Small medium-low voltage closed-loop power supply switching method and device, electronic equipment and storage medium

Abstract

The invention relates to the technical field of loop closing to power supply, in particular to a small medium and low voltage loop closing to power supply method and device, electronic equipment and a storage medium, and the method comprises the steps: determining the line condition of a to-be-closed-loop line, obtaining corresponding closed-loop line basic data, determining the voltage difference between the two ends of a loop closing point of the to-be-closed-loop line based on the closed-loop line basic data, and determining the loop closing point of the to-be-closed-loop line. And determining the total current of the circuit to be closed in combination with the total impedance of the circuit to be closed, the load current and the voltage difference between the two ends of the loop closing point, comparing and analyzing the total current of the circuit, and determining whether the loop closing to power supply scheme of the circuit to be closed needs to be modified in combination with the loop closing to power supply rule. According to the method, the total current of the to-be-closed-loop line is compared and analyzed by combining the closed-loop power supply switching rule, the risk point existing in the closed-loop period is evaluated, the closed-loop power supply switching scheme is verified, whether the closed-loop power supply switching scheme needs to be modified or not is determined, and an optimization suggestion is further provided for the closed-loop power supply switching scheme; therefore, the feasibility and the safety of the closed-loop power supply switching scheme are ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of closed-loop power transfer, and provides a small-scale medium and low voltage closed-loop power transfer method, device, electronic device and storage medium. Background Art

[0002] Closed-loop power transfer is a technology that forms a loop network by closing the grid connection switch and transfers the user load without power interruption. By closing the connection switch, the open-loop operation distribution network lines are connected into a loop network, enabling the transfer of load between different power supply points. It can complete line maintenance, fault handling, etc. without power interruption, thus greatly reducing the user power outage time and frequency, improving power supply reliability, and significantly enhancing power supply reliability and user satisfaction.

[0003] Currently, medium and low voltage closed-loop power transfer usually considers whether the closed-loop path crosses multiple electromagnetic loop networks. An electromagnetic loop network refers to a power grid where power grids of different voltage levels are connected together through the transformer electromagnetic circuit. In the scenario of crossing multiple electromagnetic loops or having a 30° angular difference in the "Y-△ transformation", mostly the way of power outage to transfer the load is adopted. When transferring the load during power outage maintenance, fault handling, etc., even when transferring the load during the load trough period, there will inevitably be short-term load losses, thus affecting the user's demand for continuous power supply. Especially with the improvement of the user's requirements for power supply quality, the necessity of using short-term closed-loop power transfer without power interruption becomes more and more prominent. However, the existing technology has not been able to calculate the circulating current during the closed-loop period and evaluate the risk points during the closed-loop period, providing a theoretical basis for whether to transfer the load through short-term power outage. Summary of the Invention

[0004] The present invention provides a small-scale medium and low voltage closed-loop power transfer method, device, electronic device and storage medium, which overcomes the above deficiencies of the existing technology and can effectively solve the problem that the existing technology cannot obtain the circulating current during the closed-loop period for evaluating the risk points during the closed-loop period.

[0005] One of the technical solutions of the present invention is achieved by the following measures: A small-scale medium and low voltage closed-loop power transfer method, including:

[0006] Determine the line conditions of the line to be closed-loop and obtain the corresponding basic data of the closed-loop line, where the basic data of the closed-loop line includes the basic data of line L1 and the basic data of line L2, and the basic data of line L1 and the basic data of line L2 both include active power, reactive power, impedance, bus voltage where it is located, resistance of the line and behind it, reactance of the line and behind it, impedance of the upper-level main transformer, and impedance of the upper-level line;

[0007] Based on the basic data of the closed-loop line, determine the voltage difference at both ends of the closed-loop point of the line to be closed-loop;

[0008]

[0009] Wherein, dU is the voltage difference across the closing point; P1 and P2 are the active powers of lines L1 and L2; Q1 and Q2 are the reactive powers of lines L1 and L2; U L1 is the bus voltage where line L1 is located; U L2 is the bus voltage where line L2 is located; R1 is the resistance of line L1 and its background; R2 is the resistance of line L2 and its background; X1 is the reactance of line L1 and its background; X2 is the reactance of line L2 and its background;

[0010] Based on the total impedance, load current and voltage difference across the closing point of the line to be closed, determine the total current of line L1 and the total current of line L2 in the line to be closed;

[0011] Compare and analyze the total line current, and determine whether it is necessary to modify the closing power transfer scheme of the line to be closed in combination with the closing power transfer rule.

[0012] The following is a further optimization or / and improvement of the above technical solution of the invention:

[0013] The above closing power transfer rule includes:

[0014] If the line condition of the line to be closed is any one of the line to be closed being connected to the same 10 kV bus of the same substation, the line to be closed being connected to the electromagnetic loop network of the same substation operating in split mode, and the electromagnetic loop network formed after the line to be closed is closed passing through a higher voltage level line and equipment, the corresponding closing power transfer rule includes:

[0015] The product of the total current of line L1 and the reliability coefficient and the product of the total current of line L2 and the reliability coefficient are both less than the set value of the third-stage overcurrent of line L1 and the set value of the third-stage overcurrent of line L2, then there is no need for a closing power transfer scheme. Otherwise, the set value modification plan and time shall be clearly defined in the power transfer precautions;

[0016] If the line condition of the line to be closed is that there is a 30° angular difference in the star-delta transformation of the line to be closed, the corresponding closing power transfer rule includes:

[0017] If the total current of line L1 and the total current of line L2 are both greater than the set value of the first-stage overcurrent at 0 s of each line in the line to be closed, then modify the closing power transfer scheme. Otherwise, there is no need for a closing power transfer scheme.

[0018] If the total current of the above line L1 and the total current of line L2 are both greater than the set value of the first-stage overcurrent at 0s in each line of the line to be closed-loop, the closed-loop power supply transfer scheme shall be modified, including temporarily increasing the time difference Δt or temporarily withdrawing the first-stage overcurrent. After the closed-loop is completed, the normal set value shall be restored, and a set of set values less than the set values of all circuit breakers on the lines involved in the closed-loop shall be added at the loop-breaking point, and the operating time shall be set to 0s, and the loop shall be broken by the action of the protection; at the same time, the closed-loop impact current shall be evaluated. If the thermal stability of the conductors L1, L2, L3, and L4 on the closed-loop path is less than the allowable minimum interface S min , the closed-loop shall not be arranged, and a suggestion to reject the closed-loop shall be given to the dispatching and operation specialty.

[0019] Based on the total impedance, load current, and voltage difference at both ends of the loop-breaking point of the line to be closed-loop, determine the total current of line L1 and the total current of line L2 in the line to be closed-loop, including:

[0020] If the line situation of the line to be closed-loop is that the line to be closed-loop is connected to the same 10 kV bus of the same substation, calculate the corresponding circulating current based on the total impedance of the line to be closed-loop and the voltage difference at both ends of the loop-breaking point

[0021]

[0022] If the line situation of the line to be closed-loop is that the line to be closed-loop is connected to the electromagnetic loop network of the same substation operating in split, calculate the corresponding circulating current based on the total impedance of the line to be closed-loop and the voltage difference at both ends of the loop-breaking point

[0023]

[0024] If the line situation of the line to be closed-loop is that the line to be closed-loop forms an electromagnetic loop network passing through higher-voltage-level lines and equipment after closing the loop, calculate the corresponding circulating current based on the total impedance of the line to be closed-loop and the voltage difference at both ends of the loop-breaking point

[0025]

[0026] If the line situation of the line to be closed-loop is that there is a 30° angular difference in the star-delta transformation of the line to be closed-loop, calculate the corresponding circulating current based on the total impedance of the line to be closed-loop and the voltage difference at both ends of the loop-breaking point

[0027]

[0028] Among them, Z L1 is the impedance of line L1; Z L2 is the impedance of line L2; Z T1 is the impedance of the main transformer at the upper level of line L1; Z T2 is the impedance of the main transformer at the upper level of line L2; ZL3 , Z L4 are both the impedance of the upstream line;

[0029] Determine the load current of the line to be closed-loop Add to respectively to obtain the total current of line L1 and the total current of line L2

[0030] The above-mentioned line conditions of the line to be closed-loop include that the line to be closed-loop is connected to the same 10 kV bus of the same substation, the line to be closed-loop is connected to the electromagnetic loop network of the same substation operating in split, the electromagnetic loop network formed after the line to be closed-loop is closed-loop passes through the higher-voltage-level line and equipment, and there is a 30° angular difference in the star-delta transformation of the line to be closed-loop.

[0031] The second technical solution of the present invention is achieved by the following measures: A small-scale medium and low voltage closed-loop power transfer device, including:

[0032] A data acquisition unit determines the line conditions of the line to be closed-loop and obtains the corresponding basic data of the closed-loop line, where the basic data of the closed-loop line includes the basic data of line L1 and the basic data of line L2, and the basic data of line L1 and the basic data of line L2 both include active power, reactive power, impedance, the bus voltage where it is located, the resistance of the line and behind it, the reactance of the line and behind it, the impedance of the upstream main transformer, and the impedance of the upstream line;

[0033] A pressure difference determination unit determines the pressure difference at both ends of the closed-loop point of the line to be closed-loop based on the basic data of the closed-loop line;

[0034]

[0035] Among them, dU is the pressure difference at both ends of the closed-loop point; P1 and P2 are the active powers of lines L1 and L2; Q1 and Q2 are the reactive powers of lines L1 and L2; U L1 is the bus voltage where line L1 is located; U L2 is the bus voltage where line L2 is located; R1 is the resistance of line L1 and behind it; R2 is the resistance of line L2 and behind it; X1 is the reactance of line L1 and behind it; X2 is the reactance of line L2 and behind it;

[0036] A line current analysis unit determines the total current of line L1 and the total current of line L2 in the line to be closed-loop by combining the total impedance, load current and pressure difference at both ends of the closed-loop point of the line to be closed-loop;

[0037] A modification analysis unit compares and analyzes the total line current and determines whether it is necessary to modify the closed-loop power transfer scheme of the line to be closed-loop in combination with the closed-loop power transfer rules.

[0038] The following is a further optimization and / or improvement of the above-mentioned invention technical solution:

[0039] The above line current analysis unit includes:

[0040] The circulating current calculation module includes:

[0041] If the line condition of the line to be closed-loop is that the line to be closed-loop is connected to the same 10 kV busbar of the same substation, calculate the corresponding circulating current based on the total impedance of the line to be closed-loop and the voltage difference at both ends of the closed-loop point.

[0042]

[0043] If the line condition of the line to be closed-loop is that the line to be closed-loop is connected to the electromagnetic loop network of the same substation operating in split operation, calculate the corresponding circulating current based on the total impedance of the line to be closed-loop and the voltage difference at both ends of the closed-loop point.

[0044]

[0045] If the line condition of the line to be closed-loop is that the closed-loop line forms an electromagnetic loop network passing through higher-voltage-level lines and equipment after closing the loop, calculate the corresponding circulating current based on the total impedance of the line to be closed-loop and the voltage difference at both ends of the closed-loop point.

[0046]

[0047] If the line condition of the line to be closed-loop is that there is a 30° angular difference in the star-delta transformation of the line to be closed-loop, calculate the corresponding circulating current based on the total impedance of the line to be closed-loop and the voltage difference at both ends of the closed-loop point.

[0048]

[0049] Among them, Z L1 is the impedance of line L1; Z L2 is the impedance of line L2; Z T1 is the impedance of the main transformer at the upper level of line L1; Z T2 is the impedance of the main transformer at the upper level of line L2; Z L3 and Z L4 are both the impedances of the upper-level lines;

[0050] The total current determination module determines the load current of the line to be closed-loop. Add respectively to to obtain the total current of line L1 and the total current of line L2

[0051] The above-mentioned modification analysis unit includes:

[0052] A loop closing power transfer rule acquisition module that acquires loop closing power transfer rules, where the loop closing power transfer rules include:

[0053] If the line condition of the line to be looped is any one of the following: the line to be looped is connected to the same 10 kV bus of the same substation, the line to be looped is connected to the electromagnetic loop network of the same substation operating in split mode, or the electromagnetic loop network formed after the line to be looped is closed passes through a higher voltage level line and equipment, the corresponding loop closing power transfer rules include:

[0054] If the product of the total current of line L1 and the reliability coefficient and the product of the total current of line L2 and the reliability coefficient are both less than the overcurrent stage III setting value of line L1 and the overcurrent stage III setting value of line L2, then no loop closing power transfer plan is required; otherwise, the setting value modification plan and time shall be clearly defined in the power transfer precautions.

[0055] If the line condition of the line to be looped is that there is a 30° angular difference in the star-delta transformation of the line to be looped, the corresponding loop closing power transfer rules include:

[0056] If the total current of line L1 and the total current of line L2 are both greater than the overcurrent stage I setting value at 0 s of each line in the line to be looped, then modify the loop closing power transfer plan; otherwise, no loop closing power transfer plan is required.

[0057] An analysis and determination module that compares and analyzes the total line current and determines whether it is necessary to modify the loop closing power transfer plan of the line to be looped in combination with the loop closing power transfer rules.

[0058] The third technical solution of the present invention is achieved by the following measures: An electronic device includes a processor and a memory, and a computer program is stored in the memory. The computer program is loaded and executed by the processor to implement the steps in the small and medium voltage loop closing power transfer method.

[0059] The fourth technical solution of the present invention is achieved by the following measures: A storage medium stores a computer program readable by a computer, and the computer program is set to execute the steps in the small and medium voltage loop closing power transfer method when running.

[0060] Based on the line condition of the line to be looped, the present invention analyzes the voltage difference at both ends of the loop closing point of the line to be looped, the loop current and the total current of the line, compares and analyzes the total current of the line in combination with the loop closing power transfer rules, evaluates the risk points during loop closing, verifies the loop closing power transfer plan, determines whether it is necessary to modify the loop closing power transfer plan, and further provides optimization suggestions for the loop closing power transfer plan, thereby ensuring the feasibility and safety of the loop closing power transfer plan. Description of the Drawings

[0061] Appendix Figure 1 Schematic diagram of the process for the small - scale medium - and low - voltage closed - loop power transfer method provided by the present invention.

[0062] Appendix Figure 2 Schematic wiring diagram of the loop - closing line to be connected to the same 10 - kV busbar of the same substation provided by the present invention.

[0063] Appendix Figure 3 Schematic wiring diagram of the loop - closing line to be connected to the electromagnetic loop network of the same substation operating in split - bus mode provided by the present invention.

[0064] Appendix Figure 4 Schematic wiring diagram of the loop - closing line provided by the present invention, where the loop - closing line forms an electromagnetic loop network after loop - closing and passes through a higher - voltage - level line and equipment.

[0065] Appendix Figure 5 Schematic wiring diagram of the loop - closing line provided by the present invention, where there is a 30° angular difference in the star - delta transformation of the loop - closing line.

[0066] Appendix Figure 6 Schematic diagram of the structure of the small - scale medium - and low - voltage closed - loop power transfer device provided by the present invention. Detailed implementation manners

[0067] The present invention is not limited by the following embodiments, and the specific implementation manners can be determined according to the technical solutions of the present invention and the actual situation.

[0068] Those skilled in the art of the present technology can understand that, unless specifically stated, in the embodiments of the present invention, a "module" or "unit" refers to a computer program with a predetermined function or a part of a computer program, which works together with other relevant parts to achieve a predetermined goal, and can be implemented in whole or in part by using software, hardware (such as a processing circuit or a memory), or a combination thereof. Similarly, a processor (or multiple processors or memories) can be used to implement one or more modules or units. In addition, each module or unit can be a part of an overall module or unit that includes the function of that module or unit.

[0069] In addition, in the embodiments of the present invention, "a plurality of" refers to two or more, and "first" and "second" are used for distinguishing descriptions and should not be understood as implying relative importance.

[0070] The embodiments of the present invention provide a small - scale medium - and low - voltage closed - loop power transfer method, device, electronic device, and storage medium. The small - scale medium - and low - voltage closed - loop power transfer device can be integrated in a computer device, which can be a server or a terminal device, etc.; it can also be jointly executed by a terminal and a server. The above examples should not be construed as limitations on the present invention.

[0071] The above-mentioned terminal may include a mobile phone, a wearable intelligent device, a tablet computer, a laptop computer, a personal computer (PC), a vehicle-mounted computer, etc., and the present invention does not limit this. The present invention does not limit the number of terminal devices.

[0072] The above-mentioned server may be an independent physical server, or a server cluster or distributed system composed of multiple physical servers, or a cloud server providing basic cloud computing services such as cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communications, middleware services, domain name services, security services, CDN, and big data and artificial intelligence platforms. The present invention does not limit this.

[0073] For example, the computer device determines the line conditions of the to-be-closed-loop line, obtains the corresponding basic data of the closed-loop line, and determines the voltage difference at both ends of the closed-loop point of the to-be-closed-loop line based on the basic data of the closed-loop line; combines the total impedance, load current, and voltage difference at both ends of the closed-loop point of the to-be-closed-loop line to determine the circulating current, the total current of line L1, and the total current of line L2 in the to-be-closed-loop line; compares and analyzes the total line current, and combines the closed-loop power transfer rule to determine whether it is necessary to modify the closed-loop power transfer scheme of the to-be-closed-loop line. Thereby, the risk points during the closed-loop are evaluated, the closed-loop power transfer scheme is verified, it is determined whether it is necessary to modify the closed-loop power transfer scheme, and further optimization suggestions are provided for the closed-loop power transfer scheme, thus ensuring the feasibility and safety of the closed-loop power transfer scheme.

[0074] Based on this, the technical solutions of the present invention will be introduced and described below in combination with several examples.

[0075] Example 1: As shown in the appendix Figure 1 The embodiment of the present invention discloses a small-scale medium and low voltage closed-loop power transfer method, including:

[0076] Step S110, determine the line conditions of the to-be-closed-loop line, and obtain the corresponding basic data of the closed-loop line, where the basic data of the closed-loop line includes the basic data of line L1 and the basic data of line L2, and the basic data of line L1 and the basic data of line L2 both include active power, reactive power, impedance, bus voltage where it is located, resistance of the line and behind it, reactance of the line and behind it, impedance of the upper-level main transformer, and impedance of the upper-level line;

[0077] Step S120, determine the voltage difference at both ends of the closed-loop point of the to-be-closed-loop line based on the basic data of the closed-loop line;

[0078]

[0079] Among them, dU is the voltage difference at both ends of the closed-loop point; P1 and P2 are the active powers of line L1 and line L2; Q1 and Q2 are the reactive powers of line L1 and line L2; UL1 is the bus voltage where line L1 is located; U L2 is the bus voltage where line L2 is located; R1 is the resistance of line L1 and behind it; R2 is the resistance of line L2 and behind it; X1 is the reactance of line L1 and behind it; X2 is the reactance of line L2 and behind it;

[0080] Step S130, based on the total impedance, load current, and voltage difference at both ends of the closing point of the line to be closed-loop, determine the total current of line L1 and the total current of line L2 in the line to be closed-loop;

[0081] Step S140, compare and analyze the total line current, and determine whether it is necessary to modify the closing-loop power transfer scheme of the line to be closed-loop in combination with the closing-loop power transfer rule.

[0082] In this embodiment, in step 110, determine the line conditions of the line to be closed-loop and obtain the corresponding basic data of the closed-loop line. The line conditions of the line to be closed-loop include that the line to be closed-loop is connected to the same 10 kV bus of the same substation, the line to be closed-loop is connected to the electromagnetic loop network of the same substation operating in split, the closed-loop line forms an electromagnetic loop network after closing through a higher-voltage-level line and equipment, and there is a 30° angular difference in the star-delta transformation of the line to be closed-loop.

[0083] As shown in the appendix Figure 2 shown, the line condition of the line to be closed-loop with this wiring structure is that the line to be closed-loop is connected to the same 10 kV bus of the same substation, and obtain the active power P1, reactive power Q1, impedance Z of its line L1 L1 , the bus voltage U where it is located L1 , the resistance R1 of line L1 and behind it, the reactance X1 of the line and behind it, the impedance of the upper-level main transformer, the impedance of the upper-level line, the active power P2, reactive power Q2, impedance Z of line L2 L2 , the bus voltage U where it is located L2 , the resistance R2 of line L2 and behind it, the reactance X2 of the line and behind it, the impedance Z of the upper-level main transformer T1 , the impedance Z of the upper-level line T2 .

[0084] As shown in the appendix Figure 3 shown, the line condition of the line to be closed-loop with this wiring structure is that the line to be closed-loop is connected to the electromagnetic loop network of the same substation operating in split, and obtain the active power P1, reactive power Q1, impedance Z of its line L1 L1 , the bus voltage U where it is located L1 , the resistance R1 of line L1 and behind it, the reactance X1 of the line and behind it, the impedance of the upper-level main transformer, the impedance of the upper-level line, the active power P2, reactive power Q2, impedance Z of line L2 L2 , the bus voltage U where it is located L2, line L2 and the resistor R2 behind it, the line and the reactance X2 behind it, the impedance Z of the upper main transformer T1 , the impedance Z of the upper line T2 .

[0085] As shown in the appendix Figure 4 , for the line condition of the loop - closing line of this wiring structure, after the loop - closing of the loop - closing line, an electromagnetic loop network is formed through the higher - voltage - level line and equipment. Obtain the active power P1, reactive power Q1, and impedance Z of line L1 L1 , the bus voltage U where it is located L1 , line L1 and the resistor R1 behind it, the line and the reactance X1 behind it, the upper main transformer impedance, the upper line impedance, the active power P2, reactive power Q2, and impedance Z of line L2 L2 , the bus voltage U where it is located L2 , line L2 and the resistor R2 behind it, the line and the reactance X2 behind it, the impedance Z of the upper main transformer T1 , the impedance Z of the upper line T2 , and the impedance Z of the upper line L3 , Z L4 .

[0086] As shown in the appendix Figure 5 , for the line condition of the loop - closing line of this wiring structure, there is a 30° angular difference in the "Y - △" star - delta transformation for the loop - closing line. Obtain the active power P1, reactive power Q1, and impedance Z of line L1 L1 , the bus voltage U where it is located L1 , line L1 and the resistor R1 behind it, the line and the reactance X1 behind it, the upper main transformer impedance, the upper line impedance, the active power P2, reactive power Q2, and impedance Z of line L2 L2 , the bus voltage U where it is located L2 , line L2 and the resistor R2 behind it, the line and the reactance X2 behind it, the impedance Z of the upper main transformer T1 , the impedance Z of the upper line T2 , and the impedance Z of the upper line L3 , Z L4 .

[0087] The acquisition of the above - mentioned basic data of each loop - closing line is a well - known existing technology, where:

[0088] Reduce the equivalent impedance of the upper main transformer to the voltage level where the loop - closing line is located, specifically as follows:

[0089]

[0090] Z T = R T + jX T

[0091] Among them, R T is the main transformer resistance; X T is the main transformer reactance; P k is the short-circuit loss of the main transformer; U N is the rated voltage of the main transformer at the voltage level where the line to be looped is located; U k % is the short-circuit impedance of the main transformer; S N is the rated capacity of the main transformer.

[0092] The impedance of the upstream line also needs to be reduced to the voltage level where the looped line is located, specifically as follows:

[0093]

[0094] Z L = R1 + jX′1

[0095] Among them, R′ l is the reduced line resistance; X′ l is the reduced line reactance; k is the main transformer turns ratio; R1 is the nominal value of the line reactance; X1 is the nominal value of the line reactance; r1 is the nominal value of the line impedance per kilometer; x1 is the nominal value of the line impedance per kilometer; l is the length of the looped line.

[0096] The present invention discloses a small-scale medium and low voltage loop transfer power supply method, which analyzes the voltage difference at both ends of the loop point of the line to be looped and the total current of the line to be looped based on the line conditions of the line to be looped, and compares and analyzes the total current of the line to be looped in combination with the loop transfer power supply rules to determine whether it is necessary to modify the loop transfer power supply scheme of the line to be looped; thereby evaluating the risk points existing during the loop, verifying the loop transfer power supply scheme, determining whether it is necessary to modify the loop transfer power supply scheme, and further providing optimization suggestions for the loop transfer power supply scheme, so as to ensure the feasibility and safety of the loop transfer power supply scheme.

[0097] Embodiment 2: The embodiment of the present invention is a further optimization of the above embodiment, in which the total current of line L1 and the total current of line L2 in the line to be looped are determined by combining the total impedance, load current and voltage difference at both ends of the loop point of the line to be looped, including:

[0098] Step S210, if the line condition of the line to be looped is that the line to be looped is connected to the same 10 kV bus of the same substation, calculate the corresponding circulating current based on the total impedance of the line to be looped and the voltage difference at both ends of the loop point

[0099]

[0100] Here, let the bus voltages where the line to be looped is located be U1∠0° and U2∠0° respectively, and ignore the phase angle difference of the bus voltages, and establish the above loop equation.

[0101] If the line condition of the line to be closed-loop is that the line to be closed-loop is connected to the electromagnetic loop network of the same substation that is split and operated, based on the total impedance of the line to be closed-loop and the voltage difference across the closed-loop point, calculate the corresponding circulating current

[0102]

[0103] Here, let the bus voltages where the line to be closed-loop is located be U1∠0° and U2∠0° respectively. Ignoring the phase angle difference of the bus voltages here, establish the above loop equation.

[0104] If the line condition of the line to be closed-loop is that after the line to be closed-loop is closed-loop, an electromagnetic loop network is formed through higher-voltage-level lines and equipment, based on the total impedance of the line to be closed-loop and the voltage difference across the closed-loop point, calculate the corresponding circulating current

[0105]

[0106] Here, the total impedance needs to consider the sum of the impedance of the upper-level main transformer and the impedance of the closed-loop line, and thus establish the above loop equation.

[0107] If the line condition of the line to be closed-loop is that there is a 30° angle difference in the star-delta transformation for the line to be closed-loop, based on the total impedance of the line to be closed-loop and the voltage difference across the closed-loop point, calculate the corresponding circulating current

[0108]

[0109] Here, the different voltage phases need to be considered. Let the bus voltages where the closed-loop line is located be U1∠0° and U2∠30° respectively. The total impedance needs to consider the sum of the upper-level main transformer, line impedance, and the impedance of the closed-loop line, and thus establish the above loop equation.

[0110] Among them, Z L1 is the impedance of line L1; Z L2 is the impedance of line L2; Z T1 is the impedance of the upper-level main transformer of line L1; Z T2 is the impedance of the upper-level main transformer of line L2; Z L3 and Z L4 are both the impedances of the upper-level lines;

[0111] Step S220, determine the load current of the line to be closed-loop Add to respectively to obtain the total current of line L1 and the total current of line L2

[0112] Embodiment 3: The embodiment of the present invention further optimizes the above embodiments, and the closed-loop power transfer rules include:

[0113] (1) If the line conditions of the line to be closed-loop are any one of the following: the line to be closed-loop is connected to the same 10 kV bus of the same substation, the line to be closed-loop is connected to the electromagnetic loop network of the same substation operating in split mode, or the closed-loop of the line to be closed-loop forms an electromagnetic loop network passing through a higher-voltage-level line and equipment, the corresponding closed-loop power transfer rules include:

[0114] Total current of line L1 Multiplied by the reliability coefficient, and the total current of line L2 Multiplied by the reliability coefficient are both less than the overcurrent stage III setting value of line L1 and the overcurrent stage III setting value of line L2, then there is no need for a closed-loop power transfer plan. Otherwise, the setting value modification plan and time need to be clearly defined in the power transfer precautions.

[0115] The above reliability coefficient is set as needed and can be taken as 1.3.

[0116] If the closed-loop power transfer plan needs to be modified, the setting value modification plan and time need to be clearly defined in the power transfer precautions, and when modifying, consider the maximum current and duration borne by the loop network lines after the power flow transfer under the N-1 condition to check whether the thermal effect of the conductor exceeds the allowable value.

[0117] (2) If the line conditions of the line to be closed-loop are that there is a 30° angular difference in the star-delta transformation of the line to be closed-loop, the corresponding closed-loop power transfer rules include:

[0118] Total current of line L1 And the total current of line L2 Are both greater than the overcurrent stage I setting value at 0 s of each line in the line to be closed-loop, then modify the closed-loop power transfer plan. Otherwise, there is no need for a closed-loop power transfer plan. Modifying the closed-loop power transfer plan includes temporarily increasing the time difference Δt or temporarily withdrawing the overcurrent stage I. After the closed-loop is completed, restore the normal setting value, and add a set of setting values less than the setting values of all circuit breakers on the closed-loop-related lines at the loop-breaking point, with the action time set to 0 s, and use the protection action method to break the loop; at the same time, the closed-loop impact current should be evaluated. If the thermal stability of conductors L1, L2, L3, and L4 on the closed-loop path is less than the allowable minimum cross-section S min , then the closed-loop is not allowed to be arranged, and a suggestion of rejecting the closed-loop is given to the dispatching and operation specialty.

[0119] During this process, it is also possible to consider the maximum current and duration borne by the loop network lines after the power flow transfer under the N-1 condition to check whether the thermal effect of the conductor exceeds the allowable value.

[0120] The thermal effect Q of the above conductor t = Q z + Qf , where the periodic component is calculated according to Q z =I 2 , and the aperiodic component is calculated according to Q f =0.05I 2 . The minimum interface allowed by the thermal stability of the conductor is calculated according to . Check whether the conductor cross-section meets the requirements. If not, it is not allowed to arrange load transfer through closing the loop.

[0121] Embodiment 4: If it is determined that the line condition of the line to be closed-loop is that the line to be closed-loop is connected to the electromagnetic loop network of the same substation in split operation, then obtain the total current of line L1 and the total current of line L2 . Compare and analyze the total line current, and determine whether it is necessary to modify the closed-loop power transfer scheme of the line to be closed-loop in combination with the closed-loop power transfer rules, specifically including:

[0122] Assume that the conductor type of line L1 is LGJ-120, the length is 15 km, the head-end voltage is 10.2 kV, the end power S = 2.5 + j1 MW, and it is connected to the No. 1 6.3 MVA main transformer. The short-circuit loss P of the No. 1 main transformer k = 32.6 kW, the short-circuit impedance is U k % = 7.06%, the impedance per kilometer of the line is r1 = 0.27 Ω / km, and the reactance per kilometer of the line is X1 = 0.335 Ω / km; the conductor type of line L2 is LGJ-240, the length is 10 km, the head-end voltage is 10.5 kV, the end power S = 3 + j1 MW, and it is connected to the No. 2 10 MVA main transformer. The short-circuit loss P of the No. 2 main transformer k = 42.8 kW, the short-circuit impedance is U k % = 7.37%, the impedance per kilometer of the line is r1 = 0.105 Ω / km, and the reactance per kilometer of the line is X1 = 0.088 Ω / km. The calculation process is as follows:

[0123]

[0124] Z T1 = R T1 + jX T1 = 0.09 + j1.2355

[0125]

[0126] Z l1 = R l1 + jX l1 = 4.05 + 5.025

[0127]

[0128] Z T2= R T2 + jX T2 = 0.047 + j0.8125

[0129]

[0130] Z l2 = R l2 + jX l2 = 1.05 + j0.88

[0131]

[0132] The voltage difference across both ends of the loop point of the loop - closing line is as follows, and the corresponding circulating current

[0133]

[0134] Determine the load current of the loop - closing line Add to respectively, to obtain the total current of line L1 and the total current of line L2

[0135]

[0136] Example 5: As shown in the appendix Figure 6 This embodiment of the present invention discloses a small - sized medium - and low - voltage loop - closing power transfer device, including:

[0137] A data acquisition unit determines the line conditions of the loop - closing line and obtains the corresponding basic data of the loop - closing line. The basic data of the loop - closing line includes the basic data of line L1 and the basic data of line L2. The basic data of line L1 and the basic data of line L2 both include active power, reactive power, impedance, the voltage of the bus where the line is located, the resistance of the line and its background, the reactance of the line and its background, the impedance of the upper - level main transformer, and the impedance of the upper - level line;

[0138] A voltage - difference determination unit determines the voltage difference across both ends of the loop point of the loop - closing line based on the basic data of the loop - closing line;

[0139]

[0140] where dU is the voltage difference across both ends of the loop point; P1 and P2 are the active powers of lines L1 and L2; Q1 and Q2 are the reactive powers of lines L1 and L2; U L1 is the voltage of the bus where line L1 is located; U L2is the bus voltage where line L2 is located; R1 is the resistance of line L1 and the resistance behind it; R2 is the resistance of line L2 and the resistance behind it; X1 is the reactance of line L1 and the reactance behind it; X2 is the reactance of line L2 and the reactance behind it;

[0141] The line current analysis unit determines the total current of line L1 and the total current of line L2 in the to-be-closed-loop line by combining the total impedance, load current, and voltage difference across both ends of the closing point of the to-be-closed-loop line;

[0142] The modification analysis unit compares and analyzes the total line current and determines whether it is necessary to modify the closing and power transfer scheme of the to-be-closed-loop line in combination with the closing and power transfer rules.

[0143] Among them, the line current analysis unit includes:

[0144] The circulating current calculation module includes:

[0145] If the line condition of the to-be-closed-loop line is that the to-be-closed-loop line is connected to the same 10 kV bus of the same substation, calculate the corresponding circulating current based on the total impedance of the to-be-closed-loop line and the voltage difference across both ends of the closing point

[0146]

[0147] If the line condition of the to-be-closed-loop line is that the to-be-closed-loop line is connected to the electromagnetic loop network of the same substation operating in split mode, calculate the corresponding circulating current based on the total impedance of the to-be-closed-loop line and the voltage difference across both ends of the closing point

[0148]

[0149] If the line condition of the to-be-closed-loop line is that the to-be-closed-loop line forms an electromagnetic loop network passing through higher-voltage-level lines and equipment after closing, calculate the corresponding circulating current based on the total impedance of the to-be-closed-loop line and the voltage difference across both ends of the closing point

[0150]

[0151] If the line condition of the to-be-closed-loop line is that there is a 30° angular difference in the star-delta transformation for the to-be-closed-loop line, calculate the corresponding circulating current based on the total impedance of the to-be-closed-loop line and the voltage difference across both ends of the closing point

[0152]

[0153] Among them, Z L1 is the impedance of line L1; Z L2 is the impedance of line L2; Z T1 is the impedance of the main transformer at the upper level of line L1; Z T2 is the impedance of the main transformer at the upper level of line L2; ZL3 , Z L4 are both the impedance of the upstream line;

[0154] The total current determination module determines the load current of the line to be closed-loop Add respectively to to obtain the total current of line L1 and the total current I of line L2 ∑2 .

[0155] Among them, the modification analysis unit includes:

[0156] The closed-loop power transfer rule acquisition module acquires the closed-loop power transfer rule, and the closed-loop power transfer rule includes:

[0157] If the line condition of the line to be closed-loop is any one of the line to be closed-loop is connected to the same 10 kV bus of the same substation, the line to be closed-loop is connected to the electromagnetic loop network of the same substation operating in split operation, and the electromagnetic loop network formed after the line to be closed-loop is closed-loop passes through a higher voltage level line and equipment, the corresponding closed-loop power transfer rule includes:

[0158] The product of the total current of line L1 and the reliability coefficient and the product of the total current of line L2 and the reliability coefficient are both less than the overcurrent section III setting value of line L1 and the overcurrent section III setting value of line L2, then there is no need for a closed-loop power transfer plan. Otherwise, the setting value modification plan and time shall be clearly defined in the power transfer precautions;

[0159] If the line condition of the line to be closed-loop is that there is a 30° angular difference in the star-delta transformation of the line to be closed-loop, the corresponding closed-loop power transfer rule includes:

[0160] If the total current of line L1 and the total current of line L2 are both greater than the overcurrent section I setting value of 0 s in each line of the line to be closed-loop, the closed-loop power transfer plan is modified. Otherwise, there is no need for a closed-loop power transfer plan;

[0161] The analysis and determination module compares and analyzes the total line current, and determines whether it is necessary to modify the closed-loop power transfer plan of the line to be closed-loop in combination with the closed-loop power transfer rule.

[0162] Embodiment 6: An embodiment of the present invention discloses a storage medium, on which a computer program readable by a computer is stored, and the computer program is set to execute a small and medium voltage closed-loop power transfer method when running.

[0163] The above storage medium may include, but is not limited to: various media such as USB flash drives, read-only memories, mobile hard disks, magnetic disks or optical discs that can store computer programs.

[0164] Embodiment 7: An embodiment of the present invention discloses an electronic device, including a processor and a memory. A computer program is stored in the memory and is loaded and executed by the processor to implement a small and medium voltage closed-loop power transfer method.

[0165] The above-mentioned processor may be a central processing unit (CPU), a general-purpose processor, a digital signal processor (DSP), an ASIC, an FPGA or other programmable logic devices, transistor logic devices, hardware components or any combination thereof. It can implement or execute various exemplary logical blocks, modules and circuits described in connection with the disclosure of the present invention. It can also be a combination that realizes computing functions, such as a combination including one or more microprocessors, a combination of DSP and a microprocessor, and so on. The memory may include, but is not limited to: various media that can store computer programs, such as USB flash drives, read-only memories, mobile hard disks, magnetic disks or optical discs.

[0166] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memories, CD-ROMs, optical memories, etc.) containing computer-usable program code. The solutions in the embodiments of the present invention can be implemented in various computer languages. For example, object-oriented programming languages such as Java and interpreted scripting languages such as JavaScript.

[0167] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, and the combination of processes and / or blocks in the flowchart and / or block diagram, can be realized by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate means for realizing the functions specified in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0168] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing devices to work in a specific manner, so that the instructions stored in the computer-readable memory generate a manufactured article including instruction means, and the instruction means realizes the functions specified in Figure 1 one process or multiple processes and / or blocks Figure 1The functions specified in one or more boxes.

[0169] The above content is only a specific implementation manner of the present invention, which has strong adaptability and implementation effects. However, the protection scope of the present invention is not limited thereto. Any person skilled in the art in the technical field disclosed by the present invention can easily think of changes or substitutions, which should be covered within the protection scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention still fall within the scope covered by the present invention.

Claims

1. A small-scale medium and low voltage loop closing power transfer method, characterized in that, Including: Determine the line conditions of the line to be closed-loop, and obtain the corresponding basic data of the closed-loop line. The basic data of the closed-loop line includes the basic data of line L1 and the basic data of line L2. The basic data of line L1 and the basic data of line L2 both include active power, reactive power, impedance, bus voltage where it is located, resistance of the line and behind it, reactance of the line and behind it, impedance of the upper-level main transformer, and impedance of the upper-level line; Based on the basic data of the closed-loop line, determine the voltage difference between the two ends of the closed-loop point of the line to be closed-loop; Among them, dU is the voltage difference across the closing point; P1 and P2 are the active powers of lines L1 and L2; Q1 and Q2 are the reactive powers of lines L1 and L2; U L1 is the bus voltage where line L1 is located; U L2 is the bus voltage where line L2 is located; R1 is the resistance of line L1 and its background; R2 is the resistance of line L2 and its background; X1 is the reactance of line L1 and its background; X2 is the reactance of line L2 and its background; Combined with the total impedance, load current, and voltage difference between the two ends of the closed-loop point of the line to be closed-loop, determine the total current of line L1 and the total current of line L2 in the line to be closed-loop; Compare and analyze the total line current, and determine whether it is necessary to modify the closed-loop power transfer scheme of the line to be closed-loop in combination with the closed-loop power transfer rules.

2. The small-scale medium and low voltage closed-loop power transfer method according to claim 1, characterized in that The closed-loop power transfer rules include: If the line condition of the line to be closed-loop is any one of the line to be closed-loop is connected to the same 10 kV bus of the same substation, the line to be closed-loop is connected to the electromagnetic loop network of the same substation operating in split, and the electromagnetic loop network is formed after the line to be closed-loop is closed-loop and passes through a higher-voltage-level line and equipment, the corresponding closed-loop power transfer rules include: If the product of the total current of line L1 and the reliability coefficient and the product of the total current of line L2 and the reliability coefficient are both less than the setting value of the third-stage overcurrent of line L1 and the setting value of the third-stage overcurrent of line L2, there is no need for a closed-loop power transfer scheme. Otherwise, the setting value modification plan and time shall be clearly defined in the power transfer precautions; If the line condition of the line to be closed-loop is that there is a 30° angle difference in the star-delta transformation of the line to be closed-loop, the corresponding closed-loop power transfer rules include: If the total current of line L1 and the total current of line L2 are both greater than the setting value of the first-stage overcurrent at 0 s of each line in the line to be closed-loop, modify the closed-loop power transfer scheme. Otherwise, there is no need for a closed-loop power transfer scheme.

3. The small-scale medium-low voltage closed-loop power transfer method according to claim 2, characterized in that, If the total current of line L1 and the total current of line L2 are both greater than the instantaneous overcurrent stage I setting value at 0s in each line of the loop-closing line, the loop-closing power transfer scheme shall be modified, including temporarily increasing the time difference Δt or temporarily withdrawing the instantaneous overcurrent stage I. After the loop closing is completed, the normal setting value shall be restored. A set of setting values less than the setting values of all circuit breakers on the loop-closing related lines shall be added at the loop-opening point, and the operating time shall be set to 0s. The loop-opening shall be carried out by means of protection operation. At the same time, the loop-closing impact current shall be evaluated. If the thermal stability of conductors L1, L2, L3, and L4 on the loop-closing path is less than the allowable minimum cross-section S min , loop closing is not allowed, and suggestions for rejecting loop closing shall be given to the dispatching and operation specialty.

4. The small-scale medium and low voltage closed-loop power transfer method according to any one of claims 1 to 3, characterized in that The step of combining the total impedance, load current, and voltage difference between the two ends of the closed-loop point of the line to be closed-loop to determine the total current of line L1 and the total current of line L2 in the line to be closed-loop includes: If the line condition of the line to be closed-loop is that the line to be closed-loop is connected to the same 10 kV busbar of the same substation, calculate the corresponding circulating current based on the total impedance of the line to be closed-loop and the voltage difference at both ends of the closed-loop point. If the line condition of the line to be closed-loop is that the line to be closed-loop is connected to the electromagnetic loop network of the same substation with split operation, calculate the corresponding circulating current based on the total impedance of the line to be closed-loop and the voltage difference at both ends of the closed-loop point. If the line condition of the line to be closed-loop forms an electromagnetic loop network through higher-voltage-level lines and equipment after closing the loop, calculate the corresponding circulating current based on the total impedance of the line to be closed-loop and the voltage difference across both ends of the loop point. If the line condition of the line to be closed-loop is that there is a 30° angular difference in the star-delta transformation for the line to be closed-loop, calculate the corresponding circulating current based on the total impedance of the line to be closed-loop and the voltage difference across both ends of the closed-loop point. Among them, Z L1 is the impedance of line L1; Z L2 is the impedance of line L2; Z T1 is the impedance of the main transformer at the upper level of line L1; Z T2 is the impedance of the main transformer at the upper level of line L2; Z L3 and Z L4 are both the impedances of the upper-level lines; Determine the load current of the circuit to be closed Add to respectively to obtain the total current of line L1 and the total current of line L2 5. The small-scale medium and low voltage closed-loop power transfer method according to any one of claims 1 to 4, characterized in that The line conditions of the line to be closed-loop include that the line to be closed-loop is connected to the same 10 kV bus of the same substation, the line to be closed-loop is connected to the electromagnetic loop network of the same substation operating in split, the electromagnetic loop network is formed after the line to be closed-loop is closed-loop and passes through a higher-voltage-level line and equipment, and there is a 30° angle difference in the star-delta transformation of the line to be closed-loop.

6. A small medium - low voltage closed - loop power transfer device using the method according to any one of claims 1 to 5, characterized in that, Including: A data acquisition unit that determines the line conditions of the line to be closed-loop and obtains the corresponding basic data of the closed-loop line. The basic data of the closed-loop line includes the basic data of line L1 and the basic data of line L2. The basic data of line L1 and the basic data of line L2 both include active power, reactive power, impedance, bus voltage where it is located, resistance of the line and behind it, reactance of the line and behind it, impedance of the upper-level main transformer, and impedance of the upper-level line; A voltage difference determination unit that determines the voltage difference between the two ends of the closed-loop point of the line to be closed-loop based on the basic data of the closed-loop line; Among them, dU is the voltage difference across the loop closing point; P1 and P2 are the active powers of lines L1 and L2; Q1 and Q2 are the reactive powers of lines L1 and L2; U L1 is the bus voltage where line L1 is located; U L2 is the bus voltage where line L2 is located; R1 is the resistance of line L1 and its background; R2 is the resistance of line L2 and its background; X1 is the reactance of line L1 and its background; X2 is the reactance of line L2 and its background; A line current analysis unit that combines the total impedance, load current, and voltage difference between the two ends of the closed-loop point of the line to be closed-loop to determine the total current of line L1 and the total current of line L2 in the line to be closed-loop; Modify the analysis unit to compare and analyze the total line current, and determine whether it is necessary to modify the power transfer scheme of the line to be looped according to the loop closing and power transfer rules.

7. The small medium and low voltage closed-loop power transfer device according to claim 6, characterized in that The line current analysis unit includes: The circulating current calculation module includes: If the line condition of the line to be closed-loop is that the line to be closed-loop is connected to the same 10 kV busbar of the same substation, calculate the corresponding circulating current based on the total impedance of the line to be closed-loop and the voltage difference at both ends of the closed-loop point. If the line condition of the line to be closed-loop is that the line to be closed-loop is connected to the electromagnetic loop network of the same substation that is running in split operation, calculate the corresponding circulating current based on the total impedance of the line to be closed-loop and the voltage difference at both ends of the closed-loop point. If the line condition of the line to be closed-loop is that an electromagnetic loop network is formed after the line to be closed-loop is closed-loop through a higher-voltage-level line and equipment, calculate the corresponding circulating current based on the total impedance of the line to be closed-loop and the voltage difference at both ends of the closed-loop point. If the line condition of the line to be closed-loop is that there is a 30° angular difference in the star-delta transformation for the line to be closed-loop, calculate the corresponding circulating current based on the total impedance of the line to be closed-loop and the voltage difference across both ends of the closed-loop point. Among them, Z L1 is the impedance of line L1; Z L2 is the impedance of line L2; Z T1 is the impedance of the main transformer at the upper level of line L1; Z T2 is the impedance of the main transformer at the upper level of line L2; Z L3 and Z L4 are both the impedances of the upper-level lines; The total current determination module determines the load current of the line to be closed-loop Add respectively to to obtain the total current of line L1 and the total current of line L2 8. The small medium and low voltage closed-loop power transfer device according to claim 6 or 7, characterized in that, The modification analysis unit includes: The loop closing and power transfer rule acquisition module acquires the loop closing and power transfer rules, and the loop closing and power transfer rules include: If the line condition of the line to be looped is any one of the following: the line to be looped is connected to the same 10 kV bus of the same substation, the line to be looped is connected to the electromagnetic loop network of the same substation operating in split mode, or the electromagnetic loop network formed after the line to be looped is closed passes through a higher voltage level line and equipment, the corresponding loop closing and power transfer rules include: If the product of the total current of line L1 and the reliability coefficient and the product of the total current of line L2 and the reliability coefficient are both less than the overcurrent stage III setting value of line L1 and the overcurrent stage III setting value of line L2, there is no need for a power transfer scheme for loop closing. Otherwise, the setting value modification plan and time shall be clearly defined in the power transfer precautions. If the line condition of the line to be looped is that there is a 30° angular difference in the star-delta transformation of the line to be looped, the corresponding loop closing and power transfer rules include: If the total current of line L1 and the total current of line L2 are both greater than the overcurrent stage I setting value of each line in the line to be looped at 0 s, modify the power transfer scheme for loop closing. Otherwise, there is no need for a power transfer scheme for loop closing. The analysis and determination module compares and analyzes the total line current, and determines whether it is necessary to modify the power transfer scheme of the line to be looped according to the loop closing and power transfer rules.

9. An electronic device, characterized in that, It includes a processor and a memory. A computer program is stored in the memory, and the computer program is loaded and executed by the processor to implement the steps in the method according to any one of claims 1 to 5.

10. A storage medium, characterized in that, A computer program readable by a computer is stored on the storage medium, and the computer program is set to execute the steps in the method according to any one of claims 1 to 5 when running.

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