35kV transformer substation dual-power-supply angular-difference loop-closing uninterruptible power supply reversing method and system

Abstract

The invention relates to a 35kV transformer substation dual-power-supply angular-difference loop-closing uninterruptible power supply reversing method and system, and the method comprises the steps: 1, building a loop diagram model; loop impedance is calculated, the power flow direction is analyzed, and a loop closing current value is calculated; 2, selecting a loop closing operation moment according to a line load curve, and calculating load current of each section of line in a loop; 3, calculating the comprehensive current of each line, and checking the line bearing capacity; 4, calculating a loop-opening constant value, and setting the loop-opening constant value to a special constant value area in the dual-power line switch protection device for standby application; and step 5, switching on the to-be-tripped line switch if the current surge at the moment of loop closing exceeds a switch operating value, and switching the dual-power switch protection to a normal constant value area after the loop closing operation is finished. According to the invention, the continuity of system operation and the reliability of power supply can be maintained, the automatic switching of main and backup power is realized, the economic loss is reduced, and meanwhile, the method does not need operation and maintenance personnel to carry out field operation any more, and the waste of human resources is also greatly reduced.

Description

Technical Field

[0001] The invention relates to the technical field of transformer substation operation, and in particular to a method and system for uninterrupted power supply reversal of dual power supplies with angle difference closing loop in a 35kV transformer substation. Background Art

[0002] In the power system, when the two incoming power lines of the 35kV substation come from different groups of transformers, there is a 30° angle difference. Direct closing operation will generate closing current, which may cause protection misoperation or equipment damage. According to power regulations, the first-break-then-close method can only be used when performing power reversal operation on the above wiring method, resulting in a short-term power outage, which seriously affects the reliability and continuity of power grid operation.

[0003] In addition, in order to reduce the impact on users, power outages and load reversal are generally carried out at night. However, for first-level power users who have extremely high requirements for power supply reliability, this method will have a great impact on their production and life; at the same time, operation and maintenance personnel sometimes need to go to the site to operate, which greatly increases the workload of operation and maintenance personnel. In general, the continuous load adjustment of 35kV substations is an urgent problem to be solved.

[0004] In recent years, with the increasing requirements of users for power reliability and the updating of power grid systems, the existing 35kV substations have basically achieved dual power supply, with one main supply and one backup supply under normal operation. This has also increased the demand for load reversal methods without power outages.

[0005] CN 115313368A discloses a method for adjusting loads without power outages in a 10kV line with a 30-degree angle difference. First, the relevant line protection setting values ​​in the loop and the protection action setting values ​​of the circuit protection device are checked, and then the closing current is calculated. By temporarily modifying the line protection setting values ​​and the protection setting values ​​of the loop-breaking switch, the loop-breaking switch is tripped earlier than other switches when the closing switch is closed, thereby completing the power outage adjustment operation. The disadvantage of the prior art is that it is only applicable to the 10kV voltage level, and the closing current and load current under the high voltage level are not comprehensively considered for checking. Summary of the invention

[0006] In order to solve the deficiencies in the prior art, the present invention proposes a method for 35kV substation dual power supply with angle difference closing loop without power failure and power reversal. By analyzing some typical networks with 30° angle difference in the power grid, the network structure is extracted, and the closing loop current is calculated according to the relevant parameters in the structure. At the same time, the overload capacity of the relevant line protection setting value, the main transformer in the loop, and the line is checked. According to the analysis results, corresponding measures are taken to ensure that the protection does not malfunction during the closing and opening loop operation and the related equipment is not overloaded. The setting value is corrected, and the quick-break characteristics of the relay protection device are used to use the closing loop current to trip the switch that needs to disconnect the power supply to achieve closing loop and power reversal.

[0007] The present invention adopts the following technical solution. In a first aspect, the present invention provides a 35kV substation dual power supply with angle difference loop without power failure and power switching method, comprising the following steps:

[0008] Step 1: Establish a loop diagram model based on the actual power grid connection; calculate the loop impedance, analyze the power flow direction and calculate the closed loop current value;

[0009] Step 2, according to the line load curve, select the closing operation time and calculate the load current of each line section in the loop;

[0010] Step 3, calculating the comprehensive current of each line according to the closed loop current in step 1 and the load current of each line in the loop in step 2, and checking the line carrying capacity;

[0011] Step 4, taking into account the rated current of the dual power supply line of the substation to be closed and the protection setting of the upper line, the ring-opening setting is calculated and set to the dedicated setting area in the dual power supply line switch protection device for standby;

[0012] Step 5: Before closing the loop, switch the protection setting of the line to be tripped to the special setting area of ​​the switch protection closing loop and power supply reversal, and temporarily exit the line protection to be put into use; perform the closing loop operation, the instantaneous current surges and exceeds the switch action value, and the switch of the line to be tripped is opened to achieve power supply reversal without power outage; after the closing loop operation is completed, the dual power switch protection is switched to the normal setting area.

[0013] Preferably, the closed-loop current value is expressed by the following formula:

[0014] I h =1560×0.5176 / Z

[0015] Where:

[0016] 1560 is the 35KV reference parameter; 0.5176 is the approximate value of 2*sin15; Z is the loop impedance.

[0017] Preferably, the loop closing operation time in step 2 is selected according to the D5000 system line load curve, and the loop closing operation is performed during a period when the load is less than the average load in a day.

[0018] Preferably, in step 3, the verification condition is set as: the short-term overload multiple is not greater than the instantaneous overload 2.0.

[0019] Preferably, the short-time overload multiple is expressed by the following formula:

[0020] K=I z / I0

[0021] Where:

[0022] K represents the short-time overload multiple; Iz represents the comprehensive current of the circuit; I0 ​​represents the allowable current.

[0023] Preferably, the loop integrated current is expressed by the following formula:

[0024] I z =I h +I p

[0025] Where:

[0026] Iz represents the integrated current of the loop;

[0027] Ih represents the closed loop current;

[0028] Ip represents the load current.

[0029] Preferably, in step 4, the setting of the protection setting value only considers the maximum load current allowed by the entire loop. If the protection action condition is not met, the maximum operating current in the entire loop is considered. The protection action time is 0-1.2S.

[0030] The second aspect of the present invention provides a 35kV substation dual power supply with angle difference loop uninterruptible power supply system, and the method for running the 35kV substation dual power supply with angle difference loop uninterruptible power supply method comprises: a model building module, a data calculation module, and a result output module;

[0031] The model building module is used to build a power grid loop diagram model;

[0032] The data calculation module is used to calculate the closed-loop current, load current, comprehensive current of each line, short-time overload multiple and open-loop setting value;

[0033] The result output module is used to output protection setting switching signals and closing-loop operation control signals.

[0034] Compared with the prior art, the beneficial effects of the present invention include at least: it can maintain the continuity of system operation and the reliability of power supply to the maximum extent, realize the self-switching of main and backup power, and realize load reversal operation without user perception, thereby reducing the impact of power outages on users, especially important users, and reducing economic losses; verifying the line load, improving the safety of loop operation, and ensuring that other protection equipment does not malfunction; at the same time, this method no longer requires operation and maintenance personnel to perform on-site operations, which greatly reduces the waste of human resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a flow chart of a method for closing a 35kV substation uninterruptible dual power supply with angle difference according to an embodiment of the present invention;

[0036] Figure 2 It is a substation loop model diagram provided according to an embodiment of the present invention. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The embodiments described in this application are only part of the embodiments of the present invention, not all of them. Based on the spirit of the present invention, other embodiments obtained by ordinary technicians in this field without creative work are all within the scope of protection of the present invention.

[0038] like Figure 1 As shown, Embodiment 1 of the present invention provides a 35kV substation dual power supply with angle difference loop without power failure and power switching method, including the following steps:

[0039] Step 1: Establish a loop diagram model based on the actual power grid connection; calculate the loop impedance, analyze the power flow direction and calculate the closed-loop current value.

[0040] Preferably, but not limited to, using viso to build a loop graph model such as Figure 2 As shown in the figure, the 35KV C station (two incoming lines with a phase difference of 30°) is powered by 363 B C line and 364 D C line. The long mode is powered by 364 D C line, and 363 B C line is in hot standby. If the power supply mode is to be changed, and the 363 line is used to supply the entire station, all low-voltage outgoing lines and main transformer switches of the station need to be opened in sequence according to the conventional method, and finally the 364 switch is opened, and the 363 switch is closed, and then the power is supplied in sequence according to the voltage level.

[0041] Preferably, the loop impedance is expressed as follows,

[0042] Z=R+jX

[0043] Where:

[0044] R is the loop resistance;

[0045] X is reactance;

[0046] j is the imaginary unit.

[0047] Because the phase of line 364D-C is 30° ahead of that of line 363B-C, the circulation direction is counterclockwise.

[0048] Preferably, the closed-loop current value is expressed by the following formula:

[0049] I h =1560×0.5176 / Z

[0050] Where:

[0051] 1560 is the 35KV reference parameter;

[0052] 0.5176 is the approximate value of 2*sin15, preferably, four decimal places are retained;

[0053] Z is the loop impedance.

[0054] Step 2: According to the line load curve, select the closing operation time and calculate the load current of each line section in the loop.

[0055] Preferably, according to the D5000 system line load curve, the loop closing operation is performed during a period when the load is less than the average load in a day.

[0056] It is worth noting that the use of any means to calculate the load current, such as but not limited to the use of PQ decomposition method, Newton method, rapid decomposition flow algorithm, manual or software simulation to calculate the load current, is a conventional technical means that can be easily thought of by those skilled in the art and should fall within the scope of protection of the present invention.

[0057] Step 3, calculate the comprehensive current of each line according to the closed loop current in step 1 and the load current of each line in the loop in step 2, and then check the line carrying capacity.

[0058] Preferably, the verification condition is set as follows: the short-term overload multiple is not greater than the instantaneous overload 2.0.

[0059] Specifically, the verification is divided into two situations, namely before and after the reverse supply.

[0060] Before the reverse supply, the 35kV system takes the average voltage of 36.5kV of the 35kV busbar of transformer A during normal operation. Because the resistance accounts for a large proportion of the 35kV line impedance, in order to simplify the calculation, only the resistance value is taken into account and the reactance value is ignored. The short-term overload multiple is expressed by the following formula:

[0061] K=I z / I0

[0062] Where:

[0063] K represents the short-time overload multiple;

[0064] I z Indicates the integrated current of the loop;

[0065] I0 represents the allowable current.

[0066] Preferably, I0 is 403A.

[0067] Further preferably, the loop integrated current is expressed by the following formula:

[0068] I z =I h +Ip

[0069] Where:

[0070] I z Indicates the integrated current of the loop;

[0071] I h Indicates the closed loop current;

[0072] I p Indicates the load current.

[0073] It can be understood by those skilled in the art that, after calculation, it can be seen that when the power supply mode is changed in the conventional manner, the short-term overload multiple of some circuits is greater than the instantaneous overload 2.0, and the verification conditions cannot be met.

[0074] After the reverse supply, the load current value decreases to meet the instantaneous overload requirements.

[0075] Step 4, taking into account the rated current of the dual power supply line of the substation to be closed and the protection setting of the upper line, calculate the ring release setting, and set it to the special setting area in the dual power supply line switch protection device for standby.

[0076] Preferably, the setting of the protection setting value only considers the maximum load current allowed by the entire loop. If the protection action conditions are not met, the maximum operating current in the entire loop can be considered; the protection action time can be comprehensively considered and taken as 0-1.2S.

[0077] Specifically, switch 363 of line B and C at station C is set as a de-looping switch, and the set value zone is set in zone 1. According to statistical values, the load current of switch 363 is no more than 30A in the early morning. In order to quickly trip switch 363 to de-loop the loop when the protection device reliably senses the closing current at the moment of closing the loop, the set value of switch 363 is set to 80A according to the load current, and the time limit is 0.1s; the set value of switch 362 is set to 200A, and the time limit is 0.3S.

[0078] Step 5: Before closing the loop, switch the protection setting of the line to be tripped to the special setting area of ​​the switch protection closing loop and power supply reversal, and temporarily exit the line protection to be put into use; perform the closing loop operation, the instantaneous current surges and exceeds the switch action value, and the switch of the line to be tripped is opened to achieve power supply reversal without power outage; after the closing loop operation is completed, the dual power switch protection is switched to the normal setting area.

[0079] Preferably, before implementing the angle difference closing operation, the power grid status is comprehensively monitored, including current, voltage, frequency, and phase angle parameters. Through real-time monitoring, the stability and reliability of the power grid can be more accurately evaluated, thereby making more accurate decisions. During the implementation of the angle difference closing operation, the current, voltage parameters and the operating status of the equipment are also required to be monitored in real time. If an abnormal situation occurs during the operation, the operation is stopped immediately and processed.

[0080] It is worth noting that in order to reduce the workload of maintenance personnel in modifying temporary set values ​​on site during the process of de-closing and closing the loop, a set value set in other set value areas is re-issued for the switches (configured with protection) that need to be de-closing in the loop, which is specifically used for shutdown and startup by operating personnel when de-closing the loop.

[0081] Embodiment 2 of the present invention provides a 35kV substation dual power supply with angle difference loop uninterruptible power supply system, including: a model building module, a data calculation module, and a result output module.

[0082] The model building module is used to build a power grid loop diagram model;

[0083] The data calculation module is used to calculate the closed-loop current, load current, comprehensive current of each line, short-time overload multiple and open-loop setting value;

[0084] The result output module is used to output protection setting switching signals and closing-loop operation control signals.

[0085] The beneficial effects of the present invention are that, compared with the prior art, it can maintain the continuity of system operation and the reliability of power supply to the maximum extent, realize the self-switching of main and backup power, and implement load reversal operation without user perception, thereby reducing the impact of power outages on users, especially important users, and reducing economic losses; verifying the line load, improving the safety of loop closing operations, and ensuring that other protection devices do not malfunction; at the same time, the method no longer requires operation and maintenance personnel to perform on-site operations, which greatly reduces the waste of human resources.

[0086] The present disclosure may be a system, a method and / or a computer program product. The computer program product may include a computer-readable storage medium carrying computer-readable program instructions for causing a processor to implement various aspects of the present disclosure.

[0087] A computer-readable storage medium may be a tangible device that can hold and store instructions used by an instruction execution device. A computer-readable storage medium may be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. More specific examples of computer-readable storage media (a non-exhaustive list) include: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a static random access memory (SRAM), a portable compact disk read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanical encoding device, such as a punch card or a raised structure in a groove on which instructions are stored, and any suitable combination of the foregoing. As used herein, a computer-readable storage medium is not to be interpreted as a transient signal per se, such as a radio wave or other freely propagating electromagnetic wave, an electromagnetic wave propagating through a waveguide or other transmission medium (e.g., a light pulse through a fiber optic cable), or an electrical signal transmitted through a wire.

[0088] The computer-readable program instructions described herein can be downloaded from a computer-readable storage medium to each computing / processing device, or downloaded to an external computer or external storage device via a network, such as the Internet, a local area network, a wide area network, and / or a wireless network. The network can include copper transmission cables, optical fiber transmissions, wireless transmissions, routers, firewalls, switches, gateway computers, and / or edge servers. The network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards the computer-readable program instructions for storage in the computer-readable storage medium in each computing / processing device.

[0089] The computer program instructions for performing the operation of the present disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-related instructions, microcode, firmware instructions, state setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages, such as Smalltalk, C++, etc., and conventional procedural programming languages, such as "C" language or similar programming languages. Computer-readable program instructions may be executed completely on a user's computer, partially on a user's computer, as an independent software package, partially on a user's computer, partially on a remote computer, or completely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer via any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., using an Internet service provider to connect via the Internet). In some embodiments, an electronic circuit, such as a programmable logic circuit, a field programmable gate array (FPGA), or a programmable logic array (PLA), may be customized by utilizing the state information of the computer-readable program instructions, and the electronic circuit may execute the computer-readable program instructions, thereby realizing various aspects of the present disclosure.

[0090] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A 35kV substation dual power supply with angle difference loop without power failure and power switching method, characterized in that: The following steps are involved: Step 1, establishing a loop diagram model according to actual power grid wiring; Calculate the closing current value; step 2, according to the line load curve, select the closing operation time and calculate the load current of each section of the line in the loop; step 3, calculate the comprehensive current of each line according to the closing current and the load current of each section of the line in the loop, and check the line carrying capacity; step 4, taking into account the rated current of the dual power supply line of the substation to be closed and the protection setting of the upper line, calculate the loop release setting, and set it to the special setting area in the dual power supply line switch protection device for standby; step 5, switch the protection setting of the line to be tripped to the special setting area of ​​the switch protection closing and reversing, and perform the closing operation. The current surge exceeds the switch action value, and the switch of the line to be tripped is opened to achieve non-stop power reversal.

2. A 35kV substation dual power supply with angle difference loop non-interruptible power supply method according to claim 1, characterized in that: In step 1, the closed loop current value is expressed by the following formula: I h =1560×0.5176 / Z Where: Z is the loop impedance.

3. A 35kV substation dual power supply with angle difference loop non-interruptible power supply method according to claim 1, characterized in that: In step 2, the closing operation time is selected according to the line load curve of the smart grid dispatching control system, and the closing operation is performed during the period when the load is less than the average load in a day.

4. A 35kV substation dual power supply with angle difference loop non-interruptible power supply method according to claim 1, characterized in that: In step 3, the verification condition is set as: the short-term overload multiple is not greater than the instantaneous overload 2.

0.

5. A 35kV substation dual power supply with angle difference loop non-stop power supply method according to claim 4, characterized in that: The short-time overload multiple is expressed by the following formula: K=I z / I0 Where: K represents the short-time overload multiple; I z Indicates the comprehensive current of the loop; I0 indicates the allowable current.

6. A 35kV substation dual power supply with angle difference loop non-interruptible power supply method according to claim 5, characterized in that: The comprehensive current of the loop is expressed by the following formula: I z =I h +I p Where: I z Indicates the integrated current of the loop; I h Indicates the closed loop current; I p Indicates the load current.

7. A 35kV substation dual power supply with angle difference loop non-stop power supply method according to claim 1, characterized in that: In step 4, the setting of the protection setting only considers the maximum load current allowed by the entire loop.

8. A 35kV substation dual power supply with angle difference loop uninterrupted power supply method according to claim 7, characterized in that: If the protection action conditions are not met, consider avoiding the maximum operating current in the entire loop.

9. A 35kV substation dual power supply with angle difference loop without power failure power switching method according to claim 7, characterized in that: The protection action time is 0-1.2S.

10. A 35kV substation dual power supply with angle difference loop uninterruptible power supply system, running a 35kV substation dual power supply with angle difference loop uninterruptible power supply method as claimed in any one of claims 1 to 9, characterized in that: include: Model building module, data calculation module, result output module; The model building module is used to build a power grid loop diagram model; The data calculation module is used to calculate the closed-loop current, load current, comprehensive current of each line, short-time overload multiple and open-loop setting value; The result output module is used to output protection setting switching signals and closing-loop operation control signals.

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