Power distribution network electric energy quality control method and system based on energy storage adjustable limit

Abstract

The invention provides a power distribution network electric energy quality control method and system based on an energy storage adjustable limit, and belongs to the technical field of power systems, and the method comprises the following steps: collecting parameters of a power distribution network; under the constraint condition, according to the parameters of the power distribution network, respectively calculating the maximum power limit, the voltage waveform distortion influence factor, the overvoltage influence factor and the undervoltage influence factor which can be adjusted by the energy storage device; calculating power quality control influence factors of the power distribution network; and controlling the energy storage device according to the calculation result of the power quality control influence factor of the power distribution network. According to the method, the maximum power limit, the voltage waveform distortion influence factor, the overvoltage influence factor and the undervoltage influence factor which can be adjusted by the energy storage device are calculated by using the parameters of the power distribution network, the power quality control influence factor of the power distribution network is calculated under the constraint of the energy storage adjustable limit, and the energy storage device is controlled; effective control of power quality of the power distribution network is realized, and power quality is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of power systems, and in particular relates to a method and system for controlling power quality of a distribution network based on an adjustable limit of energy storage. Background Art

[0002] With economic development and people's growing living standards, electricity, as a clean, efficient and versatile energy form, plays a vital role in modern society. The exploration of the development of electricity in social production and life is becoming more and more in-depth. In order to ensure the reliability and sustainability of electricity supply, the power industry is gradually diversifying the power generation sources. In addition to traditional fossil fuel power generation, more and more renewable energy sources are being integrated into the power generation system, such as wind power, solar power, hydropower and biomass energy.

[0003] With the increase of distributed power sources and power electronic devices in the distribution network, the number of DC power generation equipment connected to the distribution network continues to increase, and the user's electricity consumption pattern begins to change. The introduction of a large number of power electronic devices will inevitably lead to power quality problems. Common power quality problems are mainly harmonic problems and reactive power shortage problems. The current power quality control method uses the Prony algorithm and the improved Adaline model to achieve harmonic detection for harmonic problems, and compensates the current according to the detection results; for the reactive power shortage problem, the reactive power is detected and the current is compensated to solve the problem of reactive power shortage of power quality. Although the above method can solve the power quality compensation problem to a certain extent, it can usually only compensate for one of the power quality problems, and its reliability and compensation effect need to be improved. Summary of the invention

[0004] In view of the technical problems existing in the prior art, the present invention provides a distribution network power quality control method and system based on an adjustable limit of energy storage, which uses the parameters of the distribution network to calculate the maximum power limit, voltage waveform distortion influence factor, overvoltage influence factor and undervoltage influence factor that can be adjusted by the energy storage device. Under the constraint of the adjustable limit of energy storage, the power quality control influence factor of the distribution network is calculated, the energy storage device is controlled, and the effective control of the power quality of the distribution network is achieved, thereby improving the power quality problem.

[0005] The technical solution adopted by the present invention is: a method for controlling power quality of a distribution network based on an adjustable limit of energy storage, comprising the following steps:

[0006] Collect parameters of distribution network;

[0007] Under the constraint condition of the energy storage output limit of the energy storage device of the distribution network, calculating the maximum power limit that can be adjusted by the energy storage device according to the parameters of the distribution network;

[0008] Under the constraints of the output power limit of the power generation equipment of the distribution network and the interval range of the distribution network node voltage, the voltage waveform distortion influence factor, the overvoltage influence factor and the undervoltage influence factor of the distribution network are calculated according to the parameters of the distribution network;

[0009] Under the constraint of the adjustable limit of the energy storage device, the power quality control influence factor of the distribution network is calculated according to the parameters of the distribution network, the maximum power limit that the energy storage device can adjust, the voltage waveform distortion influence factor, the overvoltage influence factor and the undervoltage influence factor;

[0010] The energy storage device is controlled according to the calculation result of the power quality control influencing factor of the distribution network.

[0011] Furthermore, the parameters of the distribution network include the number of transmission lines in the distribution network, the transmission power of the transmission lines in the distribution network, the total number of nodes in the distribution network, the efficiency of the energy storage device, the power output and the power absorption of the energy storage device at each node at time t, the charge state of the energy storage device that outputs power at each node at time t, the charge state of the energy storage device that absorbs power at each node at time t, the rated capacity of the energy storage device, the voltage value of the node under normal conditions, the remaining capacity of the energy storage device at time t, the remaining capacity of the energy storage device at time t+1, the fundamental voltage in the distribution network, the higher harmonic voltage in the distribution network, the harmonic order, the voltage amplitude, the output power of the power generation equipment, the reference value of the output power of the power generation equipment, the voltage deviation membership, the satisfaction coefficient and the weight coefficient α 1 , β 1 , α 2 and β 2 The value of .

[0012] Furthermore, the constraint condition of the energy storage output limit of the energy storage device of the distribution network is that the energy storage output limit of the energy storage device does not exceed the power transmission limit of the distribution network line.

[0013] The constraint condition of the output power limit of the power generation equipment of the distribution network is that the energy storage output limit of the power generation equipment does not exceed the power transmission limit of the distribution network line.

[0014] The power transmission limit of the distribution network line is:

[0015]

[0016] Where P x is the transmission power of the xth transmission line of the distribution network;

[0017] The constraints of the interval range of the distribution network node voltage are:

[0018] V i min ≤V i ≤Vi max ,i∈M

[0019] Where V i , V i min , V i max They represent the voltage value of the node under normal conditions and its minimum and maximum allowed voltage respectively; i represents the i-th node, and M represents the total number of nodes in the distribution network.

[0020] Furthermore, the maximum power limit that the energy storage device can adjust is:

[0021]

[0022] Where P Bi,t is the power output of the energy storage device at the i-th node at time t, P Bj,t is the absorbed power of the energy storage device at the jth node at time t, η B is the efficiency of the energy storage device, is the state of charge of the energy storage device that generates power at the i-th node at time t, is the state of charge of the energy storage device absorbing power at the jth node at time t, is the rated capacity of the energy storage device.

[0023] Furthermore, the voltage waveform distortion influencing factor is:

[0024]

[0025] Where U 1 is the fundamental voltage in the distribution network, U n is the high-order harmonic voltage in the distribution network, n is the harmonic order, V f is the voltage amplitude, is the per-unit output power of the power generation equipment, W sc is the output power of the power generation equipment, W s ' c is the output power reference value of the power generation equipment, V i Indicates the voltage value of the node under normal conditions;

[0026] The overvoltage impact factor is:

[0027]

[0028] In the formula, α 1 and β 1 are weight coefficients, and α 1 +β 1=1; M represents the total number of nodes in the distribution network; μ Δe is the voltage deviation membership of node i, O is the satisfaction coefficient;

[0029] The undervoltage influencing factor is:

[0030]

[0031] In the formula, α 2 and β 2 are weight coefficients, and α 2 +β 2 =1.

[0032] Furthermore, the constraint condition of the adjustable limit of the energy storage device is:

[0033]

[0034] In the formula, is the electric power output by the energy storage device at time t, are the remaining capacity of the energy storage device at time t and time t+1 respectively, are the charging and discharging efficiency of the energy storage device, are the upper and lower limits of the energy storage device’s capacity, and They are the upper and lower limits of the charging and discharging power of the energy storage device respectively.

[0035] Furthermore, the power quality control influencing factor of the distribution network is:

[0036]

[0037] When P need When <1, the energy storage device charging and discharging state will not be changed;

[0038] When 1≤P need When <10, if the node voltage value of the distribution network increases, the energy storage device is charged; if the node voltage value of the distribution network decreases, the energy storage device is discharged;

[0039] When 10≤P need When the energy storage device is charged, it is controlled to discharge first.

[0040] Furthermore, the energy storage device is battery energy storage, and the power generation equipment is renewable energy power generation equipment.

[0041] The technical solution adopted by the present invention is: a power quality control system for a distribution network based on an adjustable limit of energy storage, comprising a collection unit, a calculation unit and a control unit connected in sequence,

[0042] The acquisition unit is used to acquire parameters of the power distribution network;

[0043] The calculation unit is used to calculate the maximum power limit that can be adjusted by the energy storage device according to the parameters of the distribution network under the constraint of the energy storage output limit of the energy storage device of the distribution network; calculate the voltage waveform distortion influence factor, overvoltage influence factor and undervoltage influence factor of the distribution network according to the parameters of the distribution network under the constraint of the output power limit of the power generation equipment of the distribution network and the interval range of the distribution network node voltage; and then calculate the power quality control influence factor of the distribution network according to the parameters of the distribution network, the maximum power limit that can be adjusted by the energy storage device, the voltage waveform distortion influence factor, the overvoltage influence factor and the undervoltage influence factor under the constraint of the adjustable limit of the energy storage device;

[0044] The control unit is used to control the energy storage device according to the calculation result of the power quality control influencing factor of the distribution network.

[0045] The technical solution adopted by the present invention is also: a computer-readable storage medium, including a program, and the program can be executed by a processor to implement the distribution network power quality control method based on the adjustable limit of energy storage.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] 1. In order to enhance the voltage stability of the distribution network under the condition of fluctuations in renewable energy power generation, the present invention effectively controls the power quality of the distribution network by controlling the working mode of the energy storage device based on the adjustable limit of the energy storage device, thereby solving the harmonic problem and reactive power shortage problem of the distribution network.

[0048] 2. The present invention takes the power transmission limit of the distribution network line and the distribution network node voltage as constraints, calculates the voltage waveform distortion influencing factor, overvoltage influencing factor and undervoltage influencing factor of the distribution network, so as to analyze the influencing factors of the waveform distortion (harmonics), overvoltage and undervoltage of the distribution network.

[0049] 3. Under the constraint of the adjustable limit of the energy storage device, the present invention calculates the power quality control influencing factor of the distribution network according to the maximum power limit that the energy storage device can adjust, the voltage waveform distortion influencing factor, etc., and finally determines the working mode of the energy storage device. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 is a flow chart of a method according to an embodiment of the present invention;

[0051] Figure 2 Schematic diagram of the structure of the system according to the embodiment of the present invention.

[0052] In the figure: 1-acquisition unit, 2-computation unit, 3-control unit. DETAILED DESCRIPTION

[0053] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0054] The embodiment of the present invention provides a method for controlling power quality of a distribution network based on adjustable energy storage limits, such as Figure 1 As shown, it includes the following steps:

[0055] Step 1: Collect the parameters of the distribution network; the parameters of the distribution network include the number of transmission lines in the distribution network, the transmission power of the transmission lines in the distribution network, the total number of nodes in the distribution network, the efficiency of the energy storage device, the power output and the power absorption of the energy storage device at each node at time t, the state of charge of the energy storage device that outputs power at each node at time t, the state of charge of the energy storage device that absorbs power at each node at time t, the rated capacity of the energy storage device, the voltage value of the node under normal conditions, the remaining capacity of the energy storage device at time t, the remaining capacity of the energy storage device at time t+1, the fundamental voltage in the distribution network, the high-order harmonic voltage in the distribution network, the harmonic order, the voltage amplitude, the output power of the power generation equipment, the reference value of the output power of the power generation equipment, the voltage deviation membership, the satisfaction coefficient and the weight coefficient α 1 , β 1 , α 2 and β 2 The value of .

[0056] Step 2: Under the constraint condition of the energy storage output limit of the energy storage device of the distribution network, the maximum power limit that can be adjusted by the energy storage device is calculated according to the parameters of the distribution network.

[0057] The constraint condition of the energy storage output limit of the energy storage device of the distribution network is that the energy storage output limit of the energy storage device does not exceed the power transmission limit of the distribution network line. The power transmission limit of the distribution network line is:

[0058]

[0059] Where P x is the transmission power of the xth transmission line in the distribution network.

[0060] The maximum power limit that the energy storage device can adjust is:

[0061]

[0062] Where P Bi,t is the power output of the energy storage device at the i-th node at time t, P Bj,t is the absorbed power of the energy storage device at the jth node at time t, ηB is the efficiency of the energy storage device, is the state of charge of the energy storage device that generates power at the i-th node at time t, is the state of charge of the energy storage device absorbing power at the jth node at time t, is the rated capacity of the energy storage device.

[0063] Step 3: Under the constraints of the output power limit of the power generation equipment of the distribution network and the interval range of the distribution network node voltage, the voltage waveform distortion impact factor, overvoltage impact factor and undervoltage impact factor of the distribution network are calculated according to the parameters of the distribution network.

[0064] The constraint condition of the output power limit of the power generation equipment of the distribution network is that the energy storage output limit of the power generation equipment does not exceed the power transmission limit of the distribution network line.

[0065] The constraints of the interval range of the distribution network node voltage are:

[0066] V i min ≤V i ≤V i max ,i∈M

[0067] Where V i , V i min , V i max They represent the voltage value of the node under normal conditions and its minimum and maximum allowed voltage respectively; i represents the i-th node, and M represents the total number of nodes in the distribution network.

[0068] The voltage waveform distortion influencing factor is:

[0069]

[0070] Where U 1 is the fundamental voltage in the distribution network, U n is the high-order harmonic voltage in the distribution network, n is the harmonic order, V f is the voltage amplitude, is the per-unit output power of the power generation equipment, W sc is the output power of the power generation equipment, W s ' c is the power output reference value of the power generation equipment, V i Indicates the voltage value of the node under normal conditions.

[0071] The overvoltage impact factor is:

[0072]

[0073] In the formula, α 1 and β 1 are weight coefficients, and α 1 +β 1 =1; M represents the total number of nodes in the distribution network; μ Δe is the voltage deviation membership of node i, and O is the satisfaction coefficient.

[0074] The undervoltage influencing factor is:

[0075]

[0076] In the formula, α 2 and β 2 are weight coefficients, and α 2 +β 2 =1.

[0077] Step 4: Under the constraint of the adjustable limit of the energy storage device, calculate the distribution network power quality control influence factor according to the parameters of the distribution network, the maximum power limit that the energy storage device can adjust, the voltage waveform distortion influence factor, the overvoltage influence factor and the undervoltage influence factor. According to the calculation result of the distribution network power quality control influence factor, control the energy storage device. The energy storage device is battery energy storage, and the power generation equipment is renewable energy power generation equipment, including wind power, photovoltaic and other power generation equipment.

[0078] The constraints of the adjustable limit of the energy storage device are:

[0079]

[0080] In the formula, is the electric power output by the energy storage device at time t. A positive value represents discharge, and a negative value represents charging. are the remaining capacity of the energy storage device at time t and time t+1 respectively, are the charging and discharging efficiency of the energy storage device, are the upper and lower limits of the energy storage device’s capacity, and They are the upper and lower limits of the charging and discharging power of the energy storage device respectively.

[0081] Furthermore, the power quality control influencing factor of the distribution network is:

[0082]

[0083] When P need When <1, the current distribution network is in a stable operating state, and the energy storage device charging and discharging state does not change;

[0084] When 1≤Pneed When <10, it means that there is a certain voltage fluctuation in the current distribution network, and it is necessary to control the charging and discharging state of the energy storage device to maintain the stability of the distribution network voltage. If the node voltage value of the distribution network increases, the energy storage device is charged. If the node voltage value of the distribution network decreases, the energy storage device is discharged to maintain the voltage stability of the distribution network. The sensor at the node where the energy storage device is located measures the real-time state of the node voltage value of the node: increase or decrease;

[0085] When 10≤P need When , it indicates that the harmonic content in the distribution network is high, and it is necessary to reduce the harmonic content in the distribution network through voltage quality control. Harmonics are eliminated by using an energy storage device, and the energy storage device is controlled to charge first and then discharge, and the charging and discharging power of the energy storage device meets the constraint conditions.

[0086] In this embodiment, on the basis of satisfying the constraint conditions, it is assumed that there are 50 transmission lines in a distribution network, P z =5000kW, U n =10kV, U 1 =1kV, O=0.86, V i =9.6kV, W sc The output power of the power generation equipment is 1000kW, W s ' c The output power reference value of the power generation equipment is 100kW, the maximum voltage amplitude reference value is 10.6kW, the minimum voltage amplitude reference value is 9.4kW, μ Δe 10% The total number of nodes in the distribution network is 108 nodes, the maximum allowed voltage amplitude is 1.1~1.2 (unit value), the minimum allowed voltage amplitude is 0.8~0.9 (unit value), and the efficiency of the energy storage device is η B =94%, rated capacity of energy storage device At time t, the power output of the energy storage device at the i-th node is 10kW, the power absorbed by the energy storage device at the j-th node is 12kW, the state of charge of the energy storage device that outputs power at the i-th node at time t is 40%, and the state of charge of the energy storage device that absorbs power at the j-th node at time t is 65%. The voltage amplitude V f =380V, α 1 =0.65, β 1 =0.35,α 2 =0.55, β 2 =0.45.

[0087] Under the constraints, the voltage waveform distortion influence factor, overvoltage influence factor and undervoltage influence factor are calculated respectively:

[0088]

[0089]

[0090]

[0091] Under the constraint conditions, the influencing factors of power quality control in the distribution network are calculated:

[0092]

[0093] 1≤5.11<10, indicating that there is a certain voltage fluctuation in the current distribution network, and it is necessary to control the charging and discharging state of the energy storage device to maintain the stability of the distribution network voltage.

[0094] The embodiment of the present invention also provides a power quality control system for a distribution network based on an adjustable limit of energy storage, such as Figure 2 As shown, it includes a collection unit 1, a calculation unit 2 and a control unit 3 connected in sequence.

[0095] The collection unit 1 is used to collect parameters of the distribution network;

[0096] The calculation unit 2 is used to calculate the maximum power limit that can be adjusted by the energy storage device according to the parameters of the distribution network under the constraint of the energy storage output limit of the energy storage device of the distribution network; calculate the voltage waveform distortion influence factor, overvoltage influence factor and undervoltage influence factor of the distribution network according to the parameters of the distribution network under the constraint of the output power limit of the power generation equipment of the distribution network and the interval range of the distribution network node voltage; and then calculate the power quality control influence factor of the distribution network according to the parameters of the distribution network, the maximum power limit that can be adjusted by the energy storage device, the voltage waveform distortion influence factor, the overvoltage influence factor and the undervoltage influence factor under the constraint of the adjustable limit of the energy storage device;

[0097] The control unit 3 is used to control the energy storage device according to the calculation result of the power quality control influencing factor of the distribution network.

[0098] When the system is working, the acquisition unit 1 acquires the parameters of the distribution network, and then transmits the parameters to the calculation unit 2. The parameters of the distribution network include the number of transmission lines in the distribution network, the transmission power of the transmission lines in the distribution network, the total number of nodes in the distribution network, the efficiency of the energy storage device, the power output and power absorption of the energy storage device at each node at time t, the state of charge of the energy storage device that outputs power at each node at time t, the state of charge of the energy storage device that absorbs power at each node at time t, the rated capacity of the energy storage device, the voltage value of the node under normal conditions, the remaining capacity of the energy storage device at time t, the remaining capacity of the energy storage device at time t+1, the fundamental voltage in the distribution network, the high-order harmonic voltage in the distribution network, the harmonic order, the voltage amplitude, the output power of the power generation equipment, the reference value of the output power of the power generation equipment, the voltage deviation membership, the satisfaction coefficient and the weight coefficient α 1 , β 1 , α 2 and β 2 The value of .

[0099] The calculation unit 2 first calculates each constraint condition, and then calculates the maximum power limit that can be adjusted by the energy storage device, the voltage waveform distortion influence factor, the overvoltage influence factor and the undervoltage influence factor according to the parameters of the distribution network under the constraint condition, and finally calculates the distribution network power quality control influence factor according to the parameters of the distribution network, the maximum power limit that can be adjusted by the energy storage device, the voltage waveform distortion influence factor, the overvoltage influence factor and the undervoltage influence factor, and then transmits the calculation result of the distribution network power quality control influence factor to the control unit 3.

[0100] The constraints are:

[0101] (1) The constraint condition of the energy storage output limit of the energy storage device of the distribution network is that the energy storage output limit of the energy storage device does not exceed the power transmission limit of the distribution network line.

[0102] The constraint condition of the output power limit of the power generation equipment of the distribution network is that the energy storage output limit of the power generation equipment does not exceed the power transmission limit of the distribution network line.

[0103] The power transmission limit of the distribution network line is:

[0104]

[0105] Where P x is the transmission power of the xth transmission line in the distribution network.

[0106] (2) The constraints of the voltage range of the distribution network nodes are:

[0107] V i min ≤V i ≤Vi max ,i∈M

[0108] Where V i , V i min , V i max They represent the voltage value of the node under normal conditions and its minimum and maximum allowed voltage respectively; i represents the i-th node, and M represents the total number of nodes in the distribution network.

[0109] (3) The constraint conditions of the adjustable limit of the energy storage device are:

[0110]

[0111] In the formula, is the electric power output by the energy storage device at time t. A positive value represents discharge, and a negative value represents charging. are the remaining capacity of the energy storage device at time t and time t+1 respectively, are the charging and discharging efficiency of the energy storage device, are the upper and lower limits of the energy storage device’s capacity, and They are the upper and lower limits of the charging and discharging power of the energy storage device respectively.

[0112] The parameters that the calculation unit 2 needs to calculate are:

[0113] (1) The maximum power limit that the energy storage device can adjust is:

[0114]

[0115] Where P Bi,t is the power output of the energy storage device at the i-th node at time t, P Bj,t is the absorbed power of the energy storage device at the jth node at time t, η B is the efficiency of the energy storage device, is the state of charge of the energy storage device that generates power at the i-th node at time t, is the state of charge of the energy storage device absorbing power at the jth node at time t, is the rated capacity of the energy storage device.

[0116] (2) The voltage waveform distortion influencing factor is:

[0117]

[0118] Where U 1 is the fundamental voltage in the distribution network, U nis the high-order harmonic voltage in the distribution network, n is the harmonic order, V f is the voltage amplitude, is the per-unit output power of the power generation equipment, W sc is the output power of the power generation equipment, W s ' c is the output power reference value of the power generation equipment, V i Indicates the voltage value of the node under normal conditions.

[0119] (3) The overvoltage impact factor is:

[0120]

[0121] In the formula, α 1 and β 1 are weight coefficients, and α 1 +β 1 =1; M represents the total number of nodes in the distribution network; μ Δe is the voltage deviation membership of node i, and O is the satisfaction coefficient.

[0122] (4) The undervoltage influencing factor is:

[0123]

[0124] In the formula, α 2 and β 2 are weight coefficients, and α 2 +β 2 =1.

[0125] (5) The influencing factors of power quality control in the distribution network are:

[0126]

[0127] The control unit 3 controls the energy storage device in different ways according to the calculation results of the power quality control influencing factors of the distribution network. Specifically:

[0128] When P need When <1, the current distribution network is in a stable operating state, and the energy storage device charging and discharging state does not change;

[0129] When 1≤P need When it is less than 10, it indicates that there is a certain voltage fluctuation in the current distribution network, and it is necessary to control the charging and discharging state of the energy storage device to maintain the stability of the distribution network voltage. If the node voltage value of the distribution network increases, the energy storage device is charged; if the node voltage value of the distribution network decreases, the energy storage device is discharged to maintain the voltage stability of the distribution network.

[0130] When 10≤Pneed When , it indicates that the harmonic content in the distribution network is high, and it is necessary to reduce the harmonic content in the distribution network through voltage quality control. Harmonics are eliminated by using energy storage devices, and the energy storage devices are controlled to charge first and then discharge. The charging and discharging power of the energy storage devices must meet the constraints.

[0131] An embodiment of the present invention further provides a computer-readable storage medium, comprising a program, wherein the program can be executed by a processor to implement the power quality control method of a distribution network based on an adjustable limit of energy storage.

[0132] The present invention has been described in detail above through embodiments, but the contents described are only exemplary embodiments of the present invention and cannot be considered to limit the scope of implementation of the present invention. The protection scope of the present invention is defined by the claims. Anyone who utilizes the technical solution described in the present invention, or a technician in the field, inspired by the technical solution of the present invention, designs a similar technical solution within the essence and protection scope of the present invention to achieve the above technical effects, or makes equal changes and improvements to the scope of application, etc., shall still fall within the scope of protection covered by the patent of the present invention.

Claims

1. A power quality control method for a distribution network based on an adjustable limit of energy storage, characterized in that: The following steps are involved: Collect parameters of distribution network; Under the constraint condition of the energy storage output limit of the energy storage device of the distribution network, calculating the maximum power limit that can be adjusted by the energy storage device according to the parameters of the distribution network; Under the constraints of the output power limit of the power generation equipment of the distribution network and the interval range of the distribution network node voltage, the voltage waveform distortion influence factor, the overvoltage influence factor and the undervoltage influence factor of the distribution network are calculated according to the parameters of the distribution network; Under the constraint of the adjustable limit of the energy storage device, the power quality control influence factor of the distribution network is calculated according to the parameters of the distribution network, the maximum power limit that the energy storage device can adjust, the voltage waveform distortion influence factor, the overvoltage influence factor and the undervoltage influence factor; The energy storage device is controlled according to the calculation result of the power quality control influencing factor of the distribution network.

2. The power quality control method for distribution network based on adjustable limit of energy storage according to claim 1, characterized in that: The parameters of the distribution network include the number of transmission lines in the distribution network, the transmission power of the transmission lines in the distribution network, the total number of nodes in the distribution network, the efficiency of the energy storage device, the power emitted and absorbed by the energy storage device at each node at time t, the charge state of the energy storage device emitting power at each node at time t, the charge state of the energy storage device absorbing power at each node at time t, the rated capacity of the energy storage device, the voltage value of the node under normal conditions, the remaining capacity of the energy storage device at time t, the remaining capacity of the energy storage device at time t+1, the fundamental voltage in the distribution network, the higher harmonic voltage in the distribution network, the harmonic order, the voltage amplitude, the output power of the power generation equipment, the reference value of the output power of the power generation equipment, the voltage deviation membership, the satisfaction coefficient, and the values ​​of the weight coefficients α1, β1, α2 and β2.

3. The power quality control method for distribution network based on adjustable limit of energy storage according to claim 1, characterized in that: The constraint condition of the energy storage output limit of the energy storage device of the distribution network is that the energy storage output limit of the energy storage device does not exceed the power transmission limit of the distribution network line. The constraint condition of the output power limit of the power generation equipment of the distribution network is that the energy storage output limit of the power generation equipment does not exceed the power transmission limit of the distribution network line. The power transmission limit of the distribution network line is: Where P x is the transmission power of the xth transmission line of the distribution network; The constraints of the interval range of the distribution network node voltage are: In i min ≤V i ≤V i max ,i∈M Where V i , V i min , V i max They represent the voltage value of the node under normal conditions and its minimum and maximum allowed voltage respectively; i represents the i-th node, and M represents the total number of nodes in the distribution network.

4. The power quality control method for distribution network based on adjustable limit of energy storage according to any one of claims 1 to 3, characterized in that: The maximum power limit that the energy storage device can adjust is: Where P Bi,t is the power output of the energy storage device at the i-th node at time t, P Bj,t is the absorbed power of the energy storage device at the jth node at time t, η B is the efficiency of the energy storage device, is the state of charge of the energy storage device that generates power at the i-th node at time t, is the state of charge of the energy storage device absorbing power at the jth node at time t, is the rated capacity of the energy storage device.

5. The power quality control method for distribution network based on adjustable limit of energy storage as claimed in claim 4, characterized in that: The voltage waveform distortion influencing factor is: Where U1 is the fundamental voltage in the distribution network, U n is the high-order harmonic voltage in the distribution network, n is the harmonic order, V f is the voltage amplitude, is the per-unit output power of the power generation equipment, W sc is the output power of the power generation equipment, W′ sc is the output power reference value of the power generation equipment, V i Indicates the voltage value of the node under normal conditions; The overvoltage impact factor is: Where α1 and β1 are weight coefficients, and α1+β1=1; M represents the total number of nodes in the distribution network; μ Δe is the voltage deviation membership of node i, O is the satisfaction coefficient; The undervoltage influencing factor is: In the formula, α2 and β2 are both weight coefficients, and α2+β2=1.

6. The power quality control method for distribution network based on adjustable limit of energy storage as claimed in claim 5, characterized in that: The constraints of the adjustable limit of the energy storage device are: In the formula, is the electric power output by the energy storage device at time t, are the remaining capacity of the energy storage device at time t and time t+1 respectively, are the charging and discharging efficiency of the energy storage device, are the upper and lower limits of the energy storage device’s capacity, and They are the upper and lower limits of the charging and discharging power of the energy storage device respectively.

7. The power quality control method for distribution network based on adjustable limit of energy storage according to claim 6, characterized in that: The influencing factors of power quality control in the distribution network are: When P need When <1, the energy storage device charging and discharging state will not be changed; When 1≤P need When <10, if the node voltage value of the distribution network increases, the energy storage device is charged; if the node voltage value of the distribution network decreases, the energy storage device is discharged; When 10≤P need When the energy storage device is charged, it is controlled to discharge first.

8. The power quality control method for distribution network based on adjustable limit of energy storage according to claim 1, characterized in that: The energy storage device is battery energy storage, and the power generation equipment is renewable energy power generation equipment.

9. A power quality control system for a distribution network based on adjustable limits of energy storage, characterized in that: It includes a collection unit, a calculation unit and a control unit connected in sequence, The acquisition unit is used to acquire parameters of the power distribution network; The calculation unit is used to calculate the maximum power limit that can be adjusted by the energy storage device according to the parameters of the distribution network under the constraint condition of the energy storage output limit of the energy storage device of the distribution network; Under the constraints of the output power limit of the power generation equipment of the distribution network and the interval range of the distribution network node voltage, the voltage waveform distortion influence factor, the overvoltage influence factor and the undervoltage influence factor of the distribution network are calculated according to the parameters of the distribution network; Then, under the constraint of the adjustable limit of the energy storage device, the power quality control influence factor of the distribution network is calculated according to the parameters of the distribution network, the maximum power limit that the energy storage device can adjust, the voltage waveform distortion influence factor, the overvoltage influence factor and the undervoltage influence factor; The control unit is used to control the energy storage device according to the calculation result of the power quality control influencing factor of the distribution network.

10. A computer-readable storage medium, comprising a program, wherein the program can be executed by a processor to implement the power quality control method for a distribution network based on an adjustable limit of energy storage as claimed in any one of claims 1 to 8.

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