Method for simultaneously melting ice on multiple power transmission lines by alternating current without power failure

Abstract

The invention relates to the technical field of power transmission line ice melting, and provides a method for simultaneously melting ice on multiple power transmission lines in an alternating-current power-off-free mode, and the method comprises the steps: adding ice melting components at the tail ends of multiple lines in an ice melting section under the condition that the load is not changed, increasing the current of the lines in the ice melting section, and improving the ice melting efficiency of the lines in the ice melting section; the ice on the wire is removed in a self-heating mode when the wire runs in a heavy load or full load state. According to the invention, a conventional single power transmission line AC / DC power failure ice melting mode is changed, and simultaneous non-power-failure AC ice melting is carried out on a plurality of power transmission lines; according to the invention, ice melting of a plurality of lines can be rapidly, conveniently and automatically controlled at the same time, the workload of ice melting is reduced, normal operation of the lines is ensured, and the reliability of line power transmission is improved; inductive current increased by each line capable of simultaneously melting ice is compensated, and the voltage quality of each line subjected to ice melting is stabilized.

Description

Technical Field

[0001] The present invention relates to the technical field of ice melting for power transmission lines, and in particular to a method for melting ice for multiple power transmission lines while performing alternating current without power outage. Background Art

[0002] In areas prone to ice accumulation in winter, transmission lines are widely covered with ice, and the task of de-icing and melting transmission lines is extremely heavy and difficult. Large-scale line outages often occur, seriously affecting the normal production and life of power users. The power grid operation and management department urgently needs more effective ice melting technology.

[0003] Current ice melting technology:

[0004] 1. DC power outage ice melting technology:

[0005] The ice melting method for transmission lines at home and abroad is to use DC power outage to melt ice. In order to reduce the incidence of ice disasters on transmission lines and the damage caused, researchers in the power industry of various countries are studying line anti-icing and ice melting technologies to achieve the reliability and safety of high-voltage power grid operations. Serious natural rain, snow and ice disasters have occurred in Central my country, Southwest China and East China, causing serious damage to power transmission and transformation facilities. High-voltage transmission line tripping and tower collapse and line breaking are very common, seriously affecting and threatening the safe and stable operation of high-voltage transmission networks.

[0006] 2. DC ice melting technology for mobile stations and mobile power generation vehicles:

[0007] The de-icing technology for 110kV to 220kV lines currently mainly adopts inter-station mobile technology and DC de-icing solutions using mobile generators. Some also adopt AC short-circuit de-icing solutions, but the actual de-icing effect is not good.

[0008] 10kV and 35kV lines are power transmission and distribution networks. They are limited by human and material resources, and the geographical environment is complex, so there is not enough attention. In fact, these lines are directly related to users, and whether they are safe to operate directly affects the reliability of users' electricity use.

[0009] The de-icing of 10kV and 35kV lines has not received enough attention and has not been implemented on a large scale. The de-icing methods are mainly mobile DC de-icing and manual de-icing. Due to the geographical environment of the line, it is difficult for the mobile de-icing device to quickly reach the designated location where de-icing is required, and the de-icing operation is carried out frequently.

[0010] 3. Artificial deicing technology:

[0011] Manual de-icing has higher safety risks and lower efficiency. When 10kV and 35kV lines are de-iced, the load side needs to be frequently shut down to cooperate with the de-icing of the de-icing lines, causing great inconvenience and losses to the work and life of the majority of power users. The actual de-icing effect has a bad impact on power users.

[0012] In summary, the DC ice-melting technology for high-voltage transmission lines requires the establishment of an independent ice-melting power supply, ice-melting transformer, rectifier equipment and cable connection system in the substation. The line must be shut down during ice-melting, interrupting large-capacity power transmission and affecting the stable operation of the power grid. The equipment investment is large, the operation is cumbersome, and a lot of manpower and material resources are mobilized. Due to the geographical environment of the line, the mobile de-icing technology between stations and the mobile DC de-icing technology of power generators is difficult for the mobile de-icing device to quickly reach the designated location where ice melting is required, and the de-icing operation is performed frequently. Artificial de-icing technology has higher safety risks and lower efficiency. Summary of the invention

[0013] In order to solve the above problems, the present invention provides a method for melting ice on multiple power transmission lines while alternating current without power outage.

[0014] The technical solution adopted by the present invention is:

[0015] A method for melting ice on multiple transmission lines while alternating current without power outage is provided. Without changing the load size, ice-melting components are put into the ends of multiple lines in the ice-melting section to increase the current of the lines in the ice-melting section, so that the conductors can be operated under heavy load or full load to remove ice on the conductors by self-heating.

[0016] Furthermore, capacitors with sufficient capacity are connected in parallel at the hub substation, hub bus or sending end of the main transmission trunk line in the de-icing section line, and the capacitors are used to compensate for the increased inductive current of multiple de-icing lines. The capacitors can stabilize the voltage quality of the de-iced lines.

[0017] Furthermore, the ice-melting components are remotely and automatically switched on and off according to ice-melting needs through an automation system.

[0018] Furthermore, after the capacitor and ice-melting components are installed on the transmission line, the voltage change of the transmission line should be within the standard allowable range; the system flow on the power transmission side is not affected during ice melting, and the voltage quality of the load side line is guaranteed.

[0019] Furthermore, when there are multiple lines in the ice-melting section, an ice-melting component is put into use at the end of each line. The ice-melting component is a reactor located on the load side and connected in parallel with the line.

[0020] Furthermore, during the ice melting process, the electrical parameters need to be calculated to ensure the effective operation of the ice melting equipment. The steps are as follows:

[0021] Step 1 Calculation of ice melting heating power:

[0022] Based on Joule's law, the square of the current passing through the resistor multiplied by the resistance value gives the heat generated on the resistor, which is the heat required in the ice melting process.

[0023] P 融冰 =|I0| 2 ·R

[0024] Where P 融冰 is the heat generated by the ice-melting equipment; I0 ​​is the ice-melting current allowed by the ice-melting circuit; R is the resistance, which indicates the effective resistance of the circuit;

[0025] Step 2 Calculation of current on the shunt reactor:

[0026] In the reactor, the current is calculated from the relationship between voltage and reactance, and the current on the reactor is expressed in imaginary form to reflect its phase characteristics;

[0027]

[0028] In the formula, I L Represents the current flowing through the shunt reactor; V Ld is the voltage on the power consumption side; j represents the imaginary unit; 2π is a constant used to convert the frequency into angular frequency; f is the AC frequency of the power supply; L is the inductance of the reactor; I Ld It is the resistive current on the power consumption side;

[0029] Further deduction:

[0030]

[0031] Step 3: Calculate the inductance of the reactor:

[0032] The required inductance value L is obtained from the relationship between the voltage and the current flowing through the reactor;

[0033]

[0034] Step 4: Calculate capacitor capacity:

[0035] Based on the relationship between compensation current, voltage and capacitance, the required capacitance value is calculated by using the known current and voltage;

[0036]

[0037] In the formula, C is the capacitance of the capacitor; K is the reactive current I of the reactor L The degree of compensation; L is the reactive current of the reactor; V S is the bus voltage on the transmission side;

[0038] The above calculations can be used to determine the electrical parameters during the ice melting process. By properly selecting the parameters of the inductor and capacitor, the performance of the ice melting equipment can be optimized to ensure that sufficient heat is generated when needed.

[0039] Furthermore, between the calculation of the inductance value of the reactor in step 3 and the calculation of the capacitor capacity in step 4, it is also necessary to deduce the relationship between the reactive current of the reactor and the current of the capacitor. The process is as follows:

[0040] Assume the reactor reactive current I L The compensation degree is K, then 0<K<I L ;

[0041] The required capacitor current I C The size is related to the compensation degree K and the reactive current of the reactor, which can be expressed as:

[0042] I C =j·K·|I L |

[0043] At the same time, the capacitor current I C The size is related to the bus voltage V s , frequency f and capacitor capacity C are related and can be expressed as:

[0044] I C =V s ·j(2πf)C

[0045] The magnitude of the compensation current is related to the power supply voltage and the capacitance value, which can be expressed as:

[0046] K·|I L |=|V s |·(2πf)C

[0047] Therefore, the capacitor current I C Sufficient to compensate the reactive current I of the reactor L The compensation part is determined by the compensation degree K.

[0048] The beneficial effects of the present invention are:

[0049] The method of simultaneously melting ice on multiple transmission lines without power outage can be used for melting ice on multiple transmission lines of 35KV, 110KV and 220KV without power outage, changing the previous method of melting ice on single transmission line with AC or DC power outage, and performing simultaneous AC melting on multiple transmission lines without power outage.

[0050] The method for melting ice on multiple transmission lines while alternating current without power outage can automatically control the ice-melting of multiple lines quickly and conveniently at the same time, thereby reducing the workload of ice-melting, ensuring the normal operation of the lines, and improving the reliability of line power transmission.

[0051] The method of melting ice on multiple transmission lines simultaneously without power outage does not require a special ice-melting power supply. It uses the transmission voltage of the transmission line itself. Without changing the load size, it increases the current of the lines in the ice-melting section by investing ice-melting components (parallel inductive current reactors) at the ends of multiple lines in the ice-melting section. The conductors are self-heated when running under heavy or full load conditions to remove ice on the conductors. Capacitors of sufficient capacity are connected in parallel at the hub substation, hub bus, and main transmission trunk line sending end in the ice-melting area to compensate for the increased inductive current of each simultaneously ice-melting line and stabilize the voltage quality of each ice-melting line.

[0052] The method of melting ice on multiple transmission lines simultaneously without power outage does not affect the power flow of the main transmission side system during ice melting, and at the same time ensures the voltage quality of the load side line (that is, the voltage change is within the standard allowable range). After removing the ice on the wire, the ice melting components are removed to restore the original state of the line, and the normal power consumption of the end users is not affected during the ice melting process.

[0053] The method of melting ice on multiple transmission lines simultaneously without power outage has extremely wide application space and huge product market in transmission and distribution lines of different voltage levels. It will make fundamental and effective changes to the way of ice melting in power grids and promote the leapfrog development of ice melting technology in power grids. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0055] in:

[0056] Figure 1 and Figure 2 It is a schematic diagram of the connection of ice-melting components when there are multiple lines in the ice-melting section;

[0057] Figure 3 This is a schematic diagram of the connection of ice-melting components in the ice-melting section of a 10KV transmission line;

[0058] Figure 4 The current of the capacitor, the current flowing through the reactor, the system current on the power transmission side, and the

[0059] The relationship diagram between the allowable ice melting current of the ice line and the resistive current on the power consumption side. DETAILED DESCRIPTION

[0060] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0061] The present embodiment provides a method for simultaneously melting ice on multiple transmission lines without power outages. The method for simultaneously melting ice on multiple transmission lines without power outages increases the current of the lines in the ice-melting section by investing ice-melting components at the ends of multiple lines in the ice-melting section without changing the load size, so that the conductors can be operated under heavy load or full load to remove ice on the conductors by self-heating.

[0062] Specifically, Figure 1 and Figure 2 As shown, when there are multiple lines in the de-icing section, de-icing components are put into use at the end of each line. The de-icing components are reactors L1, L2 and L3 located on the load side and connected in parallel with the line. Furthermore, in order to stabilize the voltage quality of the de-iced line, as shown in FIG. Figure 1 and Figure 2 As shown, a capacitor C with sufficient capacity is connected in parallel at the hub substation, hub bus or sending end of the main transmission trunk line in the de-icing section line, and the capacitor is used to compensate for the increased inductive current of multiple de-icing lines. The capacitor can stabilize the voltage quality of the de-iced lines.

[0063] For 10KV transmission lines, such as Figure 3 As shown, on the power transmission side, the capacitor C is connected through the combination switch CB1, and the capacitor discharge resistor R is connected through the combination switch CB2. c ; On the load side, the inductor L is connected through the combination switch CB3, and the inductor discharge resistor R is connected through the combination switch CB4 L .

[0064] It should be noted that no matter there are multiple lines or 10KV transmission lines in the ice-melting section, after the capacitors and parallel reactors are installed on the transmission lines, the voltage change of the transmission lines should be within the standard allowable range; so that the system flow on the transmission side is not affected during ice melting, and the voltage quality of the load-side lines is guaranteed.

[0065] In addition, in order to achieve automatic control, the ice-melting components are remotely and automatically switched on and off through the automation system according to the needs of ice melting. The automation system can be implemented using a PLC programmable logic controller or an RTU remote terminal unit in conjunction with actuators such as electromagnetic relays.

[0066] Furthermore, the capacitor current I C , the current flowing through the reactor I L, the system current I on the power transmission side, the de-icing current I0 allowed by the de-icing line, and the resistive current I on the power consumption side Ld Relationship Figure 4 As shown; During the ice melting process, the electrical parameters need to be calculated to ensure the effective operation of the ice melting equipment. The steps are as follows:

[0067] Assume that the voltage on the power consumption side is V Ld , current I Ld is a resistive current (the load power factor is not considered for simplified calculation), and the ice-melting current allowed for the ice-melting line is I0;

[0068] Step 1 Calculation of ice melting heating power:

[0069] Based on Joule's law, the square of the current passing through the resistor multiplied by the resistance value gives the heat generated on the resistor, which is the heat required in the ice melting process.

[0070] P 融冰 =|I0| 2 ·R

[0071] Where P 融冰 is the heat generated by the ice-melting equipment; I0 ​​is the ice-melting current allowed by the ice-melting circuit; R is the resistance, which indicates the effective resistance of the circuit;

[0072] Step 2 Calculation of current on the shunt reactor:

[0073] In the reactor, the current is calculated from the relationship between voltage and reactance, and the current on the reactor is expressed in imaginary form to reflect its phase characteristics;

[0074]

[0075] In the formula, I L Represents the current flowing through the shunt reactor; V Ld is the voltage on the power consumption side; j represents the imaginary unit; 2π is a constant used to convert the frequency into angular frequency; f is the AC frequency of the power supply; L is the inductance of the reactor; I Ld It is the resistive current on the power consumption side;

[0076] Further deduction:

[0077]

[0078] Step 3: Calculate the inductance of the reactor:

[0079] The required inductance value L is obtained from the relationship between the voltage and the current flowing through the reactor;

[0080]

[0081] In addition, it is necessary to deduce the relationship between the reactive current of the reactor and the current of the capacitor. The process is as follows:

[0082] Assume the reactor reactive current I L The compensation degree is K, then 0<K<I L ;

[0083] The required capacitor current I C The size is related to the compensation degree K and the reactive current of the reactor, which can be expressed as:

[0084] I C =j·K·|I L |

[0085] At the same time, the capacitor current I C The size is related to the bus voltage V s , frequency f and capacitor capacity C are related and can be expressed as:

[0086] I C =V s ·j(2πf)C

[0087] The magnitude of the compensation current is related to the power supply voltage and the capacitance value, which can be expressed as:

[0088] K·|I L |=|V s |·(2πf)C

[0089] Therefore, the capacitor current I C Sufficient to compensate the reactive current I of the reactor L The compensation part is determined by the compensation degree K.

[0090] Step 4: Calculate capacitor capacity:

[0091] Based on the relationship between compensation current, voltage and capacitance, the required capacitance value is calculated by using the known current and voltage;

[0092]

[0093] In the formula, C is the capacitance of the capacitor; K is the reactive current I of the reactor L The degree of compensation; L is the reactive current of the reactor; V S is the bus voltage on the transmission side;

[0094] The above calculations can be used to determine the electrical parameters during the ice melting process. By properly selecting the parameters of the inductor and capacitor, the performance of the ice melting equipment can be optimized to ensure that sufficient heat is generated when needed.

[0095] In summary, the method of melting ice on multiple transmission lines simultaneously without AC power outage does not rely on an additional ice-melting power supply system, simplifies the ice-melting equipment, and the fixed configuration of the ice-melting equipment can quickly and conveniently melt the ice on the distribution network lines. When the ice and snow weather season comes, the AC online non-stop power-off ice-melting device is put into operation to perform online ice-melting. The lines are not shut down during the ice and snow season to melt the ice and ensure normal power supply to users. By melting ice without power outage, the transmission lines will not suffer ice disasters such as pole collapse and line breakage during the ice and snow season.

[0096] During ice melting, the parallel-connected reactors and capacitors not only form an online AC ice melting function, but also serve as part of the power grid and are included in the operation of the power grid. The ice melting devices of multiple transmission lines are remotely and automatically switched on and off according to the needs of ice melting through the automation system. The voltage at both ends of the ice melting line, the line current, the line power transmission power and the line temperature, the switch status of the ice melting device, the current of the device components, and other telemetry and telesignaling information are connected to the power grid automation system in real time, and the automation system remotely switches the ice melting device.

[0097] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for melting ice on multiple power transmission lines simultaneously without power outage, characterized in that: Without changing the load size, de-icing components are added to the ends of multiple lines in the de-icing section to increase the current of the lines in the de-icing section, so that the conductors can be operated under heavy or full load conditions to remove ice on the conductors by self-heating.

2. The method for melting ice on multiple power transmission lines simultaneously without power outage according to claim 1, characterized in that: Capacitors with sufficient capacity are connected in parallel at the hub substation, hub bus or sending end of the main transmission trunk line in the de-icing section line. The capacitors are used to compensate for the increased inductive current of multiple de-icing lines. The capacitors can stabilize the voltage quality of the de-iced lines.

3. The method for melting ice on multiple power transmission lines simultaneously without power outage according to claim 2, characterized in that: The ice-melting components are remotely and automatically switched on and off according to ice-melting needs through an automation system.

4. The method for melting ice on multiple power transmission lines simultaneously without power outage according to claim 2, characterized in that: After the capacitor and ice-melting components are installed on the transmission line, the voltage change of the transmission line should be within the standard allowable range; when melting ice, the system flow on the power transmission side is not affected, and the voltage quality of the load side line is guaranteed.

5. The method for melting ice on multiple power transmission lines simultaneously without power outage according to claim 2, characterized in that: When there are multiple lines in the ice-melting section, ice-melting components are put into use at the end of each line. The ice-melting components are reactors located on the load side and connected in parallel with the lines.

6. The method for melting ice on multiple power transmission lines simultaneously without power outage according to claim 5, characterized in that: During the ice melting process, the electrical parameters need to be calculated to ensure the effective operation of the ice melting equipment. The steps are as follows: Step 1 Calculation of ice melting heating power: Based on Joule's law, the square of the current passing through the resistor multiplied by the resistance value gives the heat generated on the resistor, which is the heat required in the ice melting process. P 融冰 =|I0| 2 ·R Where P 融冰 is the heat generated by the ice-melting equipment; I0 ​​is the ice-melting current allowed by the ice-melting circuit; R is the resistance, which indicates the effective resistance of the circuit; Step 2 Calculation of current on the shunt reactor: In the reactor, the current is calculated from the relationship between voltage and reactance, and the current on the reactor is expressed in imaginary form to reflect its phase characteristics; In the formula, I L Represents the current flowing through the shunt reactor; V Ld is the voltage on the power consumption side; j represents the imaginary unit; 2π is a constant used to convert the frequency into angular frequency; f is the AC frequency of the power supply; L is the inductance of the reactor; I Ld It is the resistive current on the power consumption side; Further deduction: Step 3: Calculate the inductance of the reactor: The required inductance value L is obtained from the relationship between the voltage and the current flowing through the reactor; Step 4: Calculate capacitor capacity: Based on the relationship between compensation current, voltage and capacitance, the required capacitance value is calculated by using the known current and voltage; In the formula, C is the capacitance of the capacitor; K is the reactive current I of the reactor L The degree of compensation; L is the reactive current of the reactor; V S is the bus voltage on the transmission side; The above calculations can be used to determine the electrical parameters during the ice melting process. By properly selecting the parameters of the inductor and capacitor, the performance of the ice melting equipment can be optimized to ensure that sufficient heat is generated when needed.

7. The method for melting ice on multiple power transmission lines simultaneously without power outage according to claim 6, characterized in that: Between the calculation of the inductance value of the reactor in step 3 and the calculation of the capacitor capacity in step 4, it is also necessary to deduce the relationship between the reactive current of the reactor and the current of the capacitor. The process is as follows: Assume the reactor reactive current I L The compensation degree is K, then 0<K<I L ; The required capacitor current I C The size is related to the compensation degree K and the reactive current of the reactor, which can be expressed as: I C =j·K·|I L | At the same time, the capacitor current I C The size is related to the bus voltage V s , frequency f and capacitor capacity C are related and can be expressed as: I C =V s ·j(2πf)C The magnitude of the compensation current is related to the power supply voltage and the capacitance value, which can be expressed as: K·|I L |=|V s |·(2πf)C Therefore, the capacitor current I C Sufficient to compensate the reactive current I of the reactor L The compensation part is determined by the compensation degree K.

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