A method for smoothing power shortage by considering both wind turbine and grid-side energy storage

Abstract

The present invention provides a method for stabilizing power shortages while taking into account both wind turbine-side and grid-side energy storage. The background of the method is that multiple wind farms are integrated into the power grid, and some wind farms are equipped with energy storage on the machine side. When the power grid has a power shortage, a method for stabilizing power shortages is proposed in which wind turbine-side energy storage, wind grid-side energy storage, and wind turbines jointly provide power support. First, the effectiveness of power support is evaluated for wind farm nodes with machine-side energy storage, wind farm nodes without machine-side energy storage, and wind turbine grid-side energy storage, and the real-time power support capacity is calculated. Then, the grid-side energy storage power station is selected as a balancing converter station, and upper-layer unified power dispatch is performed for multiple wind farm nodes and grid-side energy storage, and finally the power shortage of the power grid is stabilized. Compared with the traditional single method, the method proposed by the present invention has higher reliability and effectiveness.

Description

Technical Field

[0001] The present invention relates to the technical field of coordinated control of electric power systems, and in particular to a method for smoothing power shortages while taking both wind turbine-side and grid-side energy storage into consideration. Background Art

[0002] As a renewable energy source, wind power generation has significant volatility, which poses a challenge to the stable operation of the power grid. In order to reduce the impact of wind farm output power fluctuations on the power grid and realize large-scale wind power grid connection, an effective smoothing method is needed. The power shortage smoothing method considering wind turbine side and grid side energy storage aims to improve the output quality of wind power and ensure the stable operation of the power system through reasonable energy storage configuration and control strategy. At present, domestic and foreign scholars have conducted a lot of research on the problem of power shortage smoothing of wind farm station grid connection. Some are mainly based on the self-regulation control of wind turbines, and adjust the operating state of wind turbines through methods such as pitch angle control and DC bus voltage control to smooth power fluctuations. However, it should be noted that these methods may affect the efficiency of wind turbines in capturing wind energy, so the pros and cons need to be weighed. Some only consider the wind turbine grid side energy storage power station, or only consider the wind turbine machine side energy storage power station. With the increase of large-scale wind power clusters in the region and the increase in the proportion of regional wind power, the coordinated control strategy of power mutual assistance of multiple wind farms and multiple energy storage units should be considered at the same time to improve the stability of regional power shortage smoothing. The present invention aims to propose a wind power-wind turbine side energy storage-wind grid side energy storage power coordination control method for smoothing the power shortage of wind farm stations connected to the grid. The method combines the adjustment ability of the wind turbine itself, the rapid response characteristics of the energy storage device and the dispatching strategy of the grid to achieve effective smoothing of wind power shortages. Specifically, it is to configure energy storage devices on the wind turbine side and the grid side respectively, and according to the real-time fluctuation of wind power, coordinate the charging and discharging process of the energy storage device through an intelligent control strategy, so as to achieve the smoothing of wind power shortages. The technical solution of the present invention is of great significance for promoting the healthy development of the wind power industry and ensuring the stable operation of the power grid. Summary of the invention

[0003] In view of this, an object of the present invention is to provide a power shortage smoothing method that takes into account both wind turbine-side and grid-side energy storage, so as to at least solve the above problems.

[0004] The technical solution adopted by the present invention is as follows:

[0005] A method for smoothing power shortage by simultaneously considering energy storage on a wind turbine side and a grid side, the method comprising the following steps:

[0006] S1. Integrate wind turbine side energy storage, wind grid side energy storage and wind turbine nodes;

[0007] S2, calculating the power effectiveness of wind turbine side energy storage, wind grid side energy storage and wind turbine node under power shortage state;

[0008] S3, select the energy storage on the wind grid side as the balancing converter station;

[0009] S4. The wind turbine side energy storage, wind grid side energy storage and wind turbine group nodes are uniformly dispatched through the balancing converter station.

[0010] Further, in step S1, the nodes of wind turbine side energy storage, wind grid side energy storage and wind turbine group include wind turbine group, wind turbine side and wind grid side.

[0011] Further in step S2, the power effectiveness includes wind turbine dispatchable energy assessment, wind turbine side dispatchable energy assessment, side dispatchable energy aggregation, wind grid side dispatchable energy assessment,

[0012] The dispatchable energy assessment of wind turbines is as follows:

[0013] By calculating the formula: Calculate the mechanical power of a wind turbine ,in, is the fan rotor radius, is the air resistance coefficient, is the speed. When there is a power shortage, the additional power generated by the wind farm is affected by the grid connection point voltage and instantaneous wind speed. The additional support power that can be provided is ,in, is the wind power effectiveness utilization coefficient, then the real-time dispatchable power of wind farm station n is ;

[0014] The specific evaluation of the dispatchable energy on the wind turbine side is as follows:

[0015] When the battery system of the energy storage power station accepts the dispatching task, the total power of each battery system charging and discharging should be equal to the dispatching task. By setting the total dispatchable energy of the wind turbine side energy storage to ,set up is the wind turbine side energy storage effectiveness utilization coefficient, which is taken as the ratio of the power that the wind turbine side energy storage can provide to the rated capacity of the wind turbine side energy storage at the time of power shortage. The total real-time energy that can be dispatched by the wind turbine side energy storage is , then the real-time dispatchable power of wind farm station n is The battery's state of charge (SOC) represents the ratio of the battery's remaining capacity to its rated capacity.

[0016]

[0017] represents the SOC of the energy storage on the side of the i-th wind turbine; represents the lower limit of the energy storage SOC on the side of the i-th wind turbine; represents the upper limit of the energy storage SOC on the side of the i-th wind turbine;

[0018] The specific energy aggregation of machine-side scheduling is as follows:

[0019] The instantaneous power margin of the wind farm itself and the instantaneous power scheduling margin of the wind farm side energy storage are considered as a whole.

[0020]

[0021] The restriction is , while taking into account wind turbines without wind turbine energy storage

[0022] The real-time dispatchable power is ;

[0023] The dispatchable energy evaluation on the wind power grid side is as follows:

[0024] When the battery system of the energy storage power station accepts a dispatching task, the total power of each battery system charging and discharging should be equal to the dispatching task. Assume that the total dispatchable energy of the generator-side energy storage is , by setting is the wind grid side energy storage effectiveness utilization coefficient, then the real-time dispatchable power on the wind grid side is , and exist simultaneously

[0025]

[0026] Indicates the SOC of energy storage on the wind grid side; Indicates the lower limit of SOC of energy storage on the wind power grid side; Indicates the upper limit of the energy storage SOC on the wind grid side.

[0027] Further, in step S4, the wind turbine side energy storage, wind grid side energy storage and wind turbine group nodes are uniformly dispatched through the balancing converter station as follows:

[0028] By sorting the real-time dispatchable power in the dispatchable energy evaluation of wind turbines, the dispatchable energy evaluation of wind turbines on the machine side, the dispatchable energy aggregation of the machine side, and the dispatchable energy evaluation of the wind grid side, and by setting the number of nodes to N, it can be divided into m groups, where m ≥ 2 and each node is included in only one group. The grouping can be expressed as follows

[0029]

[0030] Based on the clustering algorithm, the representative matrix R = [r(i,k)]N×N and the fitness matrix A=[a(i,k)]N×N are initialized to 0, N is the number of all samples, r(i,k) represents the degree of representativeness of the kth sample as the class representative point of the i-th sample, and a(i,k) represents the degree of suitability of the i-th sample to select the kth sample as the class representative sample. , select λ as the consistency variable of the consistency algorithm, and update its consistency variable by exchanging information with neighbors, so that the consistency variables of all agents in the network converge to a unified value, that is, λV1=λV2= λV n , to achieve optimal power scheduling, where the scheduling constraints are:

[0031] And at the same time satisfy the voltage constraint of the export node,

[0032] The voltage constraints of each node meet the following conditions:

[0033]

[0034] and They represent the minimum and maximum values ​​of the voltage at node i, respectively. is the confidence level of the voltage constraint. The confidence interval gives the degree of credibility of the measured value of the measured parameter.

[0035] The power constraints of each branch meet the following conditions:

[0036]

[0037] represents the maximum transmission power allowed for branch i; It indicates the confidence of the power constraint. The power of each branch is within the constraint condition to prevent the branch power from being too large and causing collapse due to excessive power.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] The present invention proposes a power shortage stabilization method that considers both wind turbine side and grid side energy storage. When the power grid has a power shortage, a power shortage stabilization method is proposed in which wind turbine side energy storage, grid side energy storage, and wind turbines jointly provide power support. The wind farm station nodes with machine side energy storage and wind farm station nodes without machine side energy storage are evaluated for power support effectiveness, and the real-time power support capacity is calculated. After that, the grid side energy storage power station is selected as the balancing converter station, and the upper layer unified power dispatch is performed on multiple wind farm station nodes and grid side energy storage, and finally the power shortage stabilization of the power grid is realized. Compared with the traditional single method, the method proposed in this article has higher reliability and effectiveness. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only preferred embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0041] Figure 1 It is a schematic diagram of the overall process of a power shortage smoothing method that takes into account both wind turbine side and grid side energy storage, as proposed in an embodiment of the present invention.

[0042] Figure 2 It is a schematic diagram of the overall dispatchable energy overview of a power shortage smoothing method that takes into account both wind turbine-side and grid-side energy storage, as proposed in an embodiment of the present invention. DETAILED DESCRIPTION

[0043] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The enumerated embodiments are only used to explain the present invention and are not used to limit the scope of the present invention.

[0044] The innovation of the present invention lies in that the existing scheduling and inventive methods do not take the example of wind turbine grid-side energy storage, machine-side energy storage, and wind turbines themselves to perform power mutual assistance and coordinated scheduling, and do not take master-slave scheduling, with grid-side energy storage as the main scheduling, machine-side energy storage and wind turbine clustering as slave scheduling, and a precedent of scheduling by a consistency algorithm after clustering analysis of the machine-side energy storage and the wind turbine nodes themselves.

[0045] Reference Figure 1 and Figure 2 The present invention provides a method for smoothing power shortage by taking into account both wind turbine side and grid side energy storage, the method comprising the following steps:

[0046] S1. Integrate wind turbine side energy storage, wind grid side energy storage and wind turbine nodes;

[0047] S2, calculating the power effectiveness of wind turbine side energy storage, wind grid side energy storage and wind turbine node under power shortage state;

[0048] S3, select the energy storage on the wind grid side as the balancing converter station;

[0049] S4. The wind turbine side energy storage, wind grid side energy storage and wind turbine group nodes are uniformly dispatched through the balancing converter station.

[0050] In step S1 , the wind turbine side energy storage, wind grid side energy storage and wind turbine nodes include wind turbines, wind turbine side and wind grid side.

[0051] Exemplarily, in order to achieve the smoothing of power shortage in the power grid, by integrating the wind turbine side energy storage, the wind grid side energy storage and the wind turbine, wind turbine side and wind grid side nodes of the wind turbine, and calculating their power effectiveness, the wind grid side energy storage is selected as the balancing converter station for unified power scheduling, thereby effectively smoothing the power shortage. This method has high flexibility and accuracy and can adapt to changes in power demand under different circumstances.

[0052] In step S2, power effectiveness includes wind turbine dispatchable energy assessment, wind turbine side dispatchable energy assessment, side dispatchable energy aggregation, and wind grid side dispatchable energy assessment.

[0053] The dispatchable energy assessment of wind turbines is as follows:

[0054] By calculating the formula: Calculate the mechanical power of a wind turbine ,in, is the fan rotor radius, is the air resistance coefficient, is the speed. When there is a power shortage, the additional power generated by the wind farm is affected by the grid connection point voltage and instantaneous wind speed. The additional support power that can be provided is ,in, is the wind power effectiveness utilization coefficient, then the real-time dispatchable power of wind farm station n is ;

[0055] The specific evaluation of the dispatchable energy on the wind turbine side is as follows:

[0056] When the battery system of the energy storage power station accepts the dispatching task, the total power of each battery system charging and discharging should be equal to the dispatching task. By setting the total dispatchable energy of the wind turbine side energy storage to ,set up is the wind turbine side energy storage effectiveness utilization coefficient, which is taken as the ratio of the power that the wind turbine side energy storage can provide to the rated capacity of the wind turbine side energy storage at the time of power shortage. The total real-time energy that can be dispatched by the wind turbine side energy storage is , then the real-time dispatchable power of wind farm station n is The battery's state of charge (SOC) represents the ratio of the battery's remaining capacity to its rated capacity.

[0057]

[0058] represents the SOC of the energy storage on the side of the i-th wind turbine; represents the lower limit of the energy storage SOC on the side of the i-th wind turbine; represents the upper limit of the energy storage SOC on the side of the i-th wind turbine;

[0059] The specific energy aggregation of machine-side scheduling is as follows:

[0060] The instantaneous power margin of the wind farm itself and the instantaneous power scheduling margin of the wind farm side energy storage are considered as a whole.

[0061]

[0062] The restriction is , while taking into account wind turbines without wind turbine energy storage

[0063] The real-time dispatchable power is ;

[0064] The dispatchable energy evaluation on the wind power grid side is as follows:

[0065] When the battery system of the energy storage power station accepts a dispatching task, the total power of each battery system charging and discharging should be equal to the dispatching task. Assume that the total dispatchable energy of the generator-side energy storage is , by setting is the wind grid side energy storage effectiveness utilization coefficient, then the real-time dispatchable power on the wind grid side is , and exist simultaneously

[0066]

[0067] Indicates the SOC of energy storage on the wind grid side; Indicates the lower limit of SOC of energy storage on the wind power grid side; Indicates the upper limit of the energy storage SOC on the wind grid side.

[0068] In step S4, the wind turbine side energy storage, wind grid side energy storage and wind turbine group nodes are uniformly dispatched through the balancing converter station as follows:

[0069] By sorting the real-time dispatchable power in the dispatchable energy evaluation of wind turbines, the dispatchable energy evaluation of wind turbines on the machine side, the dispatchable energy aggregation of the machine side, and the dispatchable energy evaluation of the wind grid side, and by setting the number of nodes to N, it can be divided into m groups, where m ≥ 2 and each node is included in only one group. The grouping can be expressed as follows

[0070]

[0071] Based on the clustering algorithm, the representative matrix R = [r(i,k)]N×N and the fitness matrix A=[a(i,k)]N×N are initialized to 0, N is the number of all samples, r(i,k) represents the degree of representativeness of the kth sample as the class representative point of the i-th sample, and a(i,k) represents the degree of suitability of the i-th sample to select the kth sample as the class representative sample. , select λ as the consistency variable of the consistency algorithm, and update its consistency variable by exchanging information with neighbors, so that the consistency variables of all agents in the network converge to a unified value, that is, λV1=λV2= λV n , to achieve optimal power scheduling, where the scheduling constraints are:

[0072] And at the same time satisfy the voltage constraint of the export node,

[0073] The voltage constraints of each node meet the following conditions:

[0074]

[0075] and They represent the minimum and maximum values ​​of the voltage at node i, respectively. is the confidence level of the voltage constraint. The confidence interval gives the degree of credibility of the measured value of the measured parameter.

[0076] The power constraints of each branch meet the following conditions:

[0077]

[0078] represents the maximum transmission power allowed for branch i; It indicates the confidence of the power constraint. The power of each branch is within the constraint condition to prevent the branch power from being too large and causing collapse due to excessive power.

[0079] For example, in the upper system-level control system, the dispatchable energy of the wind power grid side energy storage is selected as the power balancing converter station, and the active power reference values ​​of the other converter stations are directly taken from the power flow dispatching system, while the active power reference value of the power balancing converter station is based on the active power reference values ​​of other converter stations. For a wind power grid-connected system with n dispatchable systems, the active power balancing control strategy requires the upper system-level control system to provide an active power reference signal P to each station control system. ref1 , P ref2 ...P refn-1 and the active power reference signal P of the active power balancing station balance .

[0080]

[0081] The system-level control system updates the active power reference value to each converter station only when the dispatching flow is changed. At other times, each converter station is independently controlled according to the most recently updated active power reference value, and the communication requirements are extremely low. This coordinated control strategy selects the power balancing station as the wind power grid side converter station through the upper control system, actively calculates the required power balance amount according to the dispatching flow of the other converter stations, and sends it to the power balancing station, and actively selects the fixed power control or multi-point voltage control mode according to the power flow direction of each station, realizing active power balance and improving the stability and accuracy of the output power of each converter station.

[0082] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for smoothing power shortages by taking into account both wind turbine-side and grid-side energy storage, characterized in that: The method comprises the following steps: S1. Integrate wind turbine side energy storage, wind grid side energy storage and wind turbine nodes; S2, calculate the power effectiveness of wind turbine side energy storage, wind grid side energy storage and wind turbine node under power shortage state, the power effectiveness is the dispatchable power; S3, select the energy storage on the wind grid side as the balancing converter station; S4. Perform unified power dispatching of wind turbine side energy storage, wind grid side energy storage and wind turbine nodes through the balancing converter station, specifically: By sorting the real-time dispatchable power in the dispatchable energy evaluation of wind turbines, the dispatchable energy evaluation of wind turbines on the machine side, the dispatchable energy aggregation on the machine side, and the dispatchable energy evaluation on the wind grid side, and by setting the number of nodes to N, it can be divided into m groups, where m ≥ 2 and each node is only included in one group. The grouping can be expressed as follows Based on the clustering algorithm, the representative matrix R = [r(i,k)]N×N and the fitness matrix A=[a(i,k)]N×N are initialized to 0, N is the number of all samples, r(i,k) represents the degree of representativeness of the kth sample as the class representative point of the i-th sample, and a(i,k) represents the degree of suitability of the i-th sample to select the kth sample as the class representative sample. , select λ as the consistency variable of the consistency algorithm, and update its consistency variable by exchanging information with neighbors, so that the consistency variables of all agents in the network converge to a unified value, that is, λV1 = λV2 = λV n , to achieve optimal power scheduling, where the scheduling constraints are: And at the same time satisfy the voltage constraint of the export node, The voltage constraints of each node meet the following conditions: and Respectively represent the minimum and maximum values ​​of the voltage at node i, is the confidence level of the voltage constraint. The confidence interval gives the degree of credibility of the measured value of the measured parameter. The power constraints of each branch meet the following conditions: represents the maximum transmission power allowed for branch i; It indicates the confidence of the power constraint. The power of each branch is within the constraint condition to prevent the branch power from being too large and causing collapse due to excessive power.

2. A method for smoothing power shortages by taking into account both wind turbine-side and grid-side energy storage according to claim 1, characterized in that: In step S1 , the wind turbine side energy storage, wind grid side energy storage and wind turbine nodes include wind turbines, wind turbine side and wind grid side.

3. A method for smoothing power shortages by taking into account both wind turbine side and grid side energy storage according to claim 2, characterized in that: In step S2, power effectiveness includes wind turbine dispatchable energy assessment, wind turbine side dispatchable energy assessment, side dispatchable energy aggregation, and wind grid side dispatchable energy assessment. The dispatchable energy assessment of wind turbines is as follows: By calculating the formula: Calculate the mechanical power of a wind turbine ,in, is the fan rotor radius, is the air resistance coefficient, is the speed. When there is a power shortage, the additional power generated by the wind farm is affected by the grid connection point voltage and instantaneous wind speed. The additional support power that can be provided is ,in, is the wind power effectiveness utilization coefficient, then the real-time dispatchable power of wind farm station n is ; The specific evaluation of the dispatchable energy on the wind turbine side is as follows: When the battery system of the energy storage power station accepts the dispatching task, the total power of each battery system charging and discharging should be equal to the dispatching task. By setting the total dispatchable energy of the wind turbine side energy storage to ,set up is the wind turbine side energy storage effectiveness utilization coefficient, which is taken as the ratio of the power that the wind turbine side energy storage can provide to the rated capacity of the wind turbine side energy storage at the time of power shortage. The total real-time energy that can be dispatched by the wind turbine side energy storage is , then the real-time dispatchable power of wind farm station n is The battery's state of charge (SOC) represents the ratio of the battery's remaining capacity to its rated capacity. represents the SOC of the energy storage on the side of the i-th wind turbine; represents the lower limit of the energy storage SOC on the side of the i-th wind turbine; represents the upper limit of the energy storage SOC on the side of the i-th wind turbine; The specific energy aggregation of machine-side scheduling is as follows: The instantaneous power margin of the wind farm itself and the instantaneous power scheduling margin of the wind farm side energy storage are considered as a whole. The restriction is , while taking into account wind turbines without wind turbine energy storage The real-time dispatchable power is ; The dispatchable energy evaluation on the wind grid side is as follows: When the battery system of the energy storage power station accepts the dispatching task, the total power of each battery system charging and discharging should be equal to the dispatching task. Assume that the total dispatchable energy on the wind power grid side is , by setting is the effective utilization coefficient of energy storage on the wind grid side, then the real-time dispatchable power on the wind grid side is , and exist simultaneously Indicates the SOC of energy storage on the wind grid side; Indicates the lower limit of SOC of energy storage on the wind power grid side; Indicates the upper limit of the energy storage SOC on the wind grid side.

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