A configuration method of a distributed phase modifier

Abstract

The application discloses a configuration method of a distributed phase modifier. The technical scheme is as follows: determining the minimum value and the change rate of the power factor of each new energy cluster at the side of a collecting station, and comparing the minimum value and the change rate with corresponding judgment thresholds respectively; according to the comparison results, the new energy clusters are divided into two groups, for one group satisfying the threshold requirements in the minimum value and the change rate, using the self-impedance and the equivalent impedance of the power grid as the analysis calculation amount, calculating the upper limit value of the influence of each new energy cluster in the group on the power grid voltage; for the other group, using the judgment threshold of the minimum value of the power factor and the equivalent impedance of the power grid as the analysis calculation amount, calculating the upper limit value of the influence of each new energy cluster in the group on the power grid voltage; solving the equivalent reactance of the power grid access formed by the phase modifier; and according to the equivalent reactance of the power grid access, combining the type of the phase modifier, obtaining the access requirements of the phase modifier. The configuration method can effectively suppress voltage fluctuation.

Description

Technical Field

[0001] This invention belongs to the field of synchronous condenser technology, and in particular to a method for configuring distributed synchronous condensers. Background Technology

[0002] Distributed synchronous condensers are crucial equipment supporting the grid connection and transmission of new energy sources. During the construction of new power systems, challenges arise such as low inertia levels, insufficient transient synchronization support capabilities, and significant voltage / frequency oscillation risks. Achieving an ideal synchronous voltage source, strong overload and instantaneous response, and mechanical inertia support capabilities based on electromagnetic induction and electromechanical coupling rather than algorithms is a vital guarantee for the long-term stability of the power system.

[0003] Synchronous condensers have instantaneous reactive power support capabilities. They can provide instantaneous reactive power support to the power grid system based on their autonomous reactive power response characteristics when a grid fault or disturbance occurs, thus avoiding the disconnection of new energy sources from the grid due to transient voltage problems.

[0004] Synchronous condensers possess the ability to improve short-circuit ratio and support mechanical inertia. Faults such as subsynchronous oscillations in Hami, Xinjiang, indicate that the capacity of new energy access and the support capability of short-circuit ratio must be matched. Insufficient inertia level under the impact of high power deficit will seriously affect the frequency stability of the system. Synchronous condensers can improve the system strength and stability and suppress system oscillations.

[0005] The massive grid connection of distributed photovoltaic power will lead to a mismatch between the capacity and spatiotemporal characteristics of power supply and load, an increasing number of backfeeding phenomena, a "tidal" power flow change in the main and distribution networks, and frequent occurrences of voltage over-limit and fluctuation problems.

[0006] For impact loads such as distributed renewable energy and charging piles, a centralized current collection and high-voltage grid connection method is adopted to absorb them. In addition, distributed synchronous condensers are installed in substations with a high proportion of renewable energy access. This can avoid overvoltage caused by voltage exceeding limits, smoothing voltage fluctuations, and suppressing overvoltage caused by the switching of impact loads.

[0007] Currently, distributed synchronous condensers are mainly used in large-scale new energy power plants and their collection stations. The basic principle of the configuration method is to increase the short-circuit ratio of multiple power plants to the national standard requirement. There is still a lack of configuration methods for voltage fluctuation suppression. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to overcome the defects of the prior art. It will carry out differentiated calculations based on the power factor of each new energy cluster collection station, and provide a distributed synchronous condenser configuration method for voltage fluctuation suppression based on self-impedance, grid equivalent impedance, new energy cluster power, power factor, line impedance and grid voltage.

[0009] Therefore, the present invention adopts the following technical solution: a method for configuring a distributed synchronous condenser, comprising the following steps: a) Analyze the historical data of the power factor of each new energy cluster to determine the minimum power factor and the rate of change of the power factor of each new energy cluster at the collection station. b) Based on step a), compare the minimum power factor and rate of change of each new energy cluster with the corresponding judgment thresholds respectively; c) Based on the comparison results in step b), classify the new energy clusters. The new energy clusters that meet the threshold requirements for both the minimum power factor and the rate of change are in one group, and the remaining new energy clusters are in another group. d) According to step c), for a group in which both the minimum power factor and the rate of change meet the threshold requirements, the equivalent impedance and self-impedance of the power grid after the addition of a synchronous condenser are used as the analytical calculation quantities for each new energy cluster in this group. e) According to step c), for a group whose minimum power factor or rate of change does not meet the threshold requirement, each new energy cluster in this group uses the judgment threshold of the minimum power factor in step b) and the equivalent impedance of the power grid after adding a synchronous condenser as the analysis and calculation quantity. f) Calculate the upper limit of the impact of each new energy cluster on the grid voltage in this group based on the analysis and calculation of step d); g) Calculate the upper limit of the impact of each new energy cluster on the grid voltage in this group based on the analysis and calculation of step e); h) Calculate the upper limit of the grid voltage fluctuation rate based on the results obtained in steps f) and g), set the upper limit of the voltage fluctuation rate to be equal to the required value, and solve for the grid access equivalent reactance formed by adding a synchronous condenser. i) Based on the grid access equivalent reactance obtained in step h), and combined with the type of synchronous condenser, the access requirements of the synchronous condenser are obtained.

[0010] Furthermore, in step i), when the synchronous condenser connected to the grid is a direct-connected synchronous condenser, the equivalent reactance of the grid connection obtained in step h) is the equivalent reactance requirement of the direct-connected synchronous condenser required to meet the voltage fluctuation rate requirement. When the grid is connected to a conventional synchronous condenser-transformer unit, based on the grid voltage level, calculate half of the per-unit value of the grid connection equivalent reactance obtained in step h). This is the per-unit value requirement of the synchronous condenser equivalent reactance in the conventional synchronous condenser-transformer unit to meet the voltage fluctuation rate requirement.

[0011] Furthermore, the configuration method of the distributed synchronous condenser also includes: for the distributed new energy collection station, using per-unit values ​​to calculate the product of the rated output active power of each new energy cluster and the line impedance amplitude, selecting the new energy cluster with the largest product to carry out multi-site short-circuit ratio calculation, and if it meets the requirements, then the other sites also meet the requirements.

[0012] Furthermore, in step a), each new energy clusterP 1. P 2、…、 P N The power factors at the collection station side are cos i 1. cosplay i 2、…、cos i N During the operating time, the minimum power factor of each new energy cluster at the collection station side is calculated as cos i 1min cos i 2min ...cos i Nmin The power factor change rate of each new energy cluster at the collection station side was calculated as follows: d cos i 1 / dt , d cos i 2 / dt … d cos i N / dt .

[0013] Furthermore, in step b), the minimum power factor cos... i 1min cos i 2min ...cos i Nmin and power factor change rate d cos i 1 / dt , d cos i 2 / dt … d cos i N / dt Respectively with the judgment threshold A and B In comparison, among them A and B It is a constant, determined according to standard requirements and scenario needs.

[0014] Furthermore, in step c), for the first... n New energy cluster P n ,1≤ n ≤ N cos i nmin and d cos in / dt If the following expression is satisfied, then P n Belongs to set P V ,otherwise P n Belongs to set P K ; .

[0015] Furthermore, in step d), for the set P V For each new energy cluster in the dataset, calculate the self-impedance and grid equivalent impedance of each new energy cluster; in step e), for the set... P K For each new energy cluster, calculate the equivalent impedance of the power grid in step b).

[0016] Furthermore, in step f), the set P V China's new energy clusters, for grid voltage Impact , by set P V The upper limit is determined by all elements in the set, and is calculated as follows: , For the first time during the running time New energy cluster Maximum output power The equivalent impedance of the power grid after installing a synchronous condenser, Indicates the first New energy cluster The phase angle of self-impedance.

[0017] Furthermore, in step g), the set P K China's new energy clusters, for grid voltage Impact , by set P K The upper limit is determined by all elements in the set, and is calculated as follows: , For the first time during the running time k New energy cluster P k Maximum output power The equivalent impedance of the power grid after installing a synchronous condenser, This indicates the angle of the equivalent impedance of the power grid after the installation of a synchronous condenser.

[0018] Furthermore, in step h), the upper limit of the voltage fluctuation rate is determined by the equivalent reactance of the grid connection formed by the addition of a synchronous condenser. The decision is made, and the upper limit of voltage fluctuation rate is set to the required value. C Equal, solve : ,

[0019]

[0020] In the formula, The equivalent impedance of the power grid before the installation of the synchronous condenser.

[0021] The beneficial effects of this invention are as follows: Based on self-impedance, equivalent grid impedance, power of new energy clusters, power factor, line impedance, and grid voltage, this invention performs differentiated calculations according to the power factor of each new energy cluster's collection station, realizing a distributed synchronous condenser configuration that can effectively suppress voltage fluctuations, and facilitating the distributed new energy consumption method of centralized current collection and high-voltage grid connection; this invention is of great significance for the synchronous condenser configuration of distributed new energy collection stations, and can also be extended to large-scale new energy power plant collection stations. Attached Figure Description

[0022] The accompanying drawings used in the description of the embodiments of the present invention will be briefly introduced below.

[0023] Figure 1 This is a flowchart illustrating the configuration method of the distributed synchronous condenser of the present invention. Figure 2 This is a schematic diagram of a typical equivalent circuit in an embodiment of the present invention. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0025] Example 1 This embodiment provides a configuration method for a distributed camera adjustment mechanism, such as... Figure 1 As shown.

[0026] New energy cluster P 1. P 2、…、 P 5. Centralized power collection and grid connection: Conventional synchronous condenser-transformer units are installed at the collecting station to suppress voltage fluctuations. A typical circuit diagram is shown below. Figure 2 As shown, Figure 2 middle, U c This represents the equivalent ideal voltage source for adjusting the camera. U sThis represents the equivalent ideal voltage source of the power grid system, Δ. I s Δ represents the change in the sum of the grid-connected currents of each new energy cluster. I N Indicates the first N The change in grid-connected current of each new energy cluster, Z LN Indicates the first N Line impedance of a new energy cluster.

[0027] This embodiment uses the following steps to determine the configuration requirements of the camera condenser.

[0028] Various new energy clusters P 1. P 2、…、 P 5. The power factors at the collection station side are cos i 1. cosplay i 2、…、cos i 5. Calculate the minimum power factor of each new energy cluster at the collection station during the operating time, which are respectively cos i 1min cos i 2min ...cos i 5min Calculate the power factor change rate of each new energy cluster at the collection station side, respectively. d cos i 1 / dt , d cos i 2 / dt … d cos i 5 / dt , t Indicates time, in seconds.

[0029] cos i 1min cos i 2min ...cos i 5min and d cos i 1 / dt , d cos i 2 / dt … d cos i 5 / dt With thresholds of 0.95 and , respectively B In comparison, among them B It is a constant, and in this embodiment it is taken as 0.1.

[0030] For 1≤ n ≤5, cos i nmin and d cos i n / dt If equation 1 is satisfied, then P n Belongs to set P V ,otherwise P n Belongs to set P K , (1) in P 1. P 2. P 3 belongs to set P V , P 4. P 5 belongs to set P K .

[0031] New energy cluster P 1. P 2. P 3. Regarding the grid voltage Impact ,Depend on P 1. P 2. P 3. As determined by the above, under normal conditions, the phase difference of the voltages at both ends of the line can be considered small and can be ignored. The vertical component is shown in Equation 2: (2) In the formula, Indicates the first The change in grid-connected current of a new energy cluster Indicates the first The change in power of each new energy cluster The equivalent impedance of the power grid after installing a synchronous condenser, This indicates the angle of the equivalent impedance of the power grid after the installation of a synchronous condenser. (1≤ v ≤3) is a new energy cluster P 1. P 2. P The phase angle of the line impedance of 3.

[0032] (3) (4) (5) (6) According to equations 3 to 6, the new energy cluster P 1. P 2. P 3 pairs of grid voltages The upper limit of the impact can be approximated as: , In the formula, For the first time during the running time New energy cluster Maximum output power.

[0033] Similarly, new energy clusters P 4. P 5. Regarding the grid voltage Impact ,Depend on P 4. P 5. Jointly decided, P 4. P 5. There are operating conditions that do not meet the minimum power factor and its fluctuation rate requirements at the collection station. Considering the addition of synchronous condensers to distributed renewable energy collection stations, the unit capacity margin is relatively large, allowing them to operate in a non-hot standby state, adjusting reactive power in real time to improve the power factor, especially for direct-connected synchronous condensers directly connected to the grid. In this case, the renewable energy cluster... P 4. P 5. The upper limit of the impact on grid voltage is: .

[0034] The upper limit of voltage fluctuation rate is determined by the grid connection equivalent reactance formed by the addition of a synchronous condenser. As shown in Equation 7, the upper limit of the voltage fluctuation rate is set to the required value. C Equal, solve ; (7) (8) (9) In the formula, The equivalent reactance of the power grid connection formed by the installation of a synchronous condenser, among which The equivalent impedance of the power grid before installing the synchronous condenser, To adjust the equivalent reactance of the camera body, This is the equivalent reactance of the step-up transformer.

[0035] The stator rated voltage of the synchronous condenser is 10kV, the rated voltage of the step-up transformer is 35kV, and the equivalent reactance of the grid connection for installing the synchronous condenser is... The per-unit value is 0.6, and 0.3 (0.6 ÷ 2) is the per-unit value requirement of the equivalent reactance of the synchronous condenser in the conventional synchronous condenser-transformer group to meet the voltage fluctuation rate requirement.

[0036] P 1. P 2、…、 P The rated output active power of 5 is P 1o , P 2o … P 5o Using per-unit values, the product of the rated output active power and the line impedance amplitude of each new energy cluster is calculated. The product value of the third new energy cluster is the largest. The short-circuit ratio of the multiple stations of this new energy cluster is calculated and meets the standard requirements. The other new energy stations also meet the requirements.

[0037] Example 2 This embodiment provides a configuration method for a distributed camera adjustment mechanism, such as... Figure 1 As shown.

[0038] New energy cluster P 1. P 2、…、 P 5. Centralized power collection and grid connection; the collecting station is equipped with a direct-connected synchronous condenser to suppress voltage fluctuations. A typical circuit diagram is shown below. Figure 2 As shown.

[0039] This embodiment uses the following steps to determine the configuration requirements of the camera condenser.

[0040] Various new energy clusters P 1. P 2、…、 P 5. The power factors at the collection station side are cos i 1. cosplay i 2、…、cos i 5. Calculate the minimum power factor of each new energy cluster at the collection station during the operating time, which are respectively cos i 1min cos i 2min ...cos i 5min Calculate the power factor change rate of each new energy cluster at the collection station side, respectively. d cos i 1 / dt , d cos i 2 / dt … d cos i 5 / dt ,t Indicates time, in seconds.

[0041] cos i 1min cos i 2min ...cos i 5min and d cos i 1 / dt , d cos i 2 / dt … d cos i 5 / dt With thresholds of 0.95 and , respectively B In comparison, among them B It is a constant, and in this embodiment it is taken as 0.1.

[0042] For 1≤ n ≤5, cos i nmin and d cos i n / dt If equation 1 is satisfied, then P n Belongs to set P V ,otherwise P n Belongs to set P K , (1) in, P 1. P 2. P 3 belongs to set P V , P 4. P 5 belongs to set P K .

[0043] New energy cluster P 1. P 2. P 3. Regarding the grid voltage Impact ,Depend on P 1. P 2. P 3. As determined by the above, under normal conditions, the phase difference of the voltages at both ends of the line can be considered small and can be ignored. The vertical component is shown in Equation 2, where f Lv(1≤ v ≤3) is a new energy cluster P 1. P 2. P The phase angle of the line impedance of 3.

[0044] (2) New energy cluster P 1. P 2. P 3. Regarding the grid voltage The upper limit of the impact can be approximated as: .

[0045] Similarly, new energy clusters P 4. P 5. Regarding the grid voltage The impact is ,Depend on P 4. P 5. Jointly decided, P 4. P 5. There are operating conditions that do not meet the minimum power factor and its fluctuation rate requirements at the collection station. Considering the addition of synchronous condensers to distributed renewable energy collection stations, the unit capacity margin is relatively large, allowing them to operate in a non-hot standby state, adjusting reactive power in real time to improve the power factor, especially for direct-connected synchronous condensers directly connected to the grid. In this case, the renewable energy cluster... P 4. P 5. The upper limit of the impact on grid voltage is: .

[0046] The upper limit of voltage fluctuation rate is determined by the grid connection equivalent reactance formed by the addition of a synchronous condenser. As shown in Equation 7, the upper limit of the voltage fluctuation rate is set to the required value. C Equal, solve ; (7) (10) (9) The equivalent reactance of the power grid connection formed by adding a synchronous condenser The calculated value is the equivalent reactance requirement of the direct-connected synchronous condenser that needs to be connected to meet the voltage fluctuation rate requirement.

[0047] P 1. P 2、…、 P The rated output active power of 5 is P 1o , P 2o … P5o Using per-unit values, the product of the rated output active power and the line impedance amplitude of each new energy cluster is calculated. The product value of the third new energy cluster is the largest. The short-circuit ratio of the multiple stations of this new energy cluster is calculated and meets the standard requirements. The other new energy stations also meet the requirements.

[0048] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention.

Claims

1. A method of configuring a distributed phase modifier, the method comprising: Including the following steps: a) Analyze the historical data of the power factor of each new energy cluster to determine the minimum power factor and the rate of change of the power factor of each new energy cluster at the collection station. b) Based on step a), compare the minimum power factor and rate of change of each new energy cluster with the corresponding judgment thresholds respectively; c) Based on the comparison results in step b), classify the new energy clusters. The new energy clusters that meet the threshold requirements for both the minimum power factor and the rate of change are in one group, and the remaining new energy clusters are in another group. d) According to step c), for a group in which both the minimum power factor and the rate of change meet the threshold requirements, the equivalent impedance and self-impedance of the power grid after the addition of a synchronous condenser are used as the analytical calculation quantities for each new energy cluster in this group. e) According to step c), for a group whose minimum power factor or rate of change does not meet the threshold requirement, each new energy cluster in this group uses the judgment threshold of the minimum power factor in step b) and the equivalent impedance of the power grid after adding a synchronous condenser as the analysis and calculation quantity. f) Calculate the upper limit of the impact of each new energy cluster on the grid voltage in this group based on the analysis and calculation of step d); g) Calculate the upper limit of the impact of each new energy cluster on the grid voltage in this group based on the analysis and calculation of step e); h) Calculate the upper limit of the grid voltage fluctuation rate based on the results obtained in steps f) and g), set the upper limit of the voltage fluctuation rate to be equal to the required value, and solve for the grid access equivalent reactance formed by adding a synchronous condenser. i) Based on the grid access equivalent reactance obtained in step h), and combined with the type of synchronous condenser, the access requirements of the synchronous condenser are obtained.

2. The method for configuring a distributed synchronous condenser according to claim 1, characterized in that, In step i), When the synchronous condenser connected to the power grid is a direct-connected synchronous condenser, the equivalent reactance of the power grid connection obtained in step h) is the equivalent reactance requirement of the direct-connected synchronous condenser to meet the voltage fluctuation rate requirement. When the grid is connected to a conventional synchronous condenser-transformer unit, based on the grid voltage level, calculate half of the per-unit value of the grid connection equivalent reactance obtained in step h). This is the per-unit value requirement of the synchronous condenser equivalent reactance in the conventional synchronous condenser-transformer unit to meet the voltage fluctuation rate requirement.

3. The method of claim 2, wherein, It also includes: for distributed new energy collection stations, the product of the rated output active power of each new energy cluster and the line impedance amplitude is calculated using per-unit values. The new energy cluster with the largest product is selected to carry out multi-site short-circuit ratio calculation. If it meets the requirements, then the other sites also meet the requirements.

4. The method for configuring a distributed synchronous condenser according to claim 1, characterized in that, In step a), each new energy cluster P 1. P 2、…、 P N The power factors at the collection station side are cos θ 1. cosplay θ 2、…、cos θ N During the operating time, the minimum power factor of each new energy cluster at the collection station side is calculated as cos θ 1min cos θ 2min ...cos θ Nmin The power factor change rate of each new energy cluster at the collection station side was calculated as follows: d cos θ 1 / dt , d cos θ 2 / dt … d cos θ N / dt .

5. The method of claim 4, wherein, In step b), the minimum power factor cos θ 1min cos θ 2min ...cos θ Nmin and power factor change rate d cos θ 1 / dt , d cos θ 2 / dt … d cos θ N / dt Respectively with the judgment threshold A and B In comparison, among them A and B It is a constant, determined according to standard requirements and scenario needs.

6. The method of claim 5, wherein, In step c), for the first n New energy cluster P n ,1≤ n ≤ N cos θ nmin and d cos θ n / dt If the following expression is satisfied, then P n Belongs to set P V ,otherwise P n Belongs to set P K ; 。 7. The method of claim 5, wherein, In step d), for the set P V For each new energy cluster in the dataset, calculate the self-impedance and grid equivalent impedance of each new energy cluster; in step e), for the set... P K For each new energy cluster, calculate the equivalent impedance of the power grid in step b).

8. The method of claim 7, wherein, In step f), the set P V China's new energy clusters, for grid voltage Impact , by set P V The upper limit is determined by all elements in the set, and is calculated as follows: , For the first time during the running time New energy cluster Maximum output power The equivalent impedance of the power grid after installing a synchronous condenser, Indicates the first New energy cluster The phase angle of self-impedance.

9. The method of claim 7, wherein, In step g), the set P K China's new energy clusters, for grid voltage Impact , by set P K The upper limit is determined by all elements in the set, and is calculated as follows: , For the first time during the running time k New energy cluster P k Maximum output power The equivalent impedance of the power grid after installing a synchronous condenser, This indicates the angle of the equivalent impedance of the power grid after the installation of a synchronous condenser.

10. The method of claim 9, wherein, In step h), the upper limit value of the voltage fluctuation rate is determined by the grid access equivalent reactance formed by the addition of the phase modifier and the voltage fluctuation rate upper limit value is made equal to the required value C , and the solution is determined ， In the formula, Zgrid is the equivalent impedance of the power grid before the phase modifier is installed.

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