A low-voltage distribution network non-power-off online ice melting method based on a mobile power supply device

Abstract

The present application relates to a kind of low-voltage distribution network without power on-line ice melting method based on mobile power supply equipment, comprising the following steps: obtaining meteorological information, and line parameter information and line icing information of low-voltage distribution network;According to the meteorological information, the line parameter information and the line icing information, the minimum ice-melting current required for icing line is calculated, and the ice-melting line power under the minimum ice-melting current;Select the first mobile power supply equipment for issuing power, or deploy the second mobile power supply equipment with the first mobile power supply equipment respectively for issuing power and absorbing power, to carry out ice melting operation based on the ice-melting line power.The present application can melt ice without power, and improve the support ability of distribution network line to respond to extreme cold weather.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power distribution network online ice melting, in particular to a low-voltage power distribution network non-stop online ice melting method based on a mobile power supply device. BACKGROUND

[0002] The power distribution network is an important part of the power system, and is the link between the high-voltage distribution network and the low-voltage users, and is the key link to ensure reliable and safe power supply. However, in China, the low-temperature rain and snow weather occurs frequently in winter, which causes regional icing of the power distribution line, and in severe cases, it can cause conductor interphase galloping, tower collapse, and aluminum wire fracture, etc. problems, which not only affects the reliability of power supply, but also can cause short circuit, pollution flashover and other power accidents, causing significant economic losses and seriously endangering the safe and stable operation of the power grid. There are more than 30 kinds of ice melting methods at present, which can be roughly divided into three categories: mechanical deicing method, natural deicing method and electric heating deicing method. The electric heating deicing method increases the current density in the conductor to promote the heating of the conductor to achieve ice melting, which has the advantages of simple operation, convenience, fast deicing speed, etc. and can effectively deal with the line icing problem caused by extreme weather such as low temperature and freezing in winter. It is recognized as the most effective ice melting method at home and abroad.

[0003] At present, the electric heating deicing method of transmission and distribution lines mainly includes alternating current deicing and direct current deicing, and according to the different installation methods, the existing alternating / direct current deicing devices mainly include fixed type and mobile type. Various types of alternating / direct current deicing devices have been developed at home and abroad, providing technical means for power grid disaster resistance. However, the above-mentioned ice melting methods are mainly aimed at the main network line, and all need to be short-circuited after the line is shut down, which affects the normal power supply of the power grid during the winter peak period, causing inconvenience and loss to users. The distribution network line is widely distributed, with many branch lines and complex line types, and is located in harsh terrain and climate conditions, and often passes through icing-prone micro-topography and micro-climate areas. For a long time, artificial deicing method has been mainly used, which has low deicing efficiency and high labor intensity, and there are great safety hazards in live ice breaking, making the distribution network line weak in resisting rain and snow disasters, and difficult to ensure the reliability of user power supply. At the same time, it is also a difficult point in ice disaster prevention and control, and the non-stop ice melting of the distribution network line has not been practiced in the power grid.

[0004] Document CN117080975A discloses a power mobile AC ice melting device, which installs an ice melting transformer as an AC power source at the head of an iced line, short-circuits the tail end to achieve the purpose of ice melting, the secondary side of the ice melting transformer is a step-down transformer with multiple taps, and a parallel capacitor bank is used as reactive support to reduce the demand of AC ice melting on the reactive output power of the generator set. This scheme needs to shut down the relevant line during ice melting, which affects the normal power supply of the power grid during the winter peak period, causing inconvenience and loss to users. In addition, the ice melting process requires mutual cooperation of multiple departments of the power grid, complex switching operation, long ice melting preparation time, and high requirements for dispatching operators. Moreover, the ice melting operation requires the purchase of special ice melting power supply equipment, increasing the cost and the cost performance, and it does not have universal promotion conditions. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a low-voltage distribution network non-stop online ice melting method based on mobile power supply equipment, which can melt ice without power failure and improve the support ability of distribution network lines to extreme cold weather.

[0006] The technical solution adopted by the present application to solve the technical problem is to provide a low-voltage distribution network non-stop online ice melting method based on mobile power supply equipment, comprising the following steps:

[0007] Obtain meteorological information, line parameter information and line icing information of the low-voltage distribution network;

[0008] According to the meteorological information, the line parameter information and the line icing information, calculate the minimum ice melting current required by the iced line and the ice melting line power under the minimum ice melting current;

[0009] Select a first mobile power supply equipment for power emission or a second mobile power supply equipment and the first mobile power supply equipment for power emission and power absorption respectively to perform ice melting operation based on the ice melting line power.

[0010] Further, the ice melting line power includes ice melting side active power, line ice melting required active power and line ice melting required reactive power.

[0011] Further, when the first mobile power supply equipment is selected for power emission, the ice melting operation based on the ice melting line power includes:

[0012] Obtain the active load of the front-end line of the first mobile power supply equipment;

[0013] According to the ice melting line active power and the active load of the front-end line of the first mobile power supply equipment, calculate the active power emitted by the first mobile power supply equipment;

[0014] Controlling the first mobile power supply device to send active power for ice melting operation.

[0015] Further, when the first mobile power supply device is selected to send power, it further includes:

[0016] Obtaining the reactive load of the front-end line of the first mobile power supply device, and the active load and reactive load of the back-end line, and calculating the total apparent power of the distribution transformer;

[0017] Obtaining the rated capacity of the distribution transformer, judging whether the total apparent power of the distribution transformer is greater than its rated capacity, and if it is greater than its rated capacity, further deploying a second mobile power supply device and the first mobile power supply device to send and absorb active power respectively.

[0018] Further, the total apparent power of the distribution transformer is represented as

[0019] ,

[0020] ,

[0021] ,

[0022] Wherein, S T is the total apparent power of the distribution transformer, P T is the active power that the distribution transformer needs to send to the upper-level power grid, Q T is the reactive power of the distribution transformer, P R is the active power on the ice melting side, P h is the active load of the back-end line of the first mobile power supply device, P r is the active power required for line ice melting, Q C is the reactive power of the first mobile power supply device, Q r is the reactive power required for line ice melting, Q f and Q h are the reactive loads of the front-end line and back-end line of the first mobile power supply device respectively.

[0023] Further, when the second mobile power supply device is selected to send power and the first mobile power supply device is selected to absorb power, the ice melting operation based on the ice melting line power includes:

[0024] Obtaining the active load of the front-end and back-end lines of the first mobile power supply device;

[0025] set a cooperative strategy, the cooperative strategy is to make the first mobile power supply device emit active power, the second mobile power supply device absorbs active power, or make the second mobile power supply device emit active power, the first mobile power supply device absorbs active power;

[0026] Based on the set cooperative strategy, according to the active power of the ice melting line and the active load of the front and rear lines of the first mobile power supply device, the active power of the first mobile power supply device and the second mobile power supply device is calculated respectively, and then the first mobile power supply device and the second mobile power supply device are controlled to execute the set cooperative strategy to carry out ice melting operation.

[0027] Further, when the first mobile power supply device emits active power and the second mobile power supply device absorbs active power, the active power absorbed by the second mobile power supply device satisfies the following relationship:

[0028] ,

[0029] Wherein, P C2 is the active power absorbed by the second mobile power supply device, P T is the active power required by the distribution transformer to send to the upper grid, P R is the active power on the ice melting side, P h is the active load of the rear line of the first mobile power supply device, P r is the active power required for line ice melting.

[0030] Further, when the first mobile power supply device emits active power and the second mobile power supply device absorbs active power, the active power of the first mobile power supply device, the second mobile power supply device and the distribution transformer satisfies the following relationship:

[0031] ,

[0032] Wherein, Q T is the reactive power of the distribution transformer, Q C is the reactive power of the first mobile power supply device, Q C2 is the reactive power of the second mobile power supply device, Q r is the reactive power required for line ice melting, Q f and Q h are the reactive load of the front and rear lines of the first mobile power supply device respectively.

[0033] Further, when the second mobile power supply device emits active power and the first mobile power supply device absorbs active power, the active power emitted by the second mobile power supply device satisfies the following relationship:

[0034] ,

[0035] wherein P C2 is the active power emitted by the second mobile power supply device, P T is the active power required by the distribution transformer to send back to the upper-level power grid, P R is the active power on the ice-melting side, P h is the active load of the rear-end line of the first mobile power supply device, P r is the active power required for line ice-melting.

[0036] Further, when the second mobile power supply device emits active power and the first mobile power supply device absorbs active power, the reactive power of the second mobile power supply device and the distribution transformer satisfies the following relationship:

[0037] ,

[0038] wherein Q T is the reactive power of the distribution transformer, Q C2 is the reactive power of the second mobile power supply device, Q r is the reactive power required for line ice-melting, Q f and Q h are the reactive loads of the front-end line and the rear-end line of the first mobile power supply device, respectively.

[0039] Further, the first mobile power supply device is deployed at the end of the iced line away from the distribution transformer.

[0040] Further, the second mobile power supply device is deployed at the low-voltage side distribution box of the distribution transformer.

[0041] Further, the minimum ice-melting current is represented as

[0042] ,

[0043] wherein I r is the minimum ice-melting current, Δt is the difference between the ambient temperature and zero degrees Celsius, T r is the selected ice-melting time, g0 is the specific gravity of ice, R T0 is the equivalent ice layer thermal conduction thermal resistance, R T1 is the equivalent convective and radiative thermal resistance, D is the outer diameter of the iced line, and d is the line diameter.

[0044] Further, the active power on the ice-melting side is represented as

[0045] ,

[0046] wherein P R is the ice-melting active power, U is the output line voltage of the first mobile power supply device, I r is the minimum ice-melting current.

[0047] Further, the active power required for the line ice-melting is represented as

[0048] ,

[0049] wherein P r is the active power required for the line ice-melting, I r is the minimum ice-melting current, R0 is the unit length resistance value of the conductor, L r is the line length.

[0050] Advantages

[0051] With the above technical solutions, the present application has the following advantages and positive effects compared with the prior art: the present application calculates the minimum ice-melting current and the ice-melting line power under the current according to the meteorological information, the parameter information and the icing information of the iced line, and selects and deploys the first mobile power supply device to emit power or deploys the second mobile power supply device and the first mobile power supply device to emit power and absorb power, respectively, according to the line power distribution in the transformer area, so as to perform ice-melting operation based on the ice-melting line power, which can effectively solve the problem of iced distribution network line caused by extreme weather such as low temperature and freezing in winter, and greatly improve the support ability of the distribution network line to respond to extremely cold climate; the present application proposes to deploy the first mobile power supply device and the second mobile power supply device to emit power and absorb power, respectively, to cooperatively perform ice-melting operation, which can reduce the active power required to be sent back to the upper power grid by the distribution transformer, and reduce the performance requirement of the mobile power supply device, compared with deploying only the first mobile power supply device to emit power for ice-melting; the online ice-melting scheme provided by the present application does not need to perform short circuit after the line is shut down, which saves the complex switching operation, reduces the ice-melting preparation time and the requirement for dispatching operation personnel, and can also maximize the influence of ice-melting operation on user power consumption, achieve the ice-melting operation with "zero perception" of the user, and can fully utilize the existing emergency power supply and energy storage power supply resources of the current local companies, reduce the demand and dependence on ice-melting devices, and effectively improve the power supply reliability and user power consumption happiness. BRIEF DESCRIPTION OF DRAWINGS

[0052] Figure 1 is the low-voltage distribution network alternating current non-power-off online ice-melting system scheme flowchart of preferred embodiment 1 of the present application;

[0053] Figure 2is a preferred embodiment 1 of the embodiment of the application in the ice melting operation system diagram without power failure when only one power supply vehicle is put in;

[0054] Figure 3 is a preferred embodiment 2 of the embodiment of the application in the ice melting operation system diagram without power failure when two power supply vehicles are put in. DETAILED DESCRIPTION

[0055] The application will be further described below in connection with specific embodiments. It should be understood that these embodiments are only used to illustrate the application and not used to limit the scope of the application. Furthermore, it should be understood that after reading the content of the application, those skilled in the art can make various modifications or changes to the application, and these equivalent forms also fall within the scope of the appended claims of the application.

[0056] The embodiment of the application relates to a low-voltage distribution network non-power failure online ice melting method based on a mobile power supply device, and comprises the following steps:

[0057] Obtaining meteorological information, and line parameter information and line icing information of the low-voltage distribution network;

[0058] According to the above information, the minimum ice melting current required by the icing line and the ice melting line power under the minimum ice melting current are calculated.

[0059] The first mobile power supply device is selected to be deployed to emit power, or the second mobile power supply device is selected to be deployed together with the first mobile power supply device to emit power and absorb power respectively, so as to carry out ice melting operation based on the ice melting line power.

[0060] More specifically, the ice melting line power comprises ice melting side active power, line ice melting required active power and line ice melting required reactive power.

[0061] When the first mobile power supply device is selected to be deployed to emit power to carry out ice melting operation based on the ice melting line power, the following method can be used:

[0062] Obtaining the active load of the front line of the first mobile power supply device;

[0063] According to the ice melting line active power and the active load of the front line of the first mobile power supply device, the active power emitted by the first mobile power supply device is calculated.

[0064] The first mobile power supply device emits active power to carry out ice melting operation.

[0065] When the second mobile power supply device is selected to be deployed together with the first mobile power supply device to emit power and absorb power respectively to carry out ice melting operation based on the ice melting line power, the following method can be used:

[0066] acquire active power load of front and rear lines of the first mobile power supply device;

[0067] set a cooperative strategy, the cooperative strategy is to make the first mobile power supply device emit active power and the second mobile power supply device absorb active power, or make the second mobile power supply device emit active power and the first mobile power supply device absorb active power;

[0068] based on the set cooperative strategy, according to active power of the de-icing line and active power load of the front and rear lines of the first mobile power supply device, active power of the first mobile power supply device and the second mobile power supply device is calculated respectively, and then the first mobile power supply device and the second mobile power supply device are controlled to perform the set cooperative strategy to carry out de-icing operation.

[0069] wherein the second mobile power supply device is deployed at a different position from the first mobile power supply device.

[0070] In specific implementation, the first mobile power supply device and the second mobile power supply device are preferably deployed simultaneously to cooperate to reduce active power that needs to be sent back to the upper power grid by the distribution transformer and simultaneously reduce total apparent power pressure of the distribution transformer. Especially when the rated capacity of the distribution transformer cannot meet the total apparent power pressure thereof, a new mobile power supply device needs to be deployed to absorb active power. The total apparent power of the distribution transformer is represented as

[0071]

[0072]

[0073]

[0074] wherein S T is the total apparent power of the distribution transformer, P T is active power that needs to be sent back to the upper power grid by the distribution transformer, Q T is reactive power of the distribution transformer, P R is active power on the de-icing side, P h is active power load of the rear line of the first mobile power supply device, P r is active power required for line de-icing, Q C is reactive power of the first mobile power supply device, Q r is reactive power required for line de-icing, Q f and Q h are reactive power load of the front and rear lines of the first mobile power supply device respectively.

[0075] One preferred embodiment 1 of the embodiment is based on a low-voltage distribution network alternating current online de-icing system of a mobile power supply device, which comprises:

[0076] ​​​The line icing condition evaluation system has an input side of external sensors and other information input devices for obtaining line icing information and meteorological information, and an output side connected to a mobile power supply device control system, and the preferred mobile power supply device can be a low-voltage power supply vehicle, which transmits ice-melting current and power information to the mobile power supply device control system;

[0077] The ice-melting power supply cooperative control system has an input side of the line icing condition control system and an output side of the controlled mobile power supply device, which is used for cooperative control of the mobile power supply device participating in ice-melting operation according to the ice-melting current and power information;

[0078] The mobile power supply device is preferably a movable power supply vehicle such as an energy storage power supply vehicle or a diesel generator vehicle, which is controlled by the ice-melting power supply cooperative control system and outputs or absorbs power to the icing distribution network area line, and is used for providing ice-melting current to the icing distribution network area line and increasing line heating power to realize ice-melting;

[0079] The line icing information includes distribution area transformer capacity, existing load distribution, line type, line length, conductor resistance value, line outer diameter, ice thickness, and line outer diameter after icing;

[0080] The meteorological information includes ambient temperature and ambient wind speed;

[0081] The ice-melting current and power information includes the minimum ice-melting current required by the icing line, and the active power and reactive power output / absorbed by the ice-melting power supply vehicle;

[0082] The cooperative control information includes the active power output / absorbed by the ice-melting power supply vehicle, the reactive power output / absorbed by the ice-melting power supply vehicle, and the corresponding working time.

[0083] As shown in Figure 1 The low-voltage distribution network alternating current on-line ice-melting system based on the power supply vehicle specifically includes the following steps:

[0084] S1: Obtain line parameter information, line icing condition, and meteorological information.

[0085] S2: Determine the required ice-melting current and ice-melting line power information according to the above information.

[0086] S3: Determine the ice-melting area and line power distribution, mobile power supply arrangement mode and position according to the above power information, and complete the mobile power supply arrangement.

[0087] S4: Access the ice-melting power supply, cooperatively control the active and reactive power output / absorption of the ice-melting power supply, and realize line loading and ice-melting operation.

[0088] In S1, the line parameter information includes distribution area transformer capacity S0, existing load distribution, line type, line length L, conductor unit length resistance value R0, conductor unit length reactance value X0, line diameter d. r

[0089] The line icing condition includes line icing thickness b and line outer diameter D after icing.

[0090] The meteorological information includes ambient temperature t and ambient wind speed f.

[0091] In S2, the ice-melting current and power information includes the minimum ice-melting current required by the iced line, active power consumed by the line under the ice-melting current, and reactive power consumed by the line.

[0092] The required ice-melting current I r is determined according to the provided information.

[0093]

[0094] In the formula, Δt is the difference between the ambient temperature and zero degrees Celsius, T r is the selected ice-melting time, g0 is the specific gravity of ice, which is usually 0.9, R T0 is the equivalent ice layer thermal conduction thermal resistance, which is related to the outer diameter of the conductor and the thickness of the ice layer, R T1 is the equivalent thermal resistance of convection and radiation, which is related to the outer diameter of the conductor, the thickness of the ice layer, and the wind speed.

[0095] The ice-melting line power includes ice-melting side active power P R , active power P r required by the line for ice-melting, and reactive power Q r required by the line for ice-melting.

[0096] In S3, the ice-melting side active power P R emitted by the ice-melting power supply is calculated according to the following formula:

[0097]

[0098] In the formula, U is the output line voltage of the ice-melting power supply, which is usually in the range of 380-400V for low-voltage lines in distribution networks.

[0099] The active power P r required by the line for ice-melting is calculated according to the following formula:

[0100]

[0101] The reactive power Q r required by the line for ice-melting is calculated according to the following formula:

[0102] ​

[0103] Wherein, the power distribution of S3 ice-melting substation and line includes active power and reactive power consumed / output by distribution transformer under ice-melting current, iced line, other lines of substation and ice-melting power supply vehicle. The power distribution of ice-melting substation and line, power supply arrangement mode and position are determined according to the power information.

[0104] The specific steps of completing power supply arrangement are as follows: firstly, the position of one ice-melting power supply C1 is determined, which is the iced end far away from the distribution transformer of the iced line in the distribution substation, and the total active load and reactive load of the line at the rear end of the ice-melting power supply is P h and Q h , and the total active load and reactive load of the line at the front end of the ice-melting power supply (between the distribution transformer and the node of the ice-melting power supply vehicle C1) is P f and Q f .

[0105] S31: If only one power supply is put into, the total active power P C output by the ice-melting power supply at this time is calculated as follows:

[0106]

[0107] The active power P T which needs to be sent back to the upper power grid by the distribution transformer at this time is

[0108]

[0109] The reactive power in the line at this time can be provided by the ice-melting power supply and the distribution transformer, and the relationship can be expressed as follows:

[0110]

[0111] Wherein, Q C is the reactive power generated by the ice-melting power supply vehicle C1.

[0112] The total apparent power S T of the distribution transformer at this time can be expressed as:

[0113]

[0114] If the total apparent power S T of the distribution transformer at this time is greater than its rated capacity S0, the distribution transformer is overloaded, which may cause damage to the distribution transformer, so that the single ice-melting power supply cannot be used to realize the line ice-melting operation without power cut, and therefore two ice-melting power supplies need to be put into to carry out the line ice-melting operation without power cut.

[0115] S32: If operating only one de-icing power supply would overload the distribution transformer, it is necessary to consider operating two power supplies for uninterrupted de-icing operations. Similarly, if the position of de-icing power supply C1 remains unchanged, and if power supply C1 is still used as a power output device, its total active power output P needs to be [amount missing]. C The calculation method is as follows:

[0116]

[0117] The ice-melting power supply C2 is located at the low-voltage side distribution box of the distribution transformer, and it absorbs active power P. C2 The active power P fed back to the upper-level power grid by the distribution transformer T The relationship between the active power of other de-icing lines and the active power of other lines can be expressed as:

[0118]

[0119] At this point, the reactive power in the line can be supplied by the two ice-melting power sources and the distribution transformer. Their relationship can be expressed by the following formula:

[0120]

[0121] In the formula Q C2 This refers to the reactive power generated by the ice-melting power supply C2.

[0122] The total apparent power S of the distribution transformer T The selection should be made after comprehensive consideration, ensuring that it is less than the rated capacity S0, in order to avoid overloading the distribution transformer and causing other faults.

[0123] If power supply C1 acts as a power absorption device at this time, and the position of de-icing power supply C2 remains unchanged, then the active power P generated by de-icing power supply C2 is... C2 With the active power P transmitted by the distribution transformer T The relationship between the active power of other de-icing lines and the active power of other lines can be expressed as:

[0124]

[0125] The reactive power in the line is supplied by the ice-melting power source C2 and the distribution transformer, and their relationship can be expressed by the following formula:

[0126]

[0127] The total apparent power S of the distribution transformer T The selection should be made after comprehensive consideration, ensuring that it is less than the rated capacity S0, in order to avoid overloading the distribution transformer and causing other faults.

[0128] At this time, the ice-melting power supply C1 absorbs active power P. C for:

[0129]

[0130] The cooperative control in S4 means that when one ice-melting power source is controlled separately, the output / absorption of active power and reactive power of the ice-melting power source vehicle can be slowly increased to achieve the effect of soft start, so as to avoid impact on the distribution area; when two ice-melting power source vehicles are controlled, the output / absorption of active power and reactive power of the two ice-melting power source vehicles can be slowly increased synchronously to achieve the effect of soft start, so as to avoid impact on the distribution area.

[0131] The line loading and ice-melting operation is realized by controlling the ice-covered line current to reach the ice-melting current I r or a specified value after the starting stage, so as to maintain the line load and heat quantity, realize the heating and melting effect on the ice layer, and complete the complete melting of the ice layer. If other conditions do not change, the usual operation time should be the ice-melting time T r selected in the theoretical calculation.

[0132] As shown in FIG. 2, this is a preferred embodiment 2 of the present embodiment, in which the ice-melting power source is an ice-melting power source vehicle. Figure 2

[0133] S1: In the line ice covering condition evaluation system, the line parameter information, line ice covering condition and meteorological information are obtained based on external sensors and other information input devices. The line parameter information includes the distribution area transformer capacity S0, existing load distribution condition, line type, line length L r , conductor unit length resistance value R0, conductor unit length reactance value X0, line diameter d; the line ice covering condition includes the line ice covering thickness b and the line outer diameter D after ice covering; the meteorological information includes the environment temperature t and the environment wind speed f;

[0134] S2: In the line ice covering condition evaluation system, the required ice-melting current and the ice-melting line power distribution condition are determined according to the information obtained in S1, including the required minimum ice-melting current of the ice-covered line, the line consumed active power under the ice-melting current and the line consumed reactive power.

[0135] The calculation method of the required ice-melting current is as follows:

[0136]

[0137] In the formula, Δt is the difference between the environment temperature and zero degree Celsius, T r is the selected ice-melting time, g0 is the specific gravity of ice, which can be usually taken as 0.9, R T0 is the equivalent ice layer thermal conduction thermal resistance, which is related to the conductor outer diameter and the ice layer thickness, R T1 is the equivalent thermal resistance of convection and radiation, which is related to the conductor outer diameter, the ice layer thickness and the wind speed. ​

[0138] The ice-melting line power includes ice-melting side active power P R The ice-melting line power includes ice-melting side active power P r The ice-melting line power includes ice-melting side active power P r The ice-melting line power includes ice-melting side active power P

[0139] The ice-melting line power includes ice-melting side active power P R The calculation method is as follows:

[0140]

[0141] In the formula, U is the line voltage of the ice-melting power supply output, and for a low-voltage line of a distribution network, the line voltage is usually in the range of 380-400 V.

[0142] The ice-melting line power includes ice-melting side active power P r The calculation method is as follows:

[0143]

[0144] The ice-melting line power includes ice-melting side active power P r The calculation method is as follows:

[0145]

[0146] S3: In the line icing condition evaluation system, according to the minimum ice-melting current required by the icing line, the active power consumed by the line under the ice-melting current, and the reactive power consumed by the line, the active power and the reactive power consumed / output by the distribution transformer, the icing line, other lines in the transformer area, and the ice-melting power supply vehicle, the arrangement mode and the position of the power supply vehicle are determined, and the arrangement of the power supply vehicle is completed. The specific steps are as follows: first, the position of a ice-melting power supply vehicle C1 is determined, which is the icing end of the icing line away from the distribution transformer in the distribution transformer area, and the total active load and the total reactive load of the line at the rear end of the ice-melting power supply vehicle are P h , Q h , and the total active load and the total reactive load of the line at the front end of the ice-melting power supply vehicle (between the distribution transformer and the node of the ice-melting power supply vehicle C1) are P f , Q f .

[0147] If only one power supply vehicle is put into operation, the system structure is as shown in Figure 2 At this time, the position of the ice-melting power supply vehicle C1 is node B2, the active load and the reactive load of the line at the rear end of the ice-melting power supply vehicle are the sum of the power of the user side load 2, the user side load 3, and the subsequent user side load 4, and the active load and the reactive load of the line at the front end of the ice-melting power supply vehicle (between the distribution transformer and the node of the ice-melting power supply vehicle C1) are the power of the user side load 1.

[0148] At this time, the total active power P CThe calculation method of the total active power P

[0149]

[0150] The active power P T The active power P

[0151]

[0152] The reactive power Q

[0153]

[0154] The calculation method of the total active power P C The active power P

[0155] The total apparent power S T The total apparent power S

[0156]

[0157] The total apparent power S T If the total apparent power S

[0158] As shown in FIG. 3, it is a preferred embodiment 3 of the present embodiment, which considers that when only one power car is deployed in embodiment 2, the distribution transformer is overloaded, so that one more ice-melting power car is deployed to carry out ice-melting operation without power interruption. Figure 3

[0159] Similarly, the position of the ice-melting power car C1 is unchanged, and the position of the ice-melting power car C1 is node B3 at this time. The active load P h and the reactive load Q h of the line behind the ice-melting power car are the power of the subsequent user-side load 4. The active load P f and the reactive load Q f of the line in front of the ice-melting power car are the sum of the power of the user-side load 1, the user-side load 2, and the user-side load 3. If the ice-melting power car C1 is used as a power output device at this time, the total active power P C The calculation method of the total active power P

[0160]

[0161] The ice-melting power car C2 is arranged at the distribution box on the low-voltage side of the distribution transformer, which absorbs the active power P​C2 The relationship between the active power P T supplied by the distribution transformer to the upper-level power grid and the active power of other deicing lines can be expressed as:

[0162]

[0163] At this time, the reactive power in the line can be provided by the two deicing power supply vehicles and the distribution transformer, and the relationship can be expressed by the following formula:

[0164]

[0165] In the formula, Q C2 is the reactive power emitted by the deicing power supply vehicle C2.

[0166] In which the total apparent power S T of the distribution transformer needs to be considered comprehensively and selected to ensure that it is less than the rated capacity S0, so as to avoid overloading of the distribution transformer and causing other faults.

[0167] If the power supply vehicle C1 acts as a power absorption device at this time, and the position of the deicing power supply vehicle C2 is unchanged, the active power P C2 emitted by the deicing power supply vehicle C2 is: T The relationship between the active power P T supplied by the distribution transformer to the upper-level power grid and the active power of other deicing lines can be expressed as:

[0168]

[0169] The reactive power in the line is provided by the deicing power supply vehicle C2 and the distribution transformer, and the relationship can be expressed by the following formula:

[0170]

[0171] In which the total apparent power S T of the distribution transformer needs to be considered comprehensively and selected to ensure that it is less than the rated capacity S0, so as to avoid overloading of the distribution transformer and causing other faults.

[0172] At this time, the active power P C absorbed by the deicing power supply vehicle C1 is:

[0173]

[0174] S4: access the ice-melting power car, transmit the ice-melting current and power information to the power car cooperative control system through the line icing condition evaluation system, and the power car cooperative control system cooperatively controls the active and reactive power output / absorption of the power car participating in the ice-melting operation according to the ice-melting current and power information, the ice-melting power car provides ice-melting current to the iced distribution network area line and increases the line heating power to realize ice-melting, and the cooperative control information includes the active power output / absorption of the ice-melting power car, the reactive power output / absorption and the corresponding working time.

[0175] When a single ice-melting power car is controlled, the output / absorption of active and reactive power of the ice-melting power car can be slowly increased to achieve soft start effect and avoid impact on the distribution area; when two ice-melting power cars are controlled, the output / absorption of active and reactive power of the two ice-melting power cars can be slowly increased synchronously to achieve soft start effect and avoid impact on the distribution area.

[0176] The line loading and ice-melting operation is realized by keeping the icing line current after the starting stage to reach the ice-melting current I r or the specified value, to maintain the line load and heat absorption, realize the heating and melting effect on the icing layer, and complete the complete melting of the icing, and the usual operation time should be the ice-melting time T r selected in the theoretical calculation.

[0177] In practical application, when a single ice-melting power car is used for non-power-off ice-melting operation, a diesel generator car and other continuous power generation power cars are used with the same period and grid-connected devices; when two ice-melting power cars are used for non-power-off ice-melting operation, two energy storage power cars are used, which can conveniently send power to each other, form a circulating charge and discharge of energy storage power, and realize long-time sustainable ice-melting work.

Claims

1. A method for uninterrupted online de-icing of low-voltage distribution networks based on mobile power supply equipment, characterized in that, Includes the following steps: S0. Obtain meteorological information, as well as line parameter information and line icing information of the low-voltage distribution network; S1. Based on the meteorological information, the line parameter information, and the line icing information, calculate the minimum de-icing current required for the icy line and the de-icing line power under the minimum de-icing current. The de-icing line power includes the active power on the de-icing side, the active power required for line de-icing, and the reactive power required for line de-icing. S2. Select to deploy a first mobile power device to generate power, or deploy a second mobile power device and the first mobile power device to generate power and absorb power respectively, so as to provide de-icing current to the icing line based on the power of the de-icing line, thereby increasing the heating power of the icing line for de-icing operation. When choosing to deploy the first mobile power supply device for ice melting operations: The first mobile power supply device is deployed at the end of the icing line, away from the distribution transformer; The active load of the front-end line of the first mobile power device and the active load of the back-end line of the first mobile power device are obtained. The active load of the front-end line of the first mobile power device includes the user-side load between it and the distribution transformer, and the active load of the back-end line of the first mobile power device includes the user-side load at the end away from the distribution transformer. Based on the active power on the ice-melting side and the active load of the front-end line of the first mobile power device, the active power generated by the first mobile power device is calculated, and the first mobile power device is controlled to perform ice-melting operation with the calculated active power, thereby providing the active load of its front-end line and the active power on the ice-melting side. At the same time, the distribution transformer is controlled to provide the active load of the back-end line of the first mobile power device and backfeed the active power to the upper-level power grid. Obtain the reactive load of the front-end line of the first mobile power device and the reactive load of the back-end line of the first mobile power device. Calculate the total apparent power of the distribution transformer based on the reactive load of the front-end line of the first mobile power device, the reactive load of the back-end line of the first mobile power device, and the active load of the back-end line of the first mobile power device. Determine whether the total apparent power of the distribution transformer is greater than its rated capacity. If it is greater than its rated capacity, then deploy a second mobile power supply device and the first mobile power supply device to generate and absorb active power, respectively.

2. The method according to claim 1, characterized in that, The total apparent power of the distribution transformer is expressed as: ， ， ， Among them, S T P represents the total apparent power of the distribution transformer. T Q represents the active power that the distribution transformer needs to feed back to the upper-level power grid. T P represents the reactive power of the distribution transformer. R P is the active power on the ice melting side. h P represents the active load of the back-end line of the first mobile power supply device. r Q is the active power required for de-icing of the line. C Q represents the reactive power of the first mobile power supply device. r Q is the reactive power required for de-icing of the line. f and Q h These are the reactive loads of the front-end and back-end lines of the first mobile power supply device, respectively.

3. The method according to claim 1, characterized in that, When choosing to deploy a second mobile power device and the first mobile power device for power generation and power absorption respectively: Obtain the active load of the front and back ends of the first mobile power device; A coordination strategy is set, wherein the coordination strategy is to enable the first mobile power device to generate active power and the second mobile power device to absorb active power, or to enable the second mobile power device to generate active power and the first mobile power device to absorb active power. Based on the established collaborative strategy, the active power of the first mobile power device and the second mobile power device are calculated according to the active power on the ice melting side and the active load of the front and rear lines of the first mobile power device, respectively. Then, the first mobile power device and the second mobile power device are controlled to execute the established collaborative strategy to carry out ice melting operations.

4. The method according to claim 3, characterized in that, When the first mobile power supply device generates active power and the second mobile power supply device absorbs active power, the active power absorbed by the second mobile power supply device satisfies the following relationship: ， Among them, P C2 P is the active power absorbed by the second mobile power supply device. T P represents the active power that the distribution transformer needs to feed back to the upper-level power grid. R P is the active power on the ice melting side. h P represents the active load of the back-end line of the first mobile power supply device. r The active power required for de-icing the line.

5. The method according to claim 3, characterized in that, When the second mobile power device generates active power and the first mobile power device absorbs active power, the active power generated by the second mobile power device satisfies the following relationship: ， Among them, P C2 P represents the active power generated by the second mobile power supply device. T P represents the active power that the distribution transformer needs to feed back to the upper-level power grid. R P is the active power on the ice melting side. h P represents the active load of the back-end line of the first mobile power supply device. r The active power required for de-icing the line.

6. The method according to claim 1, characterized in that, The second mobile power supply device is deployed at the low-voltage side distribution box of the distribution transformer.

7. The method according to claim 1, characterized in that, The minimum de-icing current is expressed as ， Among them, I r The minimum de-icing current is given, Δt is the difference between the ambient temperature and zero degrees Celsius, and T is the minimum de-icing current. r Where R is the selected melting time, g0 is the specific gravity of the ice, and R is the specific gravity of the ice. T0 For the equivalent thermal resistance of ice layer heat conduction, R T1 The equivalent thermal resistance is for convection and radiation, D is the outer diameter of the line after icing, d is the line diameter, b is the icing thickness of the line, and R0 is the resistance per unit length of the conductor.

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