarifies the causal relationship between reactive power and voltage fluctuations, accurately locating the maximum value and solving the problem of not being able to determine the most dangerous voltage conditions, providing a theoretical basis for the quantitative calculation of the reactive power interval. Moreover, the scenario-based reactive power safety interval calculation ensures accurate and reliable results, ensuring that the terminal voltage will not exceed the safety limit during emergency active power regulation across the entire range, fundamentally avoiding triggering high and low voltage ride-through control. Therefore, this application solves the technical problems of existing technologies that ignore system line impedance and easily lead to new energy voltage exceeding limits and ride-through control during active power regulation, resulting in risks to system control. Attached Figure Description

[0045] Figure 1 A flowchart illustrating a method for calculating the reactive power safety range of new energy sources, provided in an embodiment of this application;

[0046] Figure 2 This is a schematic diagram of the structure of a new energy reactive power safety range calculation device provided in an embodiment of this application;

[0047] Figure 3 A PV curve of the transmission line of a centralized new energy power plant system provided in this application embodiment, ignoring the system power grid.

[0048] Figure 4 A PV curve diagram of the transmission line of a centralized new energy power plant system provided in this application embodiment, considering the system power grid.

[0049] Figure 5 The graphs showing the monotonic variation of grid connection point voltage with active power under different reactive power conditions are provided for embodiments of this application. Detailed Implementation

[0050] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0051] For easier understanding, please refer to Figure 1 An embodiment of a method for calculating the reactive power safety range of new energy sources provided in this application includes:

[0052] Step 101: Collect the core operating parameters of the transmission lines of the target centralized new energy power station and determine the voltage safety constraint boundary.

[0053] In the process of "adjustment instead of switching" active power modulation of renewable energy sources, most centralized renewable energy plants respond to AVC control, adjusting the reactive power of renewable energy on a minute-by-minute time scale based on the 220kV grid connection voltage. Constant reactive power control is adopted within each adjustment time cycle. Rapid changes in the active power of renewable energy may cause the voltage at the renewable energy generator terminals to exceed limits, leading to voltage ride-through. During this ride-through, the renewable energy equipment no longer responds to fast power adjustment commands, resulting in the failure of safety and stability control and posing a challenge to the safe operation of the power grid. This embodiment analyzes the control parameters of centralized renewable energy power plants under this background to obtain an accurate and reliable reactive power safety range. By reasonably arranging the initial reactive power range of renewable energy, it ensures that within this range, changes in active power within its safety range will not cause voltage ride-through, thus ensuring the stability of "adjustment instead of switching" from the root cause.

[0054] Because the R / X ratios of transmission lines from different centralized renewable energy power plants vary greatly, voltage safety constraints may also differ slightly depending on grid requirements. Directly applying general parameters would result in calculated ranges that deviate significantly from the actual operating conditions of the power plants, leading to either voltage exceeding limits or wasted reactive power resources during actual operation. Therefore, the core operating parameters in this embodiment are relevant data specific to the target centralized renewable energy power plant, which can be divided into core operating data and electrical parameters. For example, the electrical parameters of renewable energy transmission lines include impedance Z, resistance R, and reactance X, all of which can be expressed as per-unit values; the renewable energy active power modulation range can be expressed as… Correspondingly, a value of 0 represents the rated active power output; the adjustable range of reactive power from new energy sources can be expressed as... Negative values ​​indicate the absorption of reactive power, while positive values ​​indicate reactive power; the safe operating limit of the power grid voltage, also known as the voltage safety constraint boundary, is expressed as: ,in, , The collected data can form a standardized parameter dataset, providing a reliable data foundation for subsequent data analysis, formula derivation, and calculation, ensuring the accuracy and reliability of the calculated intervals from the source.

[0055] Step 102: Based on the core operating parameters, and in accordance with the power system flow calculation principle and the impedance characteristics of medium-voltage lines, the voltage calculation formula at the grid connection point is modified to take resistance into account, resulting in a complete voltage calculation formula.

[0056] Furthermore, the complete voltage calculation formula is expressed as:

[0057]

[0058] Where U is the grid connection voltage of the new energy source, P and Q represent the active and reactive power outputs of the new energy source, respectively, and R, Z, and X represent the resistance, impedance, and reactance of the new energy transmission line, respectively.

[0059] The principle of power flow calculation in power systems and the impedance characteristics of medium-voltage lines are used for impedance variation analysis: Since the impedance ratio R / X of common transmission network lines is small, the impedance R can be ignored. Under such circumstances, the formula for calculating the grid connection point voltage of new energy power plants can be expressed as:

[0060]

[0061] If we assume the reactance X = 0.2, a PV curve can be plotted based on this. Please refer to [link / reference]. Figure 3 At this point, the PV curve is monotonically decreasing. However, since centralized renewable energy sources are often connected to the grid through 220kV or 110kV medium-voltage power systems, the network impedance ratio R / X is relatively high, reactive power support resources are relatively scarce, and voltage support capabilities are weak. Therefore, when the active power of renewable energy sources changes rapidly, the voltage at its connection point may fluctuate significantly. If the fluctuation amplitude exceeds the normal operating limit, it will trigger high-low voltage ride-through control switching, potentially causing oscillation risks. Therefore, in this embodiment, when the system impedance is relatively high, the grid connection point voltage is calculated considering resistance. Based on this, the original grid connection point calculation formula can be corrected and adjusted to obtain a more complete voltage calculation formula.

[0062] Step 103: Based on the voltage safety constraint boundary and the PV curve corresponding to the complete voltage calculation formula, qualitatively analyze the influence law of reactive power on voltage fluctuation and obtain the reactive power influence law.

[0063] Further, step 103 includes:

[0064] Under different reactive power conditions, the selected typical parameters of the medium-voltage line are substituted into the complete voltage calculation formula to calculate the grid connection point voltage under different active power output, and a cluster of PV curves is plotted.

[0065] By comparing the grid connection point voltage in the PV curve cluster with the voltage safety constraint boundary, the influence law of reactive power on voltage fluctuation is determined, and the reactive power influence law is obtained.

[0066] It should be noted that in the complete voltage calculation formula for new energy sources, R, Z, and X need to be selected according to the actual situation. In this embodiment, some typical values ​​will be pre-selected, i.e., typical parameters of medium-voltage lines, such as impedance Z=0.2, resistance R=0.09, and reactance X=0.18. Then, under different reactive power Q values, the complete voltage calculation formula is used to calculate the grid connection point voltage under different conditions based on these typical parameters. The PV curves under different Q values ​​are plotted with P as the abscissa and U as the ordinate. Please refer to [link / reference]. Figure 4 The values ​​of Q are -0.7, -0.1, and 0.1, respectively; and the range of the active power output P during the process is 0 to 1 p.u.

[0067] Voltage safety constraint boundary is expressed as ,Right now ;according to Figure 4 Analysis shows that, with a constant reactive power Q, the voltage at the generator terminals of the renewable energy source, i.e., the grid connection point voltage, changes smoothly with the active power output. Assuming the renewable energy source initially operates within its normal voltage range, i.e., within the voltage safety constraint boundary, when Q = 0.7, as the active power output P of the renewable energy source decreases, the grid connection point voltage may fall below its normal minimum boundary. For example, when P = 0, the grid connection point voltage drops to 0.85. At this point, the grid connection point voltage is lower than the minimum value of the voltage safety constraint boundary (0.9), causing the renewable energy inverter to enter low-voltage ride-through control. When Q = -0.1, as the active power output P of the renewable energy source increases from 0 to 1, the grid connection point voltage remains within the voltage safety constraint boundary, ensuring that the renewable energy source will not experience voltage ride-through faults and can thus respond normally to the grid's power fast-adjustment command. When Q = 0.1, during the process of reducing the active power output P of the renewable energy source, the grid connection point voltage may exceed the maximum value of the voltage safety constraint boundary (1.1), causing the renewable energy inverter to enter high-voltage ride-through control.

[0068] This is the law of the influence of reactive power Q on the grid connection point voltage U. That is, the initial reactive power range must be limited to ensure that the active power output will not cause voltage ride-through during the fast adjustment process and to ensure the stability of system control. The reactive power influence law here is a qualitative analysis, so it only analyzes the necessity of determining the reactive power range. The subsequent step is to perform quantitative calculations based on this to accurately obtain the safe range of reactive power.

[0069] Step 104: Determine the extreme point coordinates and monotonic characteristics of the PV curve based on the complete voltage calculation formula and the reactive power influence law.

[0070] Further, step 104 includes:

[0071] Based on the law of reactive power influence, the first derivative of the grid connection point voltage with respect to active power is calculated according to the complete voltage calculation formula. The first derivative is set to 0, and the maximum active power is calculated.

[0072] Substitute the maximum active power value into the complete voltage calculation formula to calculate the maximum voltage value, determine the maximum grid connection point voltage of the extreme point of the PV curve, and generate the coordinates of the extreme point.

[0073] By taking the first derivative of the active power maxima with respect to reactive power, the influence of reactive power on the active power at the extreme points is derived, and the monotonic characteristics are obtained.

[0074] It should be noted that, based on the reactive power influence law and the complete voltage calculation formula, the coordinates of the maximum point of the PV curve can be derived, which is the maximum active power and the maximum grid-connected voltage on the curve. This allows the establishment of a quantitative relationship between the voltage extreme points and active and reactive power outputs. Since the above analysis only qualitatively addresses the impact of reactive power, to quantitatively calculate the precise reactive power safety range, it is necessary to find the maximum and minimum grid-connected voltage values ​​during the active power output range modulation process under any reactive power condition. The maximum point of the PV curve is the inflection point of voltage change, determining the location of the voltage extreme points.

[0075] First, we can find the first derivative of the grid-connected voltage U with respect to the active power output P in the complete voltage calculation formula. Setting the first derivative to zero, we can then find the maximum point of the PV curve based on its characteristics, thus obtaining the formula for calculating the maximum point:

[0076]

[0077]

[0078] Based on the above formula, we can obtain... Substituting the expression for the active power output P into the above formula, we can obtain a quadratic equation for the active power output P:

[0079]

[0080] Determine the number of solutions to the above equation:

[0081]

[0082] Obviously, Since the value is greater than 0, we can determine that the above quadratic equation has two distinct positive real roots:

[0083]

[0084] Based on the characteristics of the PV curve, taking the portion where U is greater than 0, the positive real root can be written as:

[0085]

[0086] Based on the characteristics of the PV curve, the active power maximum corresponds to the voltage maximum point. Expressed as:

[0087]

[0088] Substituting this into the expression for the positive real root, we can obtain the maximum grid connection point voltage, which is the maximum grid connection point voltage corresponding to the point of maximum active power. :

[0089]

[0090] At this point, the coordinates of the extreme point are... .

[0091] Analysis of the maximum active power From the expression, we can see that if for Regarding the first derivative of Q, we can find that... It monotonically increases with Q, meaning the larger the reactive power Q, the greater the active power corresponding to the maximum voltage at the grid connection point. This is the monotonic characteristic obtained from the analysis. Specifically, based on the maximum active power... From the calculation formula, we can see that... Related to Q, i.e. It is a function of Q, Differentiate with respect to Q:

[0092]

[0093] It can be seen that, due to and ,so, It will monotonically increase as Q increases.

[0094] For actual power systems, when hour, ,Will Substitution can generally satisfy However, if we want to find the safe interval for reactive power, that is, in Under these circumstances, voltage overshoot will not occur during the process of adjusting the reduction of active power of new energy sources. This reactive power safety range is the initial reactive power operating range; this is the monotonic characteristic.

[0095] Step 105: Calculate the reactive power safety interval based on the active power modulation range, extreme point coordinates, and monotonic characteristics to obtain the target safety interval.

[0096] Further, step 105 includes:

[0097] If the maximum active power is not lower than the maximum value of the active power modulation range, then the first reactive power safety interval is calculated based on the limit value of the active power modulation range and the monotonic characteristics.

[0098] If the maximum active power is within the active power modulation range, the second reactive power safety interval is calculated based on the coordinates of the extreme point and the monotonic characteristics.

[0099] The first reactive power safety interval and the second reactive power safety interval constitute the target safety interval.

[0100] It should be noted that this embodiment is based on the coordinates of the extreme points. Maximum active power in With active power modulation range Comparative analysis reveals that the interval solution process can be divided into two scenarios, namely... and There are two scenarios; then, different interval calculation schemes are designed according to different scenarios to obtain a reactive power safety interval that is more in line with the actual working conditions.

[0101] Please see Figure 5 The PV curve, in In this case, The PV curve within the range is monotonically increasing, that is, when... At this time, the grid connection point voltage is at its highest, and its value is taken as 1.1 pu. Calculate the corresponding reactive power Q at this time, which is the upper limit of reactive power generated by the new energy source; when At this time, the grid connection point voltage is at its lowest, and the value is taken as 0.9pu. Calculate the corresponding reactive power Q at this time, which is the lower limit of reactive power generated by new energy.

[0102] exist At that time, the PV curve of new energy was Within the range, it first monotonically increases, and then monotonically decreases; that is, when At this time, the grid connection point voltage is the highest, taken as 1.1 pu. Calculate the corresponding reactive power Q at this time, which is the upper limit of reactive power generated by the new energy source; when Alternatively, when the grid connection point voltage is at its lowest, it is taken as 0.9pu. Calculate the corresponding reactive power Q at this time, and then select the larger of the two values ​​as the lower limit of reactive power generated by new energy sources.

[0103] For specific calculation examples, you can ,as well as Substituting the values ​​into the complete voltage calculation formula, we obtain:

[0104]

[0105]

[0106] in, This represents the reactive power generated by the new energy power plant. Based on this formula, the lower limit of the target safe range can be calculated. This includes two lower bound values ​​for two different scenarios.

[0107] Similarly, it can be ,as well as Substituting the values ​​into the complete voltage calculation formula, we obtain:

[0108]

[0109]

[0110] The upper limit of the target safety zone can be calculated based on the formula. These are also the two upper limits under the two scenarios.

[0111] Based on the above calculation method, the first reactive power safety interval and the second reactive power safety interval can be solved respectively, and then the target safety interval can be formed.

[0112] It can be observed that when a grid fault occurs, adjusting the active power output of renewable energy sources may cause the voltage at the renewable energy generator terminals to exceed limits. During the recovery period, the renewable energy sources no longer respond to the power adjustment command, posing a risk of failure in safety and stability control. In order to achieve "adjustment instead of switching" in renewable energy stabilization measures, this embodiment proposes to discuss and calculate reasonable initial reactive power ranges under different renewable energy parameter ranges based on the renewable energy grid connection point voltage formula and corresponding PV curves in medium-voltage power systems. This prevents the problem of renewable energy generator terminal voltage exceeding limits caused by rapid active power modulation of renewable energy sources, thereby ensuring the reliability of system safety and stability control.

[0113] The reactive power safety interval calculation method for new energy provided in this application corrects the grid connection point voltage calculation formula by considering resistance based on the power system flow calculation principle and the impedance characteristics of medium-voltage lines. It abandons the simplistic assumption of ignoring resistance in high-voltage grids, accurately reflecting the true voltage variation with active and reactive power. It solves the fundamental problem of being unable to accurately predict voltage changes at the terminal during active power regulation. Furthermore, by qualitatively analyzing the impact of reactive power changes on voltage fluctuations through PV curve plotting, it clarifies the causal relationship between reactive power and voltage fluctuations, accurately locating the maximum value and solving the problem of not being able to determine the most dangerous voltage conditions, providing a theoretical basis for the quantitative calculation of the reactive power interval. Moreover, the scenario-based reactive power safety interval calculation ensures accurate and reliable results, ensuring that the terminal voltage will not exceed safety limits during emergency active power regulation across the entire range, fundamentally avoiding triggering high and low voltage ride-through control. Therefore, this application can solve the technical problems of existing technologies that ignore system line impedance and easily lead to new energy voltage exceeding limits and ride-through control during active power regulation, resulting in risks to system control.

[0114] For easier understanding, please refer to Figure 2This application provides an embodiment of a new energy reactive power safety range calculation device, including:

[0115] Data acquisition unit 201 is used to collect the core operating parameters of the transmission lines of the target centralized new energy power station and determine the voltage safety constraint boundary;

[0116] Formula correction unit 202 is used to correct the grid connection point voltage calculation formula based on core operating parameters, the power system flow calculation principle and the impedance characteristics of medium voltage lines, taking resistance into account, to obtain a complete voltage calculation formula.

[0117] The impact analysis unit 203 is used to qualitatively analyze the impact of reactive power on voltage fluctuations based on the voltage safety constraint boundary and the PV curve corresponding to the complete voltage calculation formula, and to obtain the reactive power impact law.

[0118] The extreme value calculation unit 204 is used to determine the extreme point coordinates and monotonic characteristics of the PV curve based on the complete voltage calculation formula and the reactive power influence law.

[0119] The interval calculation unit 205 is used to calculate the reactive power safety interval based on the active power modulation range, extreme point coordinates and monotonic characteristics to divide the scene, and obtain the target safety interval.

[0120] Furthermore, the complete computational model is expressed as follows:

[0121]

[0122] Where U is the grid connection voltage of the new energy source, P and Q represent the active and reactive power outputs of the new energy source, respectively, and R, Z, and X represent the resistance, impedance, and reactance of the new energy transmission line, respectively.

[0123] Furthermore, the influence analysis unit 203 is specifically used for:

[0124] Under different reactive power conditions, the selected typical parameters of the medium-voltage line are substituted into the complete voltage calculation formula to calculate the grid connection point voltage under different active power output, and a cluster of PV curves is plotted.

[0125] By comparing the grid connection point voltage in the PV curve cluster with the voltage safety constraint boundary, the influence law of reactive power on voltage fluctuation is determined, and the reactive power influence law is obtained.

[0126] This application also provides a new energy reactive power safety range calculation device, the device including a processor and a memory;

[0127] The memory is used to store program code and transfer the program code to the processor;

[0128] The processor is used to execute the new energy reactive power safety range calculation method of the above method embodiment according to the instructions in the program code.

[0129] This application also provides a computer-readable storage medium for storing program code for executing the new energy reactive power safety range calculation method of the above method embodiments.

[0130] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0131] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0132] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0133] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for executing all or part of the steps of the methods described in the various embodiments of this application through a computer device (which may be a personal computer, server, or network device, etc.). The aforementioned storage medium includes: USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, optical disks, and other media capable of storing program code.

[0134] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for calculating the reactive power safety range of new energy sources, characterized in that, include: Collect core operating parameters of the transmission lines of the target centralized new energy power plants to determine voltage safety constraint boundaries; Based on the core operating parameters, and in accordance with the power system flow calculation principle and the impedance characteristics of medium-voltage lines, the voltage calculation formula at the grid connection point is modified to take resistance into account, resulting in a complete voltage calculation formula. Based on the voltage safety constraint boundary and the PV curve corresponding to the complete voltage calculation formula, the influence of reactive power on voltage fluctuation is qualitatively analyzed, and the reactive power influence law is obtained. The extreme point coordinates and monotonic characteristics of the PV curve are determined based on the complete voltage calculation formula and the reactive power influence law. The reactive power safety interval is calculated based on the active power modulation range, the coordinates of the extreme points, and the monotonic characteristics to divide the scene, and the target safety interval is obtained.

2. The method for calculating the reactive power safety range of new energy sources according to claim 1, characterized in that, The complete computational model is expressed as follows: Where U is the grid connection voltage of the new energy source, P and Q represent the active and reactive power outputs of the new energy source, respectively, and R, Z, and X represent the resistance, impedance, and reactance of the new energy transmission line, respectively.

3. The method for calculating the reactive power safety range of new energy sources according to claim 1, characterized in that, The qualitative analysis of the impact of reactive power on voltage fluctuations, based on the voltage safety constraint boundary and the PV curve corresponding to the complete voltage calculation formula, yields the reactive power impact law, including: Under different reactive power conditions, the selected typical parameters of the medium-voltage line are substituted into the complete voltage calculation formula to calculate the grid connection point voltage under different active power output, and a cluster of PV curves is plotted. By comparing the grid connection point voltage in the PV curve cluster with the voltage safety constraint boundary, the influence law of reactive power on voltage fluctuation is determined, and the reactive power influence law is obtained.

4. The method for calculating the reactive power safety range of new energy sources according to claim 1, characterized in that, The determination of the extreme point coordinates and monotonic characteristics of the PV curve based on the complete voltage calculation formula and the reactive power influence law includes: Based on the aforementioned reactive power influence law, the first derivative of the grid connection point voltage with respect to active power is calculated according to the complete voltage calculation formula. The first derivative is set to 0, and the maximum active power is calculated. Substitute the maximum active power value into the complete voltage calculation formula to calculate the maximum voltage value, determine the maximum grid connection point voltage of the extreme point of the PV curve, and generate the coordinates of the extreme point. By taking the first derivative of the active power maximum with respect to reactive power, the influence of reactive power on the active power at the extreme point is derived, and the monotonic characteristics are obtained.

5. The method for calculating the reactive power safety range of new energy sources according to claim 4, characterized in that, The calculation of the reactive power safety interval based on the active power modulation range, the extreme point coordinates, and the monotonic characteristics to divide the scene yields the target safety interval, including: If the maximum value of the active power is not lower than the maximum value of the active power modulation range, then the first reactive power safety interval is calculated based on the limit value of the active power modulation range and the monotonic characteristic. If the maximum active power value is within the active power modulation range, then the second reactive power safety interval is calculated based on the extreme point coordinates and the monotonic characteristic. The first reactive power safety interval and the second reactive power safety interval constitute the target safety interval.

6. A new energy reactive power safety range calculation device, characterized in that, include: The data acquisition unit is used to collect the core operating parameters of the transmission lines of the target centralized new energy power station and determine the voltage safety constraint boundary. The formula correction unit is used to correct the grid connection point voltage calculation formula based on the core operating parameters, the power system flow calculation principle, and the impedance characteristics of medium-voltage lines, taking resistance into account, to obtain the complete voltage calculation formula. The impact analysis unit is used to qualitatively analyze the impact of reactive power on voltage fluctuations based on the voltage safety constraint boundary and the PV curve corresponding to the complete voltage calculation formula, and to obtain the reactive power impact law. An extreme value calculation unit is used to determine the extreme point coordinates and monotonic characteristics of the PV curve based on the complete voltage calculation formula and the reactive power influence law. The interval calculation unit is used to calculate the reactive power safety interval based on the active power modulation range, the coordinates of the extreme point, and the monotonic characteristics to divide the scene, and obtain the target safety interval.

7. The new energy reactive power safety range calculation device according to claim 6, characterized in that, The complete computational model is expressed as follows: Where U is the grid connection voltage of the new energy source, P and Q represent the active and reactive power outputs of the new energy source, respectively, and R, Z, and X represent the resistance, impedance, and reactance of the new energy transmission line, respectively.

8. The new energy reactive power safety range calculation device according to claim 6, characterized in that, The impact analysis unit is specifically used for: Under different reactive power conditions, the selected typical parameters of the medium-voltage line are substituted into the complete voltage calculation formula to calculate the grid connection point voltage under different active power output, and a cluster of PV curves is plotted. By comparing the grid connection point voltage in the PV curve cluster with the voltage safety constraint boundary, the influence law of reactive power on voltage fluctuation is determined, and the reactive power influence law is obtained.

9. A new energy reactive power safety range calculation device, characterized in that, The device includes a processor and a memory; The memory is used to store program code and transmit the program code to the processor; The processor is used to execute the new energy reactive power safety range calculation method according to any one of claims 1-5 according to the instructions in the program code.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium is used to store program code, which is used to execute the new energy reactive power safety range calculation method according to any one of claims 1-5.

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