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CN109787244B - A method to determine the total amount of low-voltage acceleration load shedding in distribution network - Google Patents

A method to determine the total amount of low-voltage acceleration load shedding in distribution network Download PDF

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CN109787244B
CN109787244B CN201910205517.7A CN201910205517A CN109787244B CN 109787244 B CN109787244 B CN 109787244B CN 201910205517 A CN201910205517 A CN 201910205517A CN 109787244 B CN109787244 B CN 109787244B
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load shedding
node
motor
load
voltage
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CN109787244A (en
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林莉
贾源琦
杨仕燕
罗皓
汪莎莎
金鑫
朱丽云
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Chongqing University
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/30—Systems integrating technologies related to power network operation and communication or information technologies for improving the carbon footprint of the management of residential or tertiary loads, i.e. smart grids as climate change mitigation technology in the buildings sector, including also the last stages of power distribution and the control, monitoring or operating management systems at local level
    • Y02B70/3225—Demand response systems, e.g. load shedding, peak shaving
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
    • Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
    • Y04S20/00—Management or operation of end-user stationary applications or the last stages of power distribution; Controlling, monitoring or operating thereof
    • Y04S20/20—End-user application control systems
    • Y04S20/222—Demand response systems, e.g. load shedding, peak shaving

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Abstract

本发明属于电力系统运行和控制技术领域的一种确定配电网低压加速减载总量的方法，将现有低压减载中的基本轮的基础上，引入从节点电压进入减载动作电压门阀值至减载动作之间的电压下降速率作为本发明的减载加速的判据，判断是否实施减载加速，及加速减载轮数，并准确计算各减载轮次的减载量，实现了以最小减载量，快速恢复电压值，保障电力系统的安全稳定运行。

Figure 201910205517

The invention belongs to the technical field of power system operation and control, and belongs to a method for determining the total amount of low-voltage acceleration and load-shedding in a distribution network. On the basis of the existing basic wheel in low-voltage load-shedding, a gate valve from node voltage to load-shedding action voltage is introduced. The voltage drop rate between the value and the load shedding action is used as the criterion for the load shedding acceleration of the present invention, to judge whether to implement the load shedding acceleration, and to accelerate the number of load shedding rounds, and accurately calculate the load shedding amount of each load shedding round to achieve In order to quickly restore the voltage value with the minimum load shedding amount, to ensure the safe and stable operation of the power system.

Figure 201910205517

Description

Method for determining total low-voltage accelerated load shedding amount of power distribution network
Technical Field
The invention relates to the technical field of operation and control of power systems, in particular to a method for determining low-voltage acceleration load shedding total amount of a power distribution network.
Background
The low-voltage load reduction is the most basic and effective measure for emergency voltage control and ensuring the stable operation of the voltage of a power grid, is an important component of a third defense line for the safety and stability of a power system, and is the most direct and effective control means for preventing the voltage breakdown of the system. At present, a widely used low-voltage load shedding scheme is to perform multiple rounds of load shedding, that is, multiple rounds of load shedding are performed when the voltage is lower than a preset voltage threshold and meets the requirement of an extended time. The number of the general load shedding wheels is 2-5, and each round does not skip the step action, namely the load shedding of the basic wheel is generally called; when the power distribution network suffers large voltage disturbance, the node voltage is reduced rapidly and has long duration, and if the condition is still subjected to basic wheel load reduction, the node voltage cannot be recovered rapidly, and the effect of low-voltage load reduction cannot be fully exerted.
Therefore, there is a need for a low voltage load shedding method that can quickly capture and respond quickly when the node voltage in the power distribution network drops quickly.
Disclosure of Invention
In view of the above, the present invention provides a method for determining a total amount of low-voltage accelerated load shedding of a power distribution network, which introduces an acceleration criterion in a basic round, that is, establishes an acceleration criterion for determining whether acceleration load shedding is required or not in a basic round load shedding process, is used for determining whether acceleration load shedding is required or not, and can accurately calculate a load shedding amount.
The invention provides a method for determining the total low-voltage accelerated load shedding amount of a power distribution network, which is characterized by comprising the following steps of: the method comprises the following steps:
s1: determining the load reduction amount of each load reduction round according to the preset total number of the load reduction rounds;
s2: collecting a node voltage value in a power distribution network, comparing the node voltage value with a preset deloading action voltage gate threshold value, continuously collecting the node voltage value of the power distribution network when the node voltage value is greater than the voltage gate threshold value, and calculating a voltage acceleration criterion U when the node voltage is not greater than the voltage gate threshold valuevWherein the voltage acceleration criterion UvThe following method is adopted for calculation,
Figure GDA0002981280350000021
where i ∈ {1,2, …, N }, where N denotes the total number of load shedding rounds, UiRepresents the threshold value of the load shedding motion door of the ith low-voltage load shedding wheel, U represents the node voltage value corresponding to the motion moment of the ith low-voltage load shedding wheel, tiRepresenting the corresponding moment when the voltage value of the node is equal to the voltage threshold value of the ith wheel of load shedding action preset by the node, and t representing the corresponding moment of the ith wheel of low-voltage load shedding action;
s3: when U is turnedvIs less than 0.2Unat/S, no acceleration or load shedding is started, and U isvIs not less than 0.2UnWhen the load is increased or decreased, starting acceleration and load reduction and determining the number of acceleration wheels;
s4: and calculating the total acceleration load shedding amount of the current acceleration load shedding action according to the number of the acceleration wheels and the load shedding amount of each load shedding wheel.
Further, the number of the acceleration wheels is determined by the following method;
when 0.2Un/S≤UV＜Ki+1When the ith wheel is taken as a starting wheel,1-wheel acceleration, namely the number of the wheels is 2, namely the load reduction amount of the ith wheel and the load reduction amount of the (i + 1) th wheel are cut off at one time,
when K isi+1≤UV＜0.6UnWhen the load is reduced, the load reduction quantity of the ith wheel, the (i + 1) th wheel and the (i + 2) th wheel is cut off once, the ith wheel is taken as a starting wheel, the (2) th wheel is accelerated, and the speed of the accelerated wheel is 3,
wherein, Ki+1Indicating a voltage acceleration criterion UvThe acceleration setting value of (1).
Further, the voltage acceleration criterion UvAcceleration setting value K ofi+1Has a value range of 0.2UnS to 0.6Unand/S, and the specific value is determined by a time domain simulation method.
Further, the load reduction amount Δ P is calculated by the following method, and the load reduction amount is the sum of the load reduction amounts of the starting wheel and the number of the acceleration wheels corresponding to the number of the rounds;
when the number of the acceleration wheels is 2, the delta P is equal to delta Pi+△Pi+1Wherein, DeltaP is the load reduction amount of the accelerating wheeliFor the reduction of the ith wheel,. DELTA.Pi+1The reduction amount of the (i + 1) th round;
when the number of the acceleration wheels is 3, the delta P is equal to delta Pi+△Pi+1+△Pi+2Wherein, DeltaP is the load reduction amount of the accelerating wheeliFor the reduction of the ith wheel,. DELTA.Pi+1Is the relief of the (i + 1) th wheel,. DELTA.Pi+2The load shedding amount of the (i + 2) th wheel.
Further, the load shedding amount of each load shedding round is calculated by adopting the following method;
s11: calculating the maximum self-starting capacity corresponding to the node motor under different self-starting initial rotating speeds, wherein the maximum self-starting capacity of the node motor is calculated by adopting the following method;
s111: calculating mechanical power P of nodal motorLSaid mechanical power PLCalculating by adopting the following method;
PL＝P(Aω3+Bω2+Cω) (1)
wherein, PLRepresenting the mechanical power of the nodal motor, P representing a predetermined nodal motorA, B and C respectively represent the mechanical torque coefficient of the induction motor, and omega represents the electrical angular speed omega of the node motor rotorrPer unit value of (a), ω ═ ωr/ω0，ω0Is the stator magnetic field electrical angular velocity;
the initial value of omega is the self-starting initial rotating speed of the node motor;
s112: calculating electromagnetic power P of nodal motorMSaid electromagnetic power PMCalculating by adopting the following method;
Figure GDA0002981280350000031
wherein, PMRepresenting the electromagnetic power of the node motor, P representing the predetermined self-starting capacity of the node motor, U representing the node voltage value, RrRepresenting the equivalent resistance, X, of the rotor winding of a nodal motorσThe sum of the leakage reactance of the stator and the rotor windings of the node motor is represented, and S represents the slip ratio of the node motor;
s113: applying the mechanical power PLAnd electromagnetic power PMSubstituting the following equation to calculate the value of slip S of the new node motor;
Figure GDA0002981280350000032
wherein, TJRepresenting the inertia time constant of the nodal motor, S representing the slip of the nodal motor, PLRepresenting mechanical power of the nodal motor, PMRepresenting the electromagnetic power of the nodal motor;
s114: calculating new node motor rotor electric angular velocity omegar1-S, where S represents the slip of the new node motor in step S113;
s115: the new node motor rotor electrical angular velocity omega of the step S114rStep S11, and repeating steps S111, S112, S113 and S114 until PL＝PMThe rotating speed is recovered to be close to the rated rotating speed and the node voltage is in a normal operating state (namely U meets 0.9U)N～1.1UNRange) indicates that the node motor can start normally under the self-starting capacity of the currently given node motor;
s116: keeping the initial self-starting speed omega of the node motor unchanged, continuously increasing the initial value of the self-starting capacity P of the preset node motor, repeating the steps S111 to S115, if the final speed is reduced, even locked-rotor, and cannot be recovered to the vicinity of the rated speed or even causes the node voltage to be unstable, indicating that the node motor cannot be normally started under the self-starting capacity of the currently given node motor, and then the maximum self-starting capacity P of the node motormaxThe value of (b) is a value of the self-starting capacity P of the previous preset node motor which is immediately adjacent to the self-starting capacity P of the preset node motor when the node motor cannot be normally started;
s12: determining the self-starting initial rotating speed of the node motor of each load shedding round according to the set total number of the load shedding rounds;
s13: and calculating the load reduction amount of each load reduction round according to the maximum self-starting capacity corresponding to the self-starting initial rotating speed.
Further, the specific value of the self-starting initial rotating speed of the node motor of each load shedding turn is obtained by adopting a time domain simulation method.
Further, the self-starting initial rotating speed of the node motor of each load shedding round is determined by adopting the following method:
the corresponding maximum self-starting capacity of the node motor self-starting initial rotating speed omega of the first load shedding round is smaller than the load capacity of the node motor before load shedding,
the node motor self-starting initial rotating speed omega of the final load shedding round is 0p.u.,
the node motor self-starting initial rotating speed omega of the second last deloading round is more than 0.5p.u.
Further, the values of the self-starting initial rotating speed of the node motor of each load shedding turn have the following relationship: omega1＞ω2＞…＞ωNWherein, ω is1Nodal motor self-starting initial speed, ω, representing a first load shedding round2Nodal motor self-starting initial speed, ω, representing a second load shedding roundNThe node motor self-starting initial rotation speed of the Nth deloading wheel number is represented, and N represents the total deloading wheel number.
Further, the load shedding amount of each load shedding turn is calculated by adopting the following method,
collecting the load capacity of the node motor, collecting the maximum self-starting capacity corresponding to the self-starting initial rotating speed of the node motor of each load shedding round, calculating the load shedding amount of each load shedding round by adopting the following method,
△P1＝Pnode (C)-P1
△P2＝P1-P2
...
△PN＝PN-1-PN
Wherein, Δ P1The amount of load reduction, Δ P, for the first load reduction round2Is the load shedding amount, DeltaP, of the second load shedding roundNThe amount of deloading for the Nth deloading round, PNode (C)For relieving the motor load capacity of the front node1、P2、…、PN-1、PNRespectively is the initial rotation speed omega of the node motor1、ω2、…、ωN-1And 0, the maximum self-starting capacity corresponding to the maximum self-starting capacity.
The invention has the beneficial effects that: the invention introduces a voltage drop acceleration criterion in the basic round in the existing low-voltage load shedding, namely, the voltage drop rate from the voltage of a node entering the load shedding action to the load shedding action is introduced as the load shedding acceleration criterion of the invention, and whether acceleration is carried out or not is judged in the load shedding process of each round, thereby realizing the purposes of rapidly inhibiting voltage drop and preventing voltage collapse; in addition, when the node voltage is stable, the calculation of the acceleration criterion is not started, the calculation of the acceleration criterion is started only when the node voltage is unstable, and the change condition of the voltage along with the time after the node voltage is unstable is mainly analyzed, so that the method has higher pertinence and greatly reduces the calculated amount compared with the existing acceleration criterion; when the node voltage is seriously unstable, the load shedding speed in the power distribution network is increased, the voltage value is quickly recovered, and the safe and stable operation of the power system is ensured.
Drawings
The invention is further described below with reference to the following figures and examples:
FIG. 1 is a diagram of a power distribution network structure according to the present invention
FIG. 2 is a simplified equivalent circuit diagram of the distribution network of the present invention
FIG. 3 is a flow chart of the present invention
FIG. 4 is a dynamic graph of node 7 voltage and low voltage load shedding for an induction motor load (disturbance 1)
FIG. 5 is a dynamic graph of node 7 voltage and low voltage load shedding for an induction motor load (disturbance 2)
Detailed Description
The invention is further described with reference to the accompanying drawings in which:
the invention provides a method for determining the total low-voltage accelerated load shedding amount of a power distribution network, which is characterized by comprising the following steps of: the method comprises the following steps:
s1: collecting a node voltage value in a power distribution network, comparing the node voltage value with a node preset deloading action voltage gate threshold value, continuously collecting the node voltage value of the power distribution network when the node voltage value is greater than the voltage gate threshold value, and calculating a voltage acceleration criterion U when the node voltage is not greater than the voltage gate threshold valuevWherein the voltage acceleration criterion UvThe following method is adopted for calculation,
Figure GDA0002981280350000061
where i ∈ {1,2, …, N }, where N denotes the total number of load shedding rounds, UiRepresents the threshold value of the load shedding motion door of the ith low-voltage load shedding wheel, U represents the node voltage value corresponding to the motion moment of the ith low-voltage load shedding wheel, tiRepresenting the corresponding moment when the voltage value of the node is equal to the voltage threshold value of the ith wheel of load shedding action preset by the node, and t represents the corresponding moment of the ith wheel of low-voltage load shedding actionTime of day;
s2: when U is turnedvIs less than 0.2Unat/S, no acceleration or load shedding is started, and U isvIs not less than 0.2UnWhen the load is increased or decreased, starting acceleration and load reduction and determining the number of acceleration wheels;
s3: and calculating the total accelerated load shedding amount of the current accelerated load shedding action according to the number of the accelerated wheels and the load shedding amount of each load shedding wheel.
In the present invention, all values are per unit values.
The invention combines a basic wheel and a special wheel in the existing low-voltage load shedding, introduces the voltage reduction rate from the voltage of a node to the threshold value of a voltage gate of the load shedding action to the load shedding action as the criterion of the load shedding acceleration in the load shedding of the basic wheel, and judges whether the acceleration is carried out or not in the load shedding process of each round, thereby realizing the purposes of quickly inhibiting the voltage drop and preventing the voltage collapse; in addition, when the node voltage is stable, the calculation of the acceleration criterion is not started, the calculation of the acceleration criterion is started only when the node voltage is unstable, and the change condition of the voltage along with the time after the node voltage is unstable is mainly analyzed, so that the method has higher pertinence and greatly reduces the calculated amount compared with the existing acceleration criterion; when the node voltage is seriously unstable, the load shedding speed in the power distribution network is increased, the voltage value is quickly recovered, and the safe and stable operation of the power system is ensured.
In this embodiment, the number of acceleration wheels is determined by the following method,
when 0.2Un/S≤UV＜Ki+1When the number of the wheels is 2, namely the load reduction amount of the ith wheel and the load reduction amount of the (i + 1) th wheel are cut off at one time,
when K isi+1≤UV＜0.6UnWhen the load is reduced, the load reduction quantity of the ith wheel, the (i + 1) th wheel and the (i + 2) th wheel is cut off once, the ith wheel is taken as a starting wheel, the (2) th wheel is accelerated, and the speed of the accelerated wheel is 3,
wherein, Ki+1Indicating a voltage acceleration criterion UvThe acceleration setting value of (1).
Since the total number of load shedding rounds is 2-5 rounds, in the latter load shedding rounds,if the current round is the ith round, when the (i + 1) th round or the (i + 2) th round is larger than the fifth round, accelerating unloading directly unloads the subsequent unloading amount at the same time, for example, when the value of the accelerating criterion of the 4 th round is Ki+1≤UV＜0.6UnAnd S, the (i + 2) th wheel is the 6 th wheel, but the total load shedding wheel is 5 wheels, and the subsequent load shedding amount is directly and once reduced, namely the load shedding amounts of the 4 th wheel and the 5 th wheel are simultaneously reduced when the 4 th wheel carries out load shedding action.
According to the technical scheme, the voltage acceleration criterion U is usedvThe threshold value of (2) to judge the acceleration turn has the advantages of simplicity and easy operation. If the ith round has been cut off, acceleration judgment is not made on the ith round, if the acceleration of the first round deloading round is deloaded for one round, namely the first round and the second round are deloaded for one time, when the situation is met, acceleration judgment is not made on the deloading of the second round, and acceleration judgment is directly made on the deloading round of the third round.
In this embodiment, the voltage acceleration criterion UvAcceleration setting value K ofi+1Has a value range of 0.2UnS to 0.6Unand/S, and the specific value is determined by a time domain simulation method. According to the general technical conditions of low-voltage load reduction and low-voltage splitting devices of the power system, the setting value range of the acceleration criterion is as follows: 0.2UN/s～0.6UNS; allowable error of 0.05U or lessNAnd s. Therefore, the setting value K is mainly acceleratedi+1The specific setting should satisfy the following principle: firstly, the acceleration setting value is related to the operation characteristics of the power distribution network, and the acceleration setting value is properly smaller in areas with higher normal operation voltage; if the normal operation voltage is in a lower area, the acceleration setting value is properly increased; secondly, the acceleration setting value is related to the dynamic characteristics of specific loads of the power distribution network, and if a large number of loads sensitive to voltage reduction exist in the load composition, if the load of the induction motor is more, the acceleration setting value is properly smaller; if the load characteristic is not particularly sensitive to voltage reduction, if the constant impedance load is more, the acceleration setting value should be properly increased to prevent excessive load removal; thirdly, the acceleration setting value is also related to a specific low-voltage load shedding configuration scheme, and if the configured load shedding amount is lessIf the delay time is longer, the setting value is properly smaller; if the amount of load shedding is large and the delay time is short, the setting value should be increased appropriately. Therefore, the specific acceleration setting value should be researched aiming at the specific fault causing the voltage collapse by combining the specific practical situation of the power distribution network, and is determined by adopting a time domain simulation method.
In this embodiment, the load reduction amount Δ P is calculated by the method in which the load reduction amount is the sum of the load reduction amounts of the starting wheel and the number of acceleration wheels,
when the number of the acceleration wheels is 2, the delta P is equal to delta Pi+△Pi+1Wherein, DeltaP is the load reduction amount of the accelerating wheeliFor the reduction of the ith wheel,. DELTA.Pi+1The load shedding amount of the (i + 1) th wheel,
when the number of the acceleration wheels is 3, the delta P is equal to delta Pi+△Pi+1+△Pi+2Wherein, DeltaP is the load reduction amount of the accelerating wheeliFor the reduction of the ith wheel,. DELTA.Pi+1Is the relief of the (i + 1) th wheel,. DELTA.Pi+2The load shedding amount of the (i + 2) th wheel.
In the present embodiment, the calculation of the load shedding of each load shedding round adopts the following method,
s11: calculating the maximum self-starting capacity corresponding to the node motor under different self-starting initial rotating speeds,
wherein the maximum self-starting capacity of the node motor is calculated by adopting the following method,
s111: calculating mechanical power P of nodal motorLSaid mechanical power PLThe following method is adopted for calculation,
PL＝P(Aω3+Bω2+Cω) (1)
wherein, PLRepresenting the mechanical power of the node motor, P representing the predetermined self-starting capacity of the node motor, A, B and C representing the mechanical torque coefficient of the induction motor, and ω representing the electrical angular velocity ω of the rotor of the node motorrPer unit value of (a), ω ═ ωr/ω0，ω0Is the electrical angular velocity of the stator magnetic field,
wherein the initial value of omega is the self-starting initial rotating speed of the node motor,
s112: calculating electromagnetic power P of nodal motorMSaid electromagnetic power PMThe following method is adopted for calculation,
Figure GDA0002981280350000091
wherein, PMRepresenting the electromagnetic power of the node motor, P representing the predetermined self-starting capacity of the node motor, U representing the node voltage value, RrRepresenting the equivalent resistance, X, of the rotor winding of a nodal motorσThe sum of the leakage reactance of the stator and the rotor windings of the node motor is represented, S represents the slip ratio of the node motor,
s113: applying the mechanical power PLAnd electromagnetic power PMSubstituting the equation below, calculating the value of slip S of the new node motor,
Figure GDA0002981280350000092
wherein, TJRepresenting the inertia time constant of the nodal motor, S representing the slip of the nodal motor, PLRepresenting mechanical power of the nodal motor, PMRepresenting the electromagnetic power of the nodal motor,
s114: calculating new node motor rotor electric angular velocity omegarWhere S denotes the slip of the new node motor in step S113,
s115: the new node motor rotor electrical angular velocity omega of the step S114rStep S11, and repeating steps S111, S112, S113 and S114 until PL＝PMThe rotating speed is recovered to be close to the rated rotating speed and the node voltage is in a normal operating state (namely U meets 0.9U)N～1.1UNRange) indicates that the node motor can start properly at the current given self-starting capacity of the node motor,
s116: maintaining a self-starting initial speed ω of a nodal motorContinuously increasing the initial value of the self-starting capacity P of the preset node motor without changing, repeating the steps S111 to S115, if the final rotating speed is reduced or even locked-up causes that the node motor cannot be recovered to the vicinity of the rated rotating speed or even causes that the node voltage is unstable, indicating that the node motor cannot be normally started under the self-starting capacity of the currently given node motor, and then the maximum self-starting capacity P of the node motormaxThe value of (b) is a value of the self-starting capacity P of the previous preset node motor which is immediately adjacent to the self-starting capacity P of the preset node motor when the node motor cannot be normally started;
s12: determining the self-starting initial rotating speed of the node motor of each load shedding round according to the set total number of the load shedding rounds;
s13: and calculating the load reduction amount of each load reduction round according to the maximum self-starting capacity corresponding to the self-starting initial rotating speed.
The node motor refers to an induction motor load which is connected to a node in a power distribution network and is put into operation. When the node voltage drops after the power distribution network is disturbed by the voltage of an induction motor which is connected to a node of the power distribution network and is put into operation, a large amount of reactive power shortage occurs in the induction motor, the rotating speed of the induction motor is reduced along with the node voltage or even stops rotating, and when the operating node voltage is recovered, the rotating speed of the induction motor is the initial self-starting rotating speed of the node motor when the induction motor is re-accelerated, namely omega of the electrical angular speed of a rotor of the induction motorrThe initial value of the per unit value is the initial rotation speed of the node motor in self-starting.
The simplified equivalent diagram of the node motor is shown in fig. 2, and the self-starting of the node motor refers to a process that the rotating speed of the induction motor is reduced or even stopped when the voltage of the running node of the motor is reduced, and the node motor is re-accelerated when the voltage of the running node is recovered. In the embodiment, the self-starting initial rotation speed of the node motor is the node motor rotor electrical angular speed omegarThe initial value of the per unit value ω ranges from 0p.u. to 0.9p.u., where the initial node motor self-starting rotational speed is predetermined by those skilled in the art and ranges from 0p.u. to 0.9p.u. Self-induction motorThe starting dynamic process is an electromechanical process in which active power, reactive power, node voltage and rotating speed are coupled with each other to generate a feedback effect: namely, when the induction motor is started automatically, the electromagnetic power and the mechanical power calculated by the initial rotating speed are unbalanced, so that the rotating speed, namely the slip ratio, is changed; the change of slip ratio affects the change of the equivalent impedance of the induction motor, the change of the equivalent impedance of the induction motor causes the current change, the change of the current affects the reactive power absorbed by the induction motor, thereby causing the change of the operating voltage of the induction motor, and simultaneously, the voltage drop between a power supply and a load also changes due to the change of the current, thereby further affecting the operating voltage of the induction motor, and further affecting the electromagnetic power; the variation in slip in turn also affects the variation in mechanical power. Therefore, the maximum self-starting capacity of the node motor under different initial rotating speeds provided by the invention is the maximum self-starting capacity of the induction motor under the stable state in the process of changing the induction motor from the unstable state to the stable state, so that the maximum self-starting capacity of the node motor under different self-starting rotating speeds in the power distribution network can be accurately calculated, and the accurate calculation of the subsequent load reduction amount is facilitated.
The invention considers the induction motor as the main factor of the voltage collapse of the power distribution network, takes the induction motor as a main load shedding object, determines the total number of load shedding rounds according to the requirement of nodes in the power distribution network on the load shedding precision, determines the node motor self-starting initial rotating speed of each load shedding round according to the total number of the load shedding rounds, calculates the load shedding amount of each round according to the maximum self-starting capacity of the node motor corresponding to the node motor self-starting initial rotating speed, considers the load proportion in the nodes of the power distribution network and accurately calculates the load shedding amount of each round according to the self-starting initial rotating speed of the node motor compared with the prior method for determining the load shedding amount by using the percentage of the node load, thereby ensuring the reliable operation of important loads, rapidly recovering the node voltage by the minimum load shedding amount under the requirement of ensuring the node load shedding precision and ensuring the safe and stable operation of the system.
In this embodiment, the specific value of the self-starting initial rotation speed of the node motor of each load shedding turn is obtained by using a time domain simulation method. At present, there are two main methods for analyzing the transient stability of the power system, namely, a time domain simulation method (also called a gradual integration method) and a direct method (also called a transient energy function method). In the embodiment, the self-starting initial rotating speed of the node motor in the transient state to steady state operation of the node motor is analyzed by taking the self-starting initial rotating speed and the given initial self-starting capacity of the node motor as initial values, the maximum self-starting capacity of the node motor in the transient state to steady state operation of the node motor is analyzed, and the self-starting initial rotating speed of the node motor in each load shedding round is determined by a time domain simulation method according to the total number of the load shedding rounds.
In this embodiment, the self-starting initial rotation speed of the node motor of each load shedding turn is determined by the following method:
the corresponding maximum self-starting capacity of the node motor self-starting initial rotating speed omega of the first load shedding round is smaller than the load capacity of the node motor before load shedding,
the node motor self-starting initial rotating speed omega of the final load shedding round is 0p.u.,
the node motor self-starting initial rotating speed omega of the second last deloading round is more than 0.5p.u.
According to experimental data, when the node motor self-starting initial rotating speed is between 0p.u. and 0.5p.u., the variation of the maximum self-starting capacity of the corresponding node motor is not large, the node motor self-starting initial rotating speed at the last load shedding round is 0p.u., and the node motor self-starting initial rotating speed omega at the last load shedding round is greater than 0.5p.u.
In this embodiment, the values of the initial self-starting rotational speeds of the node motors of the respective load shedding rounds have the following relationship: omega1＞ω2＞…＞ωNWherein, ω is1Indicating a first load shedding roundNode motor self-starting initial speed, omega2Nodal motor self-starting initial speed, ω, representing a second load shedding roundNThe node motor self-starting initial rotation speed of the Nth deloading wheel number is represented, and N represents the total deloading wheel number. By the technical scheme, the purpose of quickly determining the self-starting initial rotating speed of the node motor of each load shedding turn is achieved.
In the present embodiment, the load shedding amount of each load shedding turn is calculated by the following method,
collecting the load capacity of the node motor, collecting the maximum self-starting capacity corresponding to the self-starting initial rotating speed of the node motor of each load shedding round, calculating the load shedding amount of each load shedding round by adopting the following method,
△P1＝Pnode (C)-P1
△P2＝P1-P2
...
△PN＝PN-1-PN
Wherein, Δ P1The amount of load reduction, Δ P, for the first load reduction round2Is the load shedding amount, DeltaP, of the second load shedding roundNThe amount of deloading for the Nth deloading round, PNode (C)For relieving the motor load capacity of the front node1、P2、…、PN-1、PNRespectively is the initial rotation speed omega of the node motor1、ω2、…、ωN-1And 0, the maximum self-starting capacity corresponding to the maximum self-starting capacity.
The total number of the load shedding rounds is 2 to 5 rounds, and the basic round of the low-voltage load shedding device arranged in the system proposed in the technical regulation for automatic low-voltage load shedding of the power system can be set to be 2 to 5 rounds.
The technical scheme of calculating the load reduction amount by taking the maximum self-starting capacity of the node motor corresponding to the node motor self-starting initial rotating speed as the self-starting capacity fully considers the load proportion of each load in the node in the power distribution network and the sensitivity degree of each load to node voltage reduction, compared with the conventional load reduction amount calculation which is not distinguished for node loads, the load reduction amount calculation is more accurate, the load condition of the power distribution network can be reflected in real time, the voltage of the system is changed from the minimum load reduction amount to be stable, and the beneficial effect of ensuring the safe and stable operation of the power system is achieved.
According to the technical scheme, the total accelerated load shedding amount of the accelerated load shedding action can be accurately calculated according to the number of the accelerated wheels.
In this embodiment, as shown in fig. 1 of a practical distribution network structure, the capacity of the transformer T1 is 240MVA, the capacity of the transformer T2 is 63MkVA, and the capacity of the transformer T3 is 40 MVA; the parameters of the induction motor are as follows: xm＝3.3pu，Xσ＝0.15pu，Rr＝0.0127pu，TJ5s, a, B, C, 1; the reference volume was 12.5MVA, and a simplified equivalent diagram is shown in FIG. 2. In a rated state, the motor load power of the node 6 is 0.95p.u., and the constant impedance load power is 0.05p.u. (the power factor is 0.75); the motor load power at node 7 is 2p.u., and the constant impedance load power is 0.5p.u. (power factor of 0.75). Setting system disturbance voltage
Figure GDA0002981280350000131
In the case of a fixed node voltage in normal operation, different self-starting initial rotation speeds of the node 7 induction motors in fig. 2 are set to be 0p.u., 0.1p.u., 0.2p.u., 0.3p.u., 0.4p.u., 0.5p.u., 0.6p.u., 0.7p.u., 0.8p.u., 0.85p.u., and 0.9p.u., respectively, and the corresponding maximum self-starting capacities of the node 7 induction motors are calculated in real time to be 0.88p.u., 0.89p.u., 0.9p.u., 0.91p.u., 0.92p.u., 0.94p.u., 1.01p.u., 1.18p.u., 1.56p.u., 1.93p.u., and 2.9p.u.
The low-voltage load reduction device arranged in the system proposed in the technical regulation for automatic low-voltage load reduction of the power system can be basically arranged for 2 to 5 turns. In this embodiment, the total number of load shedding rounds is determined to be 4 according to the requirement of the nodes in the power distribution network on load shedding accuracy, in this embodiment, the maximum self-starting capacity of the node motor corresponding to the self-starting initial rotation speed of the first round is smaller than the load capacity of the node induction motor by analyzing the maximum self-starting capacity of the nodes corresponding to different initial rotation speeds, and the load of the induction motor of the node 7 is 2, so that the maximum self-starting capacity of the node motor, which is smaller than the load capacity of the induction motor of the node before load shedding, of 1.56p.u. and 1.93p.u. can be selected, and in this embodiment, the self-starting initial rotation speed of the first round of the load shedding node motor is selected to be 0.8p.u. by comprehensively considering the requirement of the load shedding accuracy and the voltage recovery speed after load shedding; the self-starting initial rotating speed of the final wheel load shedding node motor is 0p.u. the corresponding maximum self-starting capacity of the node motor is minimum; the self-starting initial rotating speed is 0-0.5 p.u. the corresponding maximum self-starting capacity of the node motor is not changed greatly, and the self-starting initial rotating speed of the second wheel to the last is set to be 0.6 p.u.;
the initial self-starting rotating speed of the first-wheel load-shedding node motor is 0.8p.u., the initial self-starting rotating speed of the second-last wheel is set to be 0.6p.u., according to N-1 times, namely 3 times, of the total number of the load-shedding wheels, the self-starting rotating speeds are uniformly distributed between 0.8p.u. and 0.6p.u., the initial load-shedding rotating speed of the first wheel is 0.8p.u., the initial load-shedding rotating speed of the second wheel is 0.7p.u., the initial load-shedding rotating speed of the third wheel is 0.6p.u., and the initial load-shedding rotating speed of the last wheel is 0p.u.
The decrement amount is respectively 0.44p.u., 0.38p.u., 0.17p.u., 0.13p.u., the action voltage of each round is respectively 0.89p.u., 0.86p.u., 0.83p.u., 0.8p.u., 0.03p.u., the step difference is 0.03p.u., the action time delay is respectively 0.9s, 1.1s, 1.3s and 1.5s, the action voltage and the action time delay of each round are simulated according to a time domain, and an optimal value is selected according to the result of the time domain simulation.
In the example of fig. 4, under the system voltage disturbance 1, the voltage of the node 7 is stable after the conventional load shedding four wheels, and the load shedding amount is 1; the node 7 adopts the acceleration scheme of the invention to accelerate the voltage stabilization after the first, second and third rounds of load shedding, and the load shedding amount is 0.875; the node 7 voltage and the low voltage load shedding dynamic curve of the induction motor load are shown in figure 4. As can be seen from fig. 4, the low-voltage acceleration load shedding method considering the load shedding speed has a higher voltage recovery speed than the conventional load shedding method, and can more effectively and quickly ensure the voltage stability and ensure the safe and stable operation of the system. And the load shedding amount is less, the load shedding amount can be effectively controlled, and the excessive load shedding amount is avoided, so that the reliable operation of important loads is ensured.
FIG. 5 shows that under the system voltage disturbance 2, the node 7 is still unstable after four conventional load shedding, and the load shedding amount is 1; the node 7 adopts the acceleration scheme of the invention to accelerate the voltage stabilization after the first, second and third rounds of load shedding, and the load shedding amount is 0.875; the node 7 voltage and the induction motor load low voltage load shedding dynamic curve are shown in figure 5. As can be seen from fig. 5, the low-voltage acceleration load shedding method considering the load shedding speed can effectively ensure the voltage stability and ensure the safe and stable operation of the system compared with the conventional load shedding method. And the load shedding amount is less, the load shedding amount can be effectively controlled, and the excessive load shedding amount is avoided, so that the reliable operation of important loads is ensured.
Finally, the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all of them should be covered in the claims of the present invention.

Claims (8)

1.一种确定配电网低压加速减载总量的方法，其特征在于：包括以下步骤：1. A method for determining the total amount of low-voltage acceleration load shedding in distribution network, characterized in that: comprising the following steps: S1：根据预先设定的减载轮次总数，确定各减载轮次的减载量，S1: Determine the load reduction amount of each load reduction round according to the preset total number of load reduction rounds, S2：采集配电网中节点电压值，将所述节点电压值与预设的减载动作电压门阈值比较，当所述节点电压值大于所述电压门阈值时，继续采集配电网的节点电压值，当所述节点电压不大于所述电压门阈值时，计算电压加速判据Uv，其中，
Figure FDA0002981280340000011
其中，i∈{1,2,…,N}，其中N表示减载轮次总数，Ui表示低压减载第i轮减载动作门阈值，U表示低压减载第i轮的动作时刻对应的节点电压值，ti表示当节点电压值与节点预设的减载动作第i轮电压门阈值相等时的对应时刻，t表示低压减载第i轮减载动作的对应时刻；S2: Collect the node voltage value in the distribution network, compare the node voltage value with the preset load shedding action voltage threshold value, and continue to collect the node voltage value of the distribution network when the node voltage value is greater than the voltage threshold value voltage value, when the node voltage is not greater than the voltage gate threshold, calculate the voltage acceleration criterion U v , wherein,
Figure FDA0002981280340000011
Among them, i∈{1,2,…,N}, where N represents the total number of rounds of load shedding, U i represents the threshold value of the load shedding action gate of the ith round of low pressure load shedding, and U represents the corresponding action time of the ith round of low pressure load shedding. The node voltage value of , t i represents the corresponding moment when the node voltage value is equal to the i-th round of voltage gate threshold of the node's preset load shedding action, and t represents the corresponding moment of the i-th round of low-voltage load shedding action; S3：当Uv的取值小于0.2Un/S时，不启动加速减载，当Uv的取值不小于0.2Un/S时，启动加速减载并确定加速轮数；S3: When the value of U v is less than 0.2U n /S, the acceleration load shedding is not started; when the value of U v is not less than 0.2U n /S, the acceleration load shedding is started and the number of acceleration rounds is determined; S4：根据所述加速轮数和所述各减载轮次的减载量计算当前加速减载动作的加速减载总量；S4: Calculate the total amount of acceleration and load reduction of the current acceleration and load reduction action according to the number of acceleration rounds and the load reduction amount of each load reduction round; 其中，所述加速轮数采用如下方法确定，Wherein, the number of acceleration rounds is determined by the following method, 当0.2Un/S≤UV＜Ki+1时，以第i轮为起点轮，加速1轮，即加速轮数为2，即将第i轮的减载量和第i+1轮的减载量一次切除，S表示节点电动机的转差率，Un表示电压的标幺值；When 0.2U n /S≤U V <K i+1 , take the i-th wheel as the starting wheel and accelerate one round, that is, the number of acceleration rounds is 2, that is, the load reduction of the i-th wheel and the i+1-th wheel The load shedding amount is removed once, S represents the slip rate of the node motor, and Un represents the per-unit value of the voltage; 当Ki+1≤UV＜0.6Un/S时，以第i轮为起点轮，加速2轮，加速轮速为3，即将第i轮、第i+1轮和第i+2轮的减载量一次切除，S表示节点电动机的转差率，Un表示电压的标幺值；When K i+1 ≤U V <0.6U n /S, take the i-th round as the starting wheel, accelerate 2 rounds, and the acceleration wheel speed is 3, that is, the i-th round, the i+1-th round and the i+2-th round The load shedding amount is removed at one time, S represents the slip rate of the node motor, and Un represents the per-unit value of the voltage; 其中，Ki+1表示电压加速判据Uv的加速整定值。Among them, K i+1 represents the acceleration setting value of the voltage acceleration criterion U v . 2.根据权利要求1所述的一种确定配电网低压加速减载总量的方法，其特征在于：所述电压加速判据Uv的加速整定值Ki+1的取值范围为0.2Un/S至0.6Un/S，具体取值通过时域仿真法确定。2. A method for determining the total amount of low-voltage acceleration and load-shedding in a distribution network according to claim 1, characterized in that: the value range of the acceleration setting value K i+1 of the voltage acceleration criterion U v is 0.2 U n /S to 0.6U n /S, the specific value is determined by time domain simulation method. 3.根据权利要求1所述的一种确定配电网低压加速减载总量的方法，其特征在于：所述减载量△P采用如下方法计算，减载量为起点轮和加速轮数对应的轮次的减载量之和，3. A method for determining the total amount of low-voltage acceleration and load shedding in a distribution network according to claim 1, characterized in that: the load shedding amount ΔP is calculated by the following method, and the load shedding amount is the number of starting wheels and acceleration wheels The sum of the load shedding of the corresponding rounds, 当加速轮数为2时，△P＝△Pi+△Pi+1，其中，△P为加速轮的减载总量，△Pi为第i轮的减载量，△Pi+1为第i+1轮的减载量，When the number of acceleration wheels is 2, △P=△P i +△P i+1 , where △P is the total load reduction of the acceleration wheel, △P i is the load reduction of the i-th wheel, and △P i+ 1 is the load shedding amount of the i+1th round, 当加速轮数为3时，△P＝△Pi+△Pi+1+△Pi+2，其中，△P为加速轮的减载总量，△Pi为第i轮的减载量，△Pi+1为第i+1轮的减载量，△Pi+2为第i+2轮的减载量。When the number of accelerating wheels is 3, △P=△P i +△P i+1 +△P i+2 , where △P is the total load shedding of the accelerating wheels, and △P i is the load shedding of the i-th wheel ΔP i+1 is the load reduction amount of the i+1th round, and ΔP i+2 is the load reduction amount of the i+2th round. 4.根据权利要求1所述的一种确定配电网低压加速减载总量的方法，其特征在于：所述各减载轮次的减载量采用如下方法计算，4. A method for determining the total amount of low-voltage acceleration load shedding in a distribution network according to claim 1, wherein: the load shedding amount of each load shedding round is calculated by the following method: S11：计算节点电动机在不同自启动初始转速下所对应的最大自启动容量，S11: Calculate the maximum self-starting capacity of the node motor at different self-starting initial speeds, 其中，所述节点电动机最大自启动容量采用如下方法计算，Among them, the maximum self-starting capacity of the node motor is calculated by the following method: S111：计算节点电动机的机械功率PL，所述机械功率PL采用如下方法计算，S111: Calculate the mechanical power PL of the node motor, and the mechanical power PL is calculated by the following method: PL＝P(Aω3+Bω2+Cω) (1)P L =P(Aω 3 +Bω 2 +Cω) (1) 其中，PL表示节点电动机的机械功率，P表示预先给定的节点电动机的自启动容量，A、B和C分别表示感应电动机的机械转矩系数，ω表示节点电动机转子电角速度ωr的标幺值，ω＝ωr/ω0，ω0为定子磁场电角速度，Among them, PL represents the mechanical power of the node motor, P represents the preset self-starting capacity of the node motor, A, B and C represent the mechanical torque coefficient of the induction motor respectively, ω represents the standard of the node motor rotor electrical angular velocity ω r Unitary value, ω=ω r /ω 0 , ω 0 is the electric angular velocity of the stator magnetic field, 其中，ω的初始值为所述节点电动机的自启动初始转速，Among them, the initial value of ω is the self-starting initial speed of the node motor, S112：计算节点电动机的电磁功率PM，所述电磁功率PM采用如下方法计算，S112: Calculate the electromagnetic power P M of the node motor, and the electromagnetic power P M is calculated by the following method:
Figure FDA0002981280340000021
Figure FDA0002981280340000021
 其中，PM表示节点电动机的电磁功率，P表示预先给定的节点电动机的自启动容量，U表示节点电压值，Rr表示节点电动机转子绕组的等值电阻，Xσ表示节点电动机定、转子绕组漏抗之和，S表示节点电动机的转差率，Among them, P M represents the electromagnetic power of the node motor, P represents the preset self-starting capacity of the node motor, U represents the node voltage value, R r represents the equivalent resistance of the node motor rotor winding, X σ represents the node motor stator and rotor The sum of winding leakage reactance, S represents the slip of the node motor, S113：将所述机械功率PL和电磁功率PM代入如下式子，计算新的节点电动机的转差率S的值，S113: Substitute the mechanical power P L and the electromagnetic power P M into the following equations to calculate the value of the slip S of the new node motor,
Figure FDA0002981280340000031
Figure FDA0002981280340000031
 其中，TJ表示节点电动机的惯性时间常数,S表示节点电动机的转差率，PL表示节点电动机的机械功率,PM表示节点电动机的电磁功率,Among them, T J represents the inertia time constant of the node motor, S represents the slip rate of the node motor, PL represents the mechanical power of the node motor, P M represents the electromagnetic power of the node motor, S114：计算新的节点电动机转子电角速度ωr的标幺值ω，ω＝1-S，其中，S表示步骤S113中的新的节点电动机的转差率，S114: Calculate the per-unit value ω of the rotor electrical angular velocity ω r of the new node motor, where ω=1-S, where S represents the slip of the new node motor in step S113, S115：将S114步的新的节点电动机转子电角速度ωr的标幺值ω代入步骤S11，重复步骤S111、S112、S113和S114，直至PL＝PM，转速恢复至额定转速附近且节点电压在正常运行状态时表示节点电动机在当前给定的节点电动机的自启动容量下能正常启动，S115: Substitute the per-unit value ω of the new node motor rotor electrical angular velocity ωr in step S114 into step S11, and repeat steps S111, S112, S113 and S114 until P L =P M , the speed returns to the vicinity of the rated speed and the node voltage In the normal operation state, it means that the node motor can start normally under the current given self-starting capacity of the node motor. S116：保持节点电动机的自启动初始转速ω不变，不断增大所述预先给定的节点电动机的自启动容量P的初始值，重复步骤S111至S115，若最终转速下降甚至堵转导致无法恢复至额定转速附近或者甚至导致节点电压失稳，则表示节点电动机在当前给定的节点电动机的自启动容量下不能正常启动，则节点电动机的最大自启动容量Pmax的取值为节点电动机不能正常启动时与所述预先给定的节点电动机的自启动容量P紧邻的前一个所述预先给定的节点电动机的自启动容量P取值；S116: Keep the initial self-starting speed ω of the node motor unchanged, continuously increase the preset initial value of the self-starting capacity P of the node motor, and repeat steps S111 to S115, if the final speed drops or even stalls, it cannot be recovered If it is near the rated speed or even causes the node voltage to become unstable, it means that the node motor cannot start normally under the current given self-starting capacity of the node motor, then the value of the maximum self-starting capacity Pmax of the node motor is that the node motor cannot be normal. The value of the self-starting capacity P of the previous predetermined node motor immediately adjacent to the self-starting capacity P of the predetermined node motor when starting; S12：根据设定的减载轮次总数，确定各减载轮次的节点电动机的自启动初始转速；S12: According to the set total number of load shedding rounds, determine the self-starting initial speed of the node motor of each load shedding round; S13：根据所述自启动初始转速所对应的最大自启动容量，计算各减载轮次的减载量。S13: Calculate the load shedding amount of each load shedding round according to the maximum self-starting capacity corresponding to the initial self-starting rotational speed. 5.根据权利要求4所述的一种确定配电网低压加速减载总量的方法，其特征在于：所述各减载轮次的节点电动机的自启动初始转速的具体值采用时域仿真法获得。5 . The method for determining the total amount of low-voltage acceleration and load shedding in a distribution network according to claim 4 , wherein: the specific value of the self-starting initial speed of the node motor of each load shedding round adopts time domain simulation. 6 . obtained by law. 6.根据权利要求4所述的一种确定配电网低压加速减载总量的方法，其特征在于：所述各减载轮次的节点电动机的自启动初始转速采用如下方法确定：6. A method for determining the total amount of low-voltage acceleration and load shedding in a distribution network according to claim 4, wherein: the self-starting initial rotational speed of the node motor of each load shedding round is determined by the following method: 第一减载轮次的节点电动机自启动初始转速ω的对应的最大自启动容量小于减载前节点电动机负荷容量，The corresponding maximum self-starting capacity of the node motor self-starting initial speed ω in the first load shedding round is less than the load capacity of the node motor before load shedding, 最末减载轮次的节点电动机自启动初始转速ω为0p.u.，The initial speed ω of the motor at the node of the last load shedding round is 0p.u. 倒数第二减载轮次的节点电动机自启动初始转速ω大于0.5p.u.。The initial rotational speed ω of the motor at the node of the penultimate load shedding round is greater than 0.5p.u. 7.根据权利要求4所述的一种确定配电网低压加速减载总量的方法，其特征在于：所述各减载轮次的节点电动机的自启动初始转速的取值存在以下关系：ω1＞ω2＞…＞ωN，其中，ω1表示第一减载轮次的节点电动机自启动初始转速，ω2表示第二减载轮次的节点电动机自启动初始转速，ωN表示第N减载轮次的节点电动机自启动初始转速，N表示总的减载轮次数。7. The method for determining the total amount of low-voltage acceleration and load shedding in a distribution network according to claim 4, wherein: the values of the self-starting initial rotational speeds of the node motors of each load shedding round have the following relationship: ω 1 >ω 2 >...>ω N , where ω 1 represents the initial speed of the node motor self-starting in the first load shedding round, ω 2 represents the initial speed of the node motor self-starting in the second load shedding round, and ω N represents The initial speed of the motor at the node of the Nth load shedding round is self-starting, and N represents the total number of load shedding rounds. 8.根据权利要求4所述的一种确定配电网低压加速减载总量的方法，其特征在于：所述各个减载轮次的减载量采用如下方法计算，8. A method for determining the total amount of low-voltage acceleration and load shedding in a distribution network according to claim 4, wherein the load shedding amount of each load shedding round is calculated by the following method: 采集节点电动机负荷容量，采集所述各减载轮次的节点电动机的自启动初始转速对应的最大自启动容量，计算各减载轮次的减载量，所述各减载轮次的减载量采用如下方法计算，Collect the load capacity of the node motor, collect the maximum self-starting capacity corresponding to the self-starting initial speed of the node motor of each load shedding round, calculate the load shedding amount of each load shedding round, and the load shedding of each load shedding round The amount is calculated as follows: △P1＝P节-P1 △P 1 =P section -P 1 △P2＝P1-P2 ΔP 2 =P 1 -P 2 ...... △PN＝PN-1-PN △P N =P N-1 -P N 其中，△P1为第一减载轮次的减载量，△P2为第二减载轮次的减载量，△PN为第N减载轮次的减载量，P节为减载前节点电动机负荷容量，P1、P2、…、PN-1、PN分别为节点电动机自启动初始转速ω1、ω2、…、ωN-1、0所对应的最大自启动容量。Among them, ΔP 1 is the load shedding amount of the first load shedding round, ΔP 2 is the load shedding amount of the second load shedding round, ΔP N is the load shedding amount of the Nth load shedding round, and Section P is The load capacity of the node motor before load shedding , P 1 , P 2 , . Start capacity.
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