A new energy station voltage frequency support capability comprehensive evaluation method considering device health state

Abstract

The application discloses a kind of new energy field station voltage frequency support capability comprehensive evaluation method and device considering equipment health state.The method obtains the operation state data of each equipment in new energy field station, determines equipment health index;According to the service time of equipment, the equivalent electrical distance of equipment to grid point and the spatial attenuation coefficient corresponding to reactive power, active power and inertia support, the equipment health index is corrected, and the comprehensive correction health index is obtained for each support type;According to this, determine the available reactive power support capacity, available active power support capacity and equivalent inertia of field station, and determine the voltage, frequency and inertia support capability index respectively;Each support capability index is weighted and fused, and the comprehensive support capability evaluation result is obtained.The application can reflect the influence of equipment degradation and support effect transmission attenuation on new energy field station support capability.

Description

Technical Field

[0001] This invention relates to the field of new energy power plant operation assessment and grid support capability analysis, specifically to a comprehensive assessment method and device for the voltage and frequency support capability of new energy power plants that takes into account equipment health status. Background Technology

[0002] With the deepening of my country's "dual-carbon" strategy and the continuous acceleration of the construction of new power systems, the installed capacity of new energy power generation such as wind power and photovoltaics continues to grow. New energy is gradually transforming from a traditional supplementary energy source into the main power source of the power system, and the high proportion of new energy integration has become an important trend in the future development of the power system.

[0003] Compared to traditional synchronous generators, renewable energy power generation equipment mainly connects to the grid through power electronic converters, and its voltage support, frequency support, and inertia support capabilities primarily rely on control strategies. As the penetration rate of renewable energy continues to increase, renewable energy power plants are gradually taking on functions such as voltage regulation, frequency regulation, and system stability support, and their grid connection performance directly affects the safe and stable operation of the power system.

[0004] Key equipment in renewable energy power plants, such as wind turbines, photovoltaic inverters, static var generators (SVG), energy storage converters, and main transformers, operate under complex environmental conditions for extended periods. They are affected by factors such as high and low temperatures, rain, snow, freezing, sandstorms, and salt spray, causing their performance to gradually degrade over time. Furthermore, the long-term involvement of renewable energy equipment in tasks such as automatic generation control (AGC), automatic voltage control (AVC), primary frequency regulation, and voltage control also contributes to performance degradation and changes in their health status.

[0005] Most existing methods for assessing the support capacity of new energy power stations are based on the analysis of equipment rated parameters and assume that the equipment is in a healthy operating state. They do not consider the impact of equipment aging, performance degradation and potential faults on the grid connection capability of the power station, resulting in a discrepancy between the assessment results and the actual operating state, making it difficult to accurately reflect the actual support capacity of new energy power stations.

[0006] Furthermore, existing research on the evaluation of renewable energy power plants mainly focuses on single dimensions such as power generation capacity analysis, voltage stability analysis, or frequency response analysis, lacking a comprehensive evaluation method that simultaneously considers equipment health status, service life characteristics, and spatial distribution characteristics. For renewable energy bases, multi-power plant clusters, and high-proportion renewable energy transmission systems, existing methods are insufficient to accurately evaluate the impact of equipment degradation on the overall support capacity of the power plant.

[0007] As the scale of renewable energy power plants continues to expand, the coupling relationship between changes in equipment health status and operational risks becomes increasingly complex. A decline in equipment health status not only reduces the active power output and reactive power regulation capabilities of renewable energy power plants but may also weaken their voltage support, frequency support, and inertia support capabilities, thereby increasing system operational risks. Most existing risk assessment methods only consider meteorological or operational factors and have not yet established a correlation model between equipment health status and the grid connection performance of power plants.

[0008] Therefore, a comprehensive assessment method for the voltage and frequency support capability of new energy power stations that takes into account the health status of equipment is needed to achieve unified modeling and quantitative assessment of equipment health status, power station support capability and operational risks. Summary of the Invention

[0009] This invention addresses the problems existing in the prior art by providing a comprehensive evaluation method for the voltage and frequency support capability of new energy power stations that takes into account the health status of equipment; To achieve the above objectives, the technical solution adopted by the present invention is as follows: S1, acquire the operating status data of each device in the new energy power station, and determine the equipment health index of each device based on the operating status data.

[0010] S2, based on the service time of each device, the electrical distance between each device and the grid connection point of the new energy power station, and the spatial attenuation coefficients corresponding to reactive power support, active power support and inertia support, the device health index of each device is corrected to obtain the comprehensive corrected health index of each device for reactive power support, active power support and inertia support respectively.

[0011] S3. Based on the comprehensive corrected health index of each device for reactive power support and the reactive power support capacity of the corresponding device, determine the available reactive power support capacity of the new energy power station; based on the comprehensive corrected health index of each device for active power support and the active power support capacity of the corresponding device, determine the available active power support capacity of the new energy power station; based on the comprehensive corrected health index of each device for inertia support and the inertia of the corresponding device, determine the equivalent inertia of the new energy power station.

[0012] S4. Determine the voltage support capability index of the new energy power station based on the available reactive power support capacity, determine the frequency support capability index of the new energy power station based on the available active power support capacity, and determine the inertia support capability index of the new energy power station based on the equivalent inertia.

[0013] S5, the voltage support capability index, the frequency support capability index and the inertia support capability index are weighted and fused to obtain the comprehensive support capability evaluation result of the new energy power station.

[0014] Further, S1 includes: S11, acquire the operating status data of the wind turbine, photovoltaic inverter, static var generator (SVG), energy storage converter and main transformer in the new energy power station. The operating status data includes temperature, vibration, current, voltage, harmonic content, insulation level and number of switching operations.

[0015] S12, based on the operating status data of each device, determine the parameter health level corresponding to each status parameter, and determine the component health index of the corresponding component based on the parameter health level of the same component.

[0016] S13. Based on the component health index of each part in the same equipment, determine the equipment health index of the corresponding equipment to form a three-level health status evaluation system including parameter level, component level and equipment level.

[0017] Further, S12 and S13 include: S121, based on the change type of each state parameter, the state parameters are divided into smaller-better-better, larger-better-better, and interval-optimal parameters, and the parameter values ​​of the state parameters are normalized according to the normal boundary and alarm boundary of the corresponding state parameter to obtain the parameter health of the corresponding state parameter.

[0018] S122, the component health index of the corresponding component is obtained by weighted fusion based on the health status of each parameter corresponding to the same component and the corresponding parameter weight.

[0019] S123, the device health index of the corresponding device is obtained by weighted fusion based on the component health index of each component in the same device and the corresponding component weight.

[0020] Further, S2 includes: S21, based on the service time and corresponding aging coefficient of each device, determine the service cycle correction coefficient of each device according to the exponential decay relationship.

[0021] S22, based on the electrical distance between each device and the grid connection point of the new energy power station, and the spatial attenuation coefficients corresponding to reactive power support, active power support and inertia support, determine the spatial distribution correction coefficients for each device for reactive power support, active power support and inertia support respectively.

[0022] S23. Based on the equipment health index, service cycle correction coefficient, and spatial distribution correction coefficients for reactive power support, active power support, and inertia support of each device, determine the comprehensive corrected health index of each device for reactive power support, active power support, and inertia support.

[0023] Further, S22 includes: S221, Based on the network topology of the new energy power station, determine the equivalent electrical distance from each device to the grid connection point. For a radial network, the equivalent electrical distance is determined by the sum of the per-unit values ​​of the complex impedance moduli of each branch on the path from the corresponding device to the grid connection point. For a network containing parallel channels or a ring network, the equivalent electrical distance is determined based on the transfer impedance determined by the node impedance matrix or the sensitivity of the injected power of the device to the voltage and active power transmission at the grid connection point.

[0024] S222, determine the spatial attenuation coefficients corresponding to reactive power support, active power support and inertia support respectively, and determine the spatial distribution correction coefficient of the corresponding equipment for the support type according to the equivalent electrical distance of each device and the spatial attenuation coefficient of the corresponding support type in accordance with the exponential attenuation relationship.

[0025] S223, each of the spatial distribution correction coefficients is kept in the range of greater than 0 and less than or equal to 1, and the spatial distribution correction coefficients of different devices are not normalized to sum to 1, so as to characterize the attenuation of the support capability of the corresponding device when it is transmitted to the grid connection point through the spatial distribution correction coefficient.

[0026] Further, S3 includes: S31, the available reactive power support capacity of the new energy power station is obtained by weighted summation based on the comprehensive corrected health index of each device for reactive power support and the reactive power support capacity of the corresponding device.

[0027] S4 includes: S41. Determine the voltage support capability index of the new energy power station based on the available reactive power support capacity, the reactive power support requirements of the new energy power station, and the short-circuit ratio.

[0028] S42, determine the voltage stability margin of the new energy power station based on the current active power of the new energy power station and the maximum transmission power of the system.

[0029] Furthermore, S3 also includes: S32, the available active power support capacity of the new energy power station is obtained by weighted summation based on the comprehensive corrected health index of each device for active power support and the active power support capacity of the corresponding device.

[0030] S4 further includes: S43. Based on the available active power support capacity, the active power support requirements of the new energy power station, and the response time, determine the frequency support capability index of the new energy power station.

[0031] Furthermore, S3 also includes: S33. The equivalent inertia of the new energy power station is obtained by weighted summation of the comprehensive corrected health index of each device for inertia support and the inertia of the corresponding device.

[0032] S4 further includes: S44. Based on the equivalent inertia and reference inertia of the new energy power station, determine the inertia support capability index of the new energy power station.

[0033] Further, S5 includes: S51. Based on the importance of voltage support, frequency support, and inertia support under the target power grid operation mode, a hierarchical analysis judgment matrix is ​​constructed using a scale of 1 to 9. The maximum eigenvalue and corresponding eigenvector of the hierarchical analysis judgment matrix are calculated. When the consistency ratio is less than 0.1, the normalized eigenvector is determined as the evaluation weight corresponding to the voltage support capability index, the frequency support capability index, and the inertia support capability index, respectively. The sum of each evaluation weight is 1.

[0034] S52, the comprehensive support capability index of the new energy power station is obtained by weighted summation based on the voltage support capability index, the frequency support capability index, the inertia support capability index and their respective evaluation weights.

[0035] S53, when the comprehensive support capability index is greater than or equal to 0.9, the comprehensive support capability level of the new energy power station is determined to be strong; when the comprehensive support capability index is greater than or equal to 0.8 and less than 0.9, the comprehensive support capability level is determined to be good; when the comprehensive support capability index is greater than or equal to 0.7 and less than 0.8, the comprehensive support capability level is determined to be average; when the comprehensive support capability index is less than 0.7, the comprehensive support capability level is determined to be weak.

[0036] The present invention also provides a comprehensive evaluation device for the voltage and frequency support capability of new energy power stations that takes into account the health status of equipment, including a data acquisition module, a health status evaluation module, a health status correction module, a support capability evaluation module, and a comprehensive evaluation module.

[0037] The data acquisition module is used to acquire the operating status data of each device in the new energy power station.

[0038] The health status evaluation module is used to determine the equipment health index of each device based on the operating status data.

[0039] The health status correction module is used to correct the equipment health index of each device based on the service time of each device, the electrical distance between each device and the grid connection point of the new energy power station, and the spatial attenuation coefficients corresponding to reactive power support, active power support and inertia support, so as to obtain the comprehensive corrected health index of each device for reactive power support, active power support and inertia support respectively.

[0040] The support capability evaluation module is used to determine the available reactive power support capacity of the new energy power station based on the comprehensive corrected health index of each device for reactive power support and the reactive power support capacity of the corresponding device; to determine the available active power support capacity of the new energy power station based on the comprehensive corrected health index of each device for active power support and the active power support capacity of the corresponding device; to determine the equivalent inertia of the new energy power station based on the comprehensive corrected health index of each device for inertia support and the inertia of the corresponding device; and to determine the voltage support capability index, frequency support capability index, and inertia support capability index of the new energy power station based on the available reactive power support capacity, the available active power support capacity, and the equivalent inertia, respectively.

[0041] The comprehensive evaluation module is used to perform weighted fusion of the voltage support capability index, the frequency support capability index, and the inertia support capability index to obtain the comprehensive support capability evaluation result of the new energy power station.

[0042] Compared with the prior art, the present invention has the following beneficial effects: This invention establishes a three-level health status evaluation system including parameter level, component level and equipment level. It utilizes the operating status data of equipment such as wind turbines, photovoltaic inverters, static var generators (SVG), energy storage converters and main transformers to achieve quantitative evaluation of equipment health status, thereby reflecting the operating status of the equipment.

[0043] This invention establishes a mapping relationship between equipment health status and the support capability of new energy power stations. It uses service cycle correction coefficients and spatial distribution correction coefficients corresponding to reactive power support, active power support and inertia support to correct the equipment health index. This achieves unified correction of equipment health status, service cycle characteristics and transmission attenuation of different support effects, thereby reflecting the impact of equipment degradation degree and equipment access location on the support capability of the power station.

[0044] This invention adjusts the reactive power support capacity of equipment based on the comprehensive corrected health index of the equipment for reactive power support, and determines the voltage support capability index by combining reactive power support demand and short-circuit ratio, which can evaluate the voltage support capability of new energy power stations under different equipment health states; at the same time, it determines the voltage stability margin based on the current active power and the maximum transmission power of the system.

[0045] This invention adjusts the active power support capacity of the equipment based on the comprehensive corrected health index for active power support, and determines the frequency support capability index by combining active power support demand and response time; it also adjusts the inertia of the equipment based on the comprehensive corrected health index for inertia support, and determines the equivalent inertia and inertia support capability index of the new energy power station, thereby evaluating the frequency support capability and inertia support capability of the new energy power station.

[0046] This invention establishes a unified comprehensive support capability index for new energy power plants by weighted and integrating voltage support capability index, frequency support capability index, and inertia support capability index. This enables a comprehensive evaluation of voltage support capability, frequency support capability, and inertia support capability, providing technical support for the operation and management of new energy power plants, grid dispatching decisions, and optimized control of new energy power plant clusters. Attached Figure Description

[0047] Figure 1 This is a flowchart illustrating a comprehensive evaluation method for the voltage and frequency support capability of new energy power stations, taking into account the health status of equipment, provided in an embodiment of the present invention. Detailed Implementation

[0048] The present invention will now be further described. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention. It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application.

[0049] Example 1 This embodiment provides a comprehensive evaluation method for the voltage and frequency support capabilities of new energy power plants, taking into account equipment health status. New energy power plants mainly include equipment such as wind turbines, photovoltaic inverters, static var generators (SVG), energy storage converters, and main transformers. The comprehensive evaluation method establishes a three-level health status evaluation system, including parameter level, component level, and equipment level, to determine the equipment health index of each device. Based on the equipment's service life, spatial distribution, and spatial attenuation coefficients corresponding to reactive power support, active power support, and inertia support, the equipment health index is corrected according to support type. The voltage support capability, frequency support capability, and inertia support capability of the new energy power plant are evaluated based on the correction results. Finally, the various support capability indicators are weighted and fused to obtain the comprehensive support capability evaluation result of the new energy power plant.

[0050] The comprehensive evaluation method specifically includes the following steps.

[0051] S1, Determine equipment health index Obtain the operating status data of each device in the new energy power station, and determine the equipment health index of each device based on the operating status data.

[0052] Specifically, the system acquires operational status data for wind turbines, photovoltaic inverters, static var generators (SVG), energy storage converters, and main transformers in new energy power plants. This operational status data includes monitoring parameters such as temperature, vibration, current, voltage, harmonic content, insulation level, and number of switching operations.

[0053] For each device, the corresponding parameter health is first determined based on the parameter values ​​of each status parameter; then, the component health index of the corresponding component is determined based on the health of multiple parameters corresponding to the same component; finally, the device health index is determined based on the component health indices of multiple components in the same device, thus forming a three-level health status evaluation system including parameter level, component level and device level.

[0054] S11, Determine parameter health status Let xij be the j-th state parameter of equipment of type i. Temperature, vibration, harmonic content, and number of switching operations are parameters where a smaller value indicates greater degradation; insulation resistance or insulation level are parameters where a larger value indicates better performance; operating voltage and DC bus voltage are parameters of the interval-optimal type. The health status of each parameter is determined according to its type:

[0055] in, H ij For the status parameter health level; x j,N This represents the normal boundary for parameters that are optimally smaller. x j,A To correspond to the alarm boundary, and x j,A > x j,N ; moment This means that the calculation result will be restricted to the interval [0,1].

[0056] For parameters such as insulation level, where higher is always better, let... x j,A For low-value alarm boundaries, x j,N For normal boundaries and x j,N > x j,A Then the health parameter is:

[0057] For the optimal parameters of the voltage range, let the normal range be [ x j,L ，x j,U The low and high alarm boundaries are respectively: x j,ALand x j,AU If the health level is 1 within the interval, then the health level decreases linearly towards the corresponding alarm boundary outside the interval:

[0058] The parameter health status characterizes the degree of change of the current operating state of the corresponding status parameter relative to the normal operating state, and provides a basis for the calculation of the component health index.

[0059] S12, Determine the component health index For multiple state parameters corresponding to the same component, a weighted fusion is performed based on the health status of each state parameter and its corresponding weight to obtain the component health index of the corresponding component:

[0060] Where HIpart is the component health index; wj is the corresponding parameter weight.

[0061] By fusing the health status of multiple parameters corresponding to the same component, the operating status represented by each status parameter is summarized into the component health status.

[0062] S13, Determine equipment health index After obtaining the component health index of each component in the same device, a weighted fusion is performed based on the component health index of each component and its corresponding component weight to obtain the device health index:

[0063] Where HIeq is the equipment health index; αk is the component weight coefficient. αk≥0 and the sum of the weights of all components within the same equipment is 1.

[0064] By calculating the health status of the above parameters, component health index, and equipment health index step by step, a quantitative evaluation of the health status of each piece of equipment in the new energy power station can be achieved.

[0065] S2, Corrects the equipment health index. Equipment in renewable energy power plants will experience performance degradation due to the increasing service life during long-term operation. Furthermore, different equipment has different connection locations within the power plant, and their equivalent electrical distances to the grid connection point or main substation also vary, resulting in differences in their dynamic support for grid connection voltage and frequency.

[0066] Therefore, based on the service time of each piece of equipment, the equivalent electrical distance between each piece of equipment and the grid connection point of the new energy power station or the main substation, as well as the spatial attenuation coefficients corresponding to reactive power support, active power support and inertia support, the health index of the equipment is corrected to obtain the comprehensive corrected health index of each piece of equipment for reactive power support, active power support and inertia support respectively.

[0067] S21, performing service life adjustment Considering the performance degradation of new energy equipment as its service life increases, a service life correction factor is constructed based on the equipment's service time and corresponding aging coefficient:

[0068] in, λ The aging coefficient; t This refers to the service life of the equipment.

[0069] After obtaining the service life correction factor, the equipment health index is corrected using the service life correction factor to obtain the service life corrected equipment health index.

[0070]

[0071] in, The equipment health index is adjusted for service life. Equipment health index; This is a service life correction factor.

[0072] Therefore, by using the service life correction coefficient to characterize the impact of equipment service time on equipment health status, a quantitative description of the degree of equipment aging can be achieved.

[0073] S22, Perform spatial distribution correction Based on the access location and network topology of each device in the new energy power station, the equivalent electrical distance between each device and the grid connection point or main substation is determined. For radial networks, the sum of the per-unit values ​​of the complex impedance moduli of each branch along the path from the device access node to the grid connection point is used. When parallel channels or ring networks are included, the transfer impedance is calculated using the node impedance matrix, or the sensitivity of the injected power of the device to the grid connection point voltage and active power transmission is obtained by power flow calculation and converted into the equivalent electrical distance.

[0074] Taking a radial network as an example, the equivalent electrical distance is calculated using the following formula: in, Z i For the first i The equivalent electrical distance from the equipment to the grid connection point; P i This is the set of branches from the device to the grid connection point; R l and X l The first l The resistance and reactance of each branch; Z B This is the impedance reference value.

[0075] The smaller the equivalent electrical distance, the smaller the attenuation of the equipment support effect transmitted to the grid connection point. For reactive, active, and inertial supports, the spatial attenuation coefficient can be calibrated using disturbance tests or power flow sensitivity tests, respectively. β Q 、β P and β J .

[0076] According to the i The equivalent electrical distance and the spatial attenuation coefficient corresponding to the support type r of the equipment β r Determine the spatial distribution correction coefficient:

[0077] in, is the spatial distribution correction coefficient for the i-th device with respect to support type r, and its value range is (0,1]. β r This refers to the spatial attenuation coefficient corresponding to the support type. (Each piece of equipment...) Since no normalization is performed to sum to 1, the available support capacity of the site increases accordingly when the number of identical equipment increases.

[0078] The spatial distribution correction factor is used to characterize the attenuation of the equipment support capacity when it is transferred to the grid connection point, rather than the capacity allocation ratio between equipment.

[0079] The spatial distribution correction coefficient characterizes the impact of the equipment access location and equivalent electrical distance on the equipment's support contribution.

[0080] S23, Determine the Comprehensive Adjusted Health Index After obtaining the equipment health index, service life correction factor, and spatial distribution correction factor, the three are integrated to obtain the comprehensive corrected health index of the corresponding equipment:

[0081] in, For the first i The comprehensive corrected health index of the equipment for support type r; HI eq,i Equipment health index; λ i The aging factor of the equipment; t i Service life; This is a spatial distribution correction factor; moment This is used to ensure that the correction result is within the [0,1] interval.

[0082] The above calculations provide a unified characterization of equipment health status, service life characteristics, and spatial distribution characteristics, offering a basis for equipment status correction in evaluating the voltage support capability, frequency support capability, and inertia support capability of new energy power stations.

[0083] S3, determine the available reactive power support capacity, available active power support capacity, and equivalent inertia. The available reactive power support capacity of the new energy power station is determined based on the comprehensive corrected health index of each device for reactive power support and the reactive power support capacity of the corresponding device. The available active power support capacity of the new energy power station is determined based on the comprehensive corrected health index of each device for active power support and the active power support capacity of the corresponding device. The equivalent inertia of the new energy power station is determined based on the comprehensive corrected health index of each device for inertia support and the inertia of the corresponding device.

[0084] S31, Determine available reactive power support capacity The voltage support capability of new energy power plants mainly comes from the dynamic reactive power support capability provided by static var generators (SVG), grid-type converters, wind turbine converters, and energy storage converters.

[0085] Considering the impact of equipment health status, service life, and spatial distribution on the reactive power support capability of equipment, the available reactive power support capacity of the renewable energy power station is obtained by weighted summation based on the comprehensive corrected health index of each piece of equipment for reactive power support and the corresponding reactive power support capacity of the equipment:

[0086] in, Q i Let be the rated reactive power capacity of the i-th device; HI i (Q) The comprehensive corrected health index for reactive power support of the i-th device; Q ava N represents the available reactive power support capacity of the new energy power station; N represents the number of devices participating in the reactive power support capacity evaluation.

[0087] The rated reactive power capacity of each device is corrected by comprehensively adjusting the health index, and the corrected reactive power support capacity of each device is aggregated to obtain the available reactive power support capacity of the station after considering the influence of equipment status.

[0088] S32, Determine available active power support capacity. The frequency support capability of new energy power stations mainly comes from the primary frequency regulation capability of wind turbines, the frequency regulation capability of energy storage, and the support capability of grid-type new energy equipment.

[0089] Considering the impact of equipment health status, service life, and spatial distribution on the active power support capacity of equipment, the available active power support capacity of the renewable energy power station is obtained by weighted summation based on the comprehensive corrected health index of each piece of equipment for active power support and the corresponding active power support capacity of the equipment:

[0090] in, P i Let be the rated frequency regulation capacity of the i-th device; HI i (P) is the comprehensive corrected health index of the i-th device for active power support; N is the number of devices participating in the frequency support capability evaluation.

[0091] The rated frequency regulation capacity of each device is corrected by comprehensively adjusting the health index, and the corrected frequency regulation capacity of each device is aggregated to obtain the available active power support capacity of the site after considering the influence of equipment status.

[0092] S33, Determine the equivalent inertia of new energy power stations The inertia support capability of a renewable energy power station originates from the inertia support provided by grid-connected renewable energy equipment. The equivalent inertia of the renewable energy power station is obtained by weighted summation of the comprehensive corrected health index of each device for inertia support and the inertia of the corresponding device:

[0093] in, J i Let be the rated inertia parameter of the i-th device; HI i (J) denoted as the comprehensive corrected health index for inertia support of the i-th device; N represents the number of devices participating in the inertia support capability evaluation.

[0094] S4, determine the voltage support capability index, frequency support capability index, and inertia support capability index. After obtaining the available reactive power support capacity, available active power support capacity, and equivalent inertia of the new energy power station, the voltage support capability index, frequency support capability index, and inertia support capability index of the new energy power station are determined respectively.

[0095] S41, Determine voltage support capability indicators Considering the impact of grid strength in the area where the renewable energy power station is located on voltage support capability, the short-circuit ratio at the grid connection point of the renewable energy power station is introduced. The voltage support capability index is determined based on the available reactive power support capacity, reactive power support demand, and short-circuit ratio at the grid connection point of the renewable energy power station:

[0096] VSI is the voltage support capability indicator. Q ava The available reactive power support capacity for new energy power plants; Q req For the reactive power demand capacity of new energy power plants; SCR The short-circuit ratio at the grid connection point of new energy power plants; SCR ref The reference short-circuit ratio required to meet the target operating mode.

[0097] By incorporating the impact of the comprehensive corrected health index of equipment on reactive power support capacity and the impact of the short-circuit ratio at the grid connection point on voltage support capability into the voltage support capability index, the voltage support capability of new energy power stations can be evaluated.

[0098] S42, Determine the voltage stability margin Based on the current active power of the renewable energy power station and the maximum transmission power of the system, determine the static voltage stability margin of the renewable energy power station:

[0099] in, VSM This is the static voltage stability margin; P max This represents the system's maximum transmission power. P This represents the current operating power.

[0100] The larger the static voltage stability margin, the further the system's current operating state is from the voltage instability boundary.

[0101] S43, Determine frequency support capability indicators Based on the available active power support capacity of the renewable energy power plants, the system frequency regulation demand capacity, and the frequency response time of the renewable energy power plants, the frequency support capability indicators of the renewable energy power plants are determined as follows:

[0102] Among them, FSI is the frequency support capability indicator; P ava The available active power support capacity for new energy power plants; P req This is to meet the system's frequency regulation capacity requirements; T r This refers to the frequency response time of new energy power plants. T ref This is the reference response time specified for scheduling or grid connection requirements. T ref / T r Make the response speed term dimensionless, and ensure that the shorter the response time, the larger the FSI.

[0103] The frequency regulation capacity of a new energy power station is characterized by the relationship between the available active power support capacity of the power station and the system frequency regulation demand capacity, and the frequency response capability of the new energy power station is evaluated by combining the frequency response time of the new energy power station.

[0104] S44, Determine the inertia support capacity index Based on the equivalent inertia and reference inertia values ​​of the new energy power stations, the inertia support capacity indicators of the new energy power stations are determined:

[0105] in, their Inertia support capability index; J eq The equivalent inertia of the new energy power station; J ref This is the reference inertia.

[0106] The relationship between the equivalent inertia and the reference inertia value of a new energy power station is used to characterize the inertia support capability of the new energy power station.

[0107] S5, Determine the comprehensive support capability evaluation results Taking into account the voltage support capability, frequency support capability, and inertia support capability of new energy power stations, the analytic hierarchy process (AHP) is used to determine the evaluation weights for each of the voltage support capability, frequency support capability, and inertia support capability indicators. The weighted fusion of these indicators yields a comprehensive support capability index for new energy power stations.

[0108] in, CIS As a comprehensive support capability indicator; VSI , ISF and their These are indicators of voltage, frequency, and inertia support capabilities, respectively. 、 and To correspond to the evaluation weights, all are non-negative numbers and the sum of the three is 1. In formula (16)... ISF Consistent with formula (13), both include a dimensionless response time correction term. T ref / T r .

[0109] The evaluation weights were determined using the analytic hierarchy process (AHP). Based on the importance of voltage, frequency, and inertia support under the target power grid operating mode, a third-order judgment matrix A was constructed using a scale of 1 to 9. The largest eigenvalue and corresponding eigenvector of A were obtained and normalized to obtain... , and ; Calculate the consistency ratio -R ,when -R If the value is less than 0.1, the judgment matrix is ​​accepted; otherwise, the judgment matrix is ​​adjusted and recalculated.

[0110] Based on the evaluation results of the comprehensive support capability indicators of new energy power stations, the comprehensive support capability of new energy power stations is classified into levels.

[0111] When the comprehensive support capability index of a new energy power station is greater than or equal to 0.9, the comprehensive support capability level of the new energy power station is determined to be strong.

[0112] When the comprehensive support capability index of a new energy power station is greater than or equal to 0.8 and less than 0.9, the comprehensive support capability level of the new energy power station is determined to be good.

[0113] When the comprehensive support capability index of a new energy power station is greater than or equal to 0.7 and less than 0.8, the comprehensive support capability level of the new energy power station is determined to be general.

[0114] When the comprehensive support capability index of a new energy power station is less than 0.7, the comprehensive support capability level of the new energy power station is determined to be weak.

[0115] Therefore, by evaluating the health status of equipment, correcting service cycles, correcting spatial distribution by support type, and evaluating the support capabilities of voltage, frequency, and inertia, the comprehensive support capability evaluation results of new energy power stations are obtained.

[0116] Example 2 This embodiment takes a new energy power station containing one SVG, one wind turbine, and one energy storage converter as an example. Taking the energy storage converter power module as an example, the module temperature is 45℃, the insulation resistance is 600MΩ, and the total harmonic distortion rate of the current is 3%. The normal range of the module temperature is 20℃ to 50℃, and the alarm boundary is 5℃ and 70℃. According to the formula, the health level is 1.000. The alarm boundary of the insulation resistance is 200MΩ, and the normal boundary is 800MΩ. According to the formula, the health level is 0.667. The normal boundary of the total harmonic distortion rate is 2%, and the alarm boundary is 5%. According to the formula (1), the health level is 0.667.

[0117] The weights of the three parameters of the power module in the energy storage converter are 0.4, 0.3, and 0.3 respectively, so the health index of the power module is 0.800; the health index of the control component is 0.950, and the weights of the power module and the control component are 0.6 and 0.4 respectively, thus obtaining the overall health index of the energy storage converter equipment. H Ieq =0.6×0.800+0.4×0.950=0.860. Using the same method, the equipment health indices for SVG and wind turbine units were obtained as 0.900 and 0.850, respectively.

[0118] The service lives of SVG, wind turbine generators, and energy storage converters are 5 years, 6 years, and 3 years, respectively, with aging factors of 0.010, 0.012, and 0.008, and service life correction factors of 0.951, 0.931, and 0.976, respectively. The equivalent electrical distances for the three types of equipment are 0.10, 0.18, and 0.08, respectively, using the space attenuation factor. β r =0.8, and the spatial distribution correction coefficients are 0.923, 0.866 and 0.938, respectively. The comprehensive corrected health indices obtained from formula (8) are 0.790, 0.685 and 0.788, respectively.

[0119] The rated reactive power support capacities of the three types of equipment are 20 Mvar, 15 Mvar, and 10 Mvar, respectively; the rated active power support capacities of the wind turbine and the energy storage converter are 12 MW and 20 MW, respectively; and their rated inertia parameters are 3 and 5, respectively. These are obtained from formulas (9), (12), and (14). Q ava =33.954Mvar P ava =23.970MW J eq =5.992. Because the spatial distribution correction factor is not normalized to sum to 1, when an identical device is added, its capacity after health and spatial attenuation correction will still be added to the total available capacity of the site.

[0120] set up Q req =40Mvar SCR =2.7、 SCR ref =3.0、 P req =30MW T r =1.2s、 T ref =1.0s、 J ref =8, then VSI =0.764、 ISF =0.666、 their =0.749. The judgment matrix is ​​obtained after passing the consistency check. w V =0.40、 w F =0.35、 w I =0.25, therefore CIS =0.40×0.764+0.35×0.666+0.25×0.749=0.726, the overall support capability level is general.

[0121] In online applications, steady-state operating data is updated every 60 seconds; recalculation is triggered immediately upon occurrence of voltage or frequency over-limit errors, equipment alarms, or control mode switching. CIS If the index is below 0.7 for three consecutive update cycles, a warning of weak overall support capability is triggered; if CIS If the overall corrected health index of any critical device falls below 0.6, a high-priority warning will be immediately triggered, and an alert will be issued. VSI , ISF and their The weakest equipment contributing the most damage and its corresponding status parameters. Warning cancellation uses a hysteresis of 0.03 and requires recovery over three consecutive update cycles.

[0122] Example 3 This embodiment also provides a comprehensive evaluation device for the voltage and frequency support capability of new energy power stations that takes into account the health status of equipment, including a data acquisition module, a health status evaluation module, a health status correction module, a support capability evaluation module, and a comprehensive evaluation module.

[0123] The data acquisition module is used to acquire operating status data of equipment such as wind turbines, photovoltaic inverters, static var generators (SVG), energy storage converters, and main transformers in new energy power plants. The operating status data includes temperature, vibration, current, voltage, harmonic content, insulation level, and number of switching operations.

[0124] The health status evaluation module is used to determine the health of parameters based on the parameter values ​​of each status parameter. It performs weighted fusion based on the health of each parameter corresponding to the same component and the parameter weight to obtain the component health index. It also performs weighted fusion based on the component health index and component weight of each component in the same device to obtain the device health index.

[0125] The health status correction module is used to determine the service cycle correction coefficient based on the service time and corresponding aging coefficient of each device. Based on the equivalent electrical distance between each device and the grid connection point or main substation of the new energy power plant, as well as the spatial attenuation coefficients corresponding to reactive power support, active power support, and inertia support, it determines the spatial distribution correction coefficients for each device for reactive power support, active power support, and inertia support. Based on the device health index, service cycle correction coefficient, and spatial distribution correction coefficients, it determines the comprehensive corrected health index for each device for reactive power support, active power support, and inertia support.

[0126] The support capability evaluation module is used to determine the available reactive power support capacity of the new energy power station based on the comprehensive corrected health index of each device for reactive power support and the reactive power support capacity of the corresponding device; to determine the available active power support capacity of the new energy power station based on the comprehensive corrected health index of each device for active power support and the active power support capacity of the corresponding device; and to determine the equivalent inertia of the new energy power station based on the comprehensive corrected health index of each device for inertia support and the inertia of the corresponding device. It also determines the voltage support capability index based on the available reactive power support capacity, reactive power support demand, and short-circuit ratio at the grid connection point; the static voltage stability margin based on the current active power and the system's maximum transmission power; the frequency support capability index based on the available active power support capacity, the system's frequency regulation demand capacity, and the frequency response time; and the inertia support capability index based on the equivalent inertia and the reference inertia value.

[0127] The comprehensive evaluation module is used to determine the evaluation weights corresponding to the voltage support capability index, frequency support capability index, and inertia support capability index using the analytic hierarchy process. It then performs weighted fusion of each support capability index and its corresponding evaluation weight to obtain the comprehensive support capability index of the new energy power station, and determines the comprehensive support capability level of the new energy power station based on the comprehensive support capability index.

[0128] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A comprehensive evaluation method for the voltage and frequency support capability of new energy power stations, taking into account equipment health status, characterized in that, include: S1, acquire the operating status data of each piece of equipment in the new energy power station, and determine the equipment health index of each piece of equipment based on the operating status data; S2, based on the service time of each device, the electrical distance between each device and the grid connection point of the new energy power station, and the spatial attenuation coefficients corresponding to reactive power support, active power support and inertia support, the device health index of each device is corrected to obtain the comprehensive corrected health index of each device for reactive power support, active power support and inertia support respectively. S3. Based on the comprehensive corrected health index of each device for reactive power support and the reactive power support capacity of the corresponding device, determine the available reactive power support capacity of the new energy power station. The available active power support capacity of the new energy power station is determined based on the comprehensive corrected health index of each device for active power support and the active power support capacity of the corresponding device. The equivalent inertia of the new energy power station is determined based on the comprehensive corrected health index of each device for inertia support and the inertia of the corresponding device. S4. Determine the voltage support capability index of the new energy power station based on the available reactive power support capacity, determine the frequency support capability index of the new energy power station based on the available active power support capacity, and determine the inertia support capability index of the new energy power station based on the equivalent inertia. S5, the voltage support capability index, the frequency support capability index and the inertia support capability index are weighted and fused to obtain the comprehensive support capability evaluation result of the new energy power station.

2. The comprehensive evaluation method for the voltage and frequency support capability of new energy power stations, taking into account equipment health status, as described in claim 1, is characterized in that... S1 includes: S11, acquire the operating status data of the wind turbine, photovoltaic inverter, static var generator, energy storage converter and main transformer in the new energy power station. The operating status data includes temperature, vibration, current, voltage, harmonic content, insulation level and number of switching operations. S12, based on the operating status data of each device, determine the parameter health level corresponding to each status parameter, and determine the component health index of the corresponding component based on the parameter health level of the same component; S13. Based on the component health index of each part in the same equipment, determine the equipment health index of the corresponding equipment to form a three-level health status evaluation system including parameter level, component level and equipment level.

3. The comprehensive evaluation method for the voltage and frequency support capability of new energy power stations, taking into account equipment health status, as described in claim 2, is characterized in that... S12 and S13 include: S121, based on the change type of each state parameter, each state parameter is divided into smaller-better-better, larger-better-better, and interval-optimal-better parameters, and the parameter values ​​of the state parameters are normalized according to the normal boundary and alarm boundary of the corresponding state parameter to obtain the parameter health of the corresponding state parameter. S122, perform weighted fusion based on the health status of each parameter corresponding to the same component and the corresponding parameter weight to obtain the component health index of the corresponding component; S123, the device health index of the corresponding device is obtained by weighted fusion based on the component health index of each component in the same device and the corresponding component weight.

4. The comprehensive evaluation method for the voltage and frequency support capability of new energy power stations, taking into account equipment health status, as described in claim 1, is characterized in that... S2 includes: S21, based on the service time and corresponding aging coefficient of each device, determine the service cycle correction coefficient of each device according to the exponential decay relationship; S22, based on the electrical distance between each of the devices and the grid connection point of the new energy power station, and the spatial attenuation coefficients corresponding to reactive power support, active power support and inertia support, determine the spatial distribution correction coefficients of each of the devices for reactive power support, active power support and inertia support respectively. S23. Based on the equipment health index, service cycle correction coefficient, and spatial distribution correction coefficients for reactive power support, active power support, and inertia support of each device, determine the comprehensive corrected health index of each device for reactive power support, active power support, and inertia support.

5. The comprehensive evaluation method for the voltage and frequency support capability of new energy power stations, taking into account equipment health status, as described in claim 4, is characterized in that... S22 includes: S221, based on the network topology of the new energy power station, determine the equivalent electrical distance from each device to the grid connection point. For a radial network, the equivalent electrical distance is determined by the sum of the per-unit values ​​of the complex impedance moduli of each branch on the path from the corresponding device to the grid connection point. For a network containing parallel channels or a ring network, the equivalent electrical distance is determined based on the transfer impedance determined by the node impedance matrix or the sensitivity of the injected power of the device to the voltage and active power transmission at the grid connection point. S222, determine the spatial attenuation coefficients corresponding to reactive power support, active power support and inertia support respectively, and determine the spatial distribution correction coefficient of the corresponding equipment for the support type according to the exponential attenuation relationship based on the equivalent electrical distance of each equipment and the spatial attenuation coefficient of the corresponding support type. S223, each of the spatial distribution correction coefficients is kept in the range of greater than 0 and less than or equal to 1, and the spatial distribution correction coefficients of different devices are not normalized to sum to 1, so as to characterize the attenuation of the support capability of the corresponding device when it is transmitted to the grid connection point through the spatial distribution correction coefficient.

6. The comprehensive evaluation method for the voltage and frequency support capability of new energy power stations, taking into account equipment health status, as described in claim 1, is characterized in that... S3 includes: S31, the available reactive power support capacity of the new energy power station is obtained by weighted summation based on the comprehensive corrected health index of each device for reactive power support and the reactive power support capacity of the corresponding device. S4 includes: S41. Determine the voltage support capability index of the new energy power station based on the available reactive power support capacity, the reactive power support requirements of the new energy power station, and the short-circuit ratio. S42, determine the voltage stability margin of the new energy power station based on the current active power of the new energy power station and the maximum transmission power of the system.

7. The comprehensive evaluation method for the voltage and frequency support capability of new energy power stations taking into account equipment health status as described in claim 1, characterized in that, S3 further includes: S32, the available active power support capacity of the new energy power station is obtained by weighted summation based on the comprehensive corrected health index of each device for active power support and the active power support capacity of the corresponding device. S4 further includes: S43. Based on the available active power support capacity, the active power support requirements of the new energy power station, and the response time, determine the frequency support capability index of the new energy power station.

8. The comprehensive evaluation method for the voltage and frequency support capability of new energy power stations, taking into account equipment health status, as described in claim 1, is characterized in that... S3 further includes: S33, the equivalent inertia of the new energy power station is obtained by weighted summation of the comprehensive corrected health index of each device for inertia support and the inertia of the corresponding device. S4 further includes: S44. Based on the equivalent inertia and reference inertia of the new energy power station, determine the inertia support capability index of the new energy power station.

9. The comprehensive evaluation method for the voltage and frequency support capability of new energy power stations, taking into account equipment health status, as described in claim 1, is characterized in that... S5 includes: S51, based on the importance of voltage support, frequency support and inertia support under the target power grid operation mode, construct a hierarchical analysis judgment matrix using a scale of 1 to 9, calculate the maximum eigenvalue and corresponding eigenvector of the hierarchical analysis judgment matrix, and when the consistency ratio is less than 0.1, determine the normalized eigenvector as the evaluation weight corresponding to the voltage support capability index, the frequency support capability index and the inertia support capability index respectively, wherein the sum of each evaluation weight is 1; S52, the comprehensive support capability index of the new energy power station is obtained by weighted summation based on the voltage support capability index, the frequency support capability index, the inertia support capability index and their respective evaluation weights. S53, when the comprehensive support capability index is greater than or equal to 0.9, the comprehensive support capability level of the new energy power station is determined to be strong; when the comprehensive support capability index is greater than or equal to 0.8 and less than 0.9, the comprehensive support capability level is determined to be good; when the comprehensive support capability index is greater than or equal to 0.7 and less than 0.8, the comprehensive support capability level is determined to be average; when the comprehensive support capability index is less than 0.7, the comprehensive support capability level is determined to be weak.

10. A comprehensive evaluation device for the voltage and frequency support capability of new energy power stations, taking into account equipment health status, characterized in that, include: The data acquisition module is used to acquire the operating status data of various equipment in the new energy power station; A health status evaluation module is used to determine the equipment health index of each device based on the operating status data. The health status correction module is used to correct the equipment health index of each device based on the service time of each device, the electrical distance between each device and the grid connection point of the new energy power station, and the spatial attenuation coefficients corresponding to reactive power support, active power support and inertia support, so as to obtain the comprehensive corrected health index of each device for reactive power support, active power support and inertia support respectively. The support capability evaluation module is used to determine the available reactive power support capacity of the new energy power station based on the comprehensive corrected health index of each device for reactive power support and the reactive power support capacity of the corresponding device; to determine the available active power support capacity of the new energy power station based on the comprehensive corrected health index of each device for active power support and the active power support capacity of the corresponding device; to determine the equivalent inertia of the new energy power station based on the comprehensive corrected health index of each device for inertia support and the inertia of the corresponding device; and to determine the voltage support capability index, frequency support capability index, and inertia support capability index of the new energy power station based on the available reactive power support capacity, the available active power support capacity, and the equivalent inertia, respectively. The comprehensive evaluation module is used to perform weighted fusion of the voltage support capability index, the frequency support capability index, and the inertia support capability index to obtain the comprehensive support capability evaluation result of the new energy power station.

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