Short-circuit current comprehensive aid decision-making method and system with participation of new energy unit

Abstract

The invention discloses a short-circuit current comprehensive aid decision-making method participated by a new energy unit. The method comprises the following steps of obtaining a controllable new energy unit and a value range and a current value of a control parameter of the controllable new energy unit; screening out a new energy unit suitable for short-circuit current out-of-limit bus and insufficient bus control; calculating the sensitivity corresponding to different control parameters of each screened new energy unit; arranging and combining the new energy units according to the sensitivities of different control parameters of the new energy units, and finally forming a plurality of short-circuit current control schemes; all the short-circuit current control schemes are implemented respectively, parallel checking is carried out on the implemented short-circuit current and the safety and stability of the power system, and finally the optimal short-circuit current comprehensive aid decision scheme is screened out. The method has the advantages that the problem that short-circuit current in a high-proportion new energy power system exceeds the standard and is insufficient is solved, and coordination and control of short-circuit current auxiliary decision making and transient safety and stability are achieved.

Description

Technical Field

[0001] The present invention relates to a short-circuit current auxiliary method, in particular to a short-circuit current comprehensive auxiliary decision method and system involving new energy units, belonging to the technical field of power system automation. Background Art

[0002] With the construction of new power systems, the proportion of new energy installed capacity continues to increase. On the one hand, in areas with dense power grids, the continuous increase in new energy installed capacity will further promote the improvement of the short-circuit current level of the power grid, and the risk of exceeding the short-circuit current standard will increase; on the other hand, with the concentrated development of new energy in deserts, Gobi and wastelands, the short-circuit current level at the end of the power grid is insufficient, and the reliable operation of new energy faces challenges. In areas where the short-circuit current exceeds the standard, conventional dispatching and operation control measures such as line shutdown and busbar splitting to limit short-circuit current, while reducing the short-circuit current level, often weaken the grid structure, resulting in reduced power supply reliability of local power grids, uneven power flow distribution, and difficulty in arranging power outages of main transformers. It is not adaptable enough to the operation mode of the power grid, lacks flexible control measures, and is difficult to adapt to the needs of short-circuit current control decisions under the new situation. Summary of the invention

[0003] Purpose of the invention: The purpose of the present invention is to provide a short-circuit current comprehensive auxiliary decision-making method and system involving new energy units that can solve the problem of excessive and insufficient short-circuit current in a high-proportion new energy power system.

[0004] Technical solution: The short-circuit current comprehensive auxiliary decision-making method involving new energy units described in the present invention comprises the following steps:

[0005] (a) obtaining the value range and current value of the controllable new energy units and their corresponding control parameters;

[0006] (b) Calculate the influence factor of each controllable new energy unit on the faulty bus, and select the new energy units suitable for controlling the short-circuit current over-limit bus and insufficient bus;

[0007] (c) calculating the sensitivity corresponding to different control parameters of each screened new energy unit according to the value range and current value of the control parameter obtained in step (a);

[0008] (d) according to the control target amount required for the short-circuit current, each new energy unit is arranged and combined according to the sensitivity of its own different control parameters, and finally a plurality of short-circuit current control schemes are formed;

[0009] (e) implementing all short-circuit current control schemes respectively, and performing parallel verification calculations on the short-circuit currents after implementation, and preliminarily selecting control schemes that meet the short-circuit current control requirements;

[0010] (f) Implement the short-circuit current control schemes after preliminary screening respectively, and perform parallel verification calculations on the safety and stability of the implemented power system, and finally select the optimal short-circuit current comprehensive auxiliary decision-making scheme.

[0011] Preferably, the control parameters in step (a) include the overcurrent coefficient K and the reactive current multiple I qmax .

[0012] Preferably, the screening method in step (b) is to screen out the first measure set of candidate new energy units for the short-circuit current exceeding the limit bus and the second measure set of candidate new energy units for the short-circuit current insufficient bus by comparing the influencing factors with the agreed threshold values, remove the new energy units at the intersection of the first measure set and the second measure set, and finally obtain the third measure set of new energy units for the short-circuit current exceeding the limit bus and the fourth measure set of new energy units for the short-circuit current insufficient bus.

[0013] Preferably, the calculation method of the sensitivity of different control parameters of the new energy unit in step (c) includes:

[0014] (S1) determining the parameter adjustment range of each new energy unit after screening according to the current value and value range of the control parameter obtained in step (a);

[0015] (S2) Dividing the adjustment ranges of the two control parameters into five equal parts, each new energy unit can obtain five groups of adjustment plans;

[0016] (S3) respectively estimating the reactive current value provided by the five adjustment schemes of each new energy unit to the power system, calculating the impact on the fault bus, updating the voltage of the fault bus, and recalculating the short-circuit current of the fault bus with the updated voltage;

[0017] (S4) The change in short-circuit current before and after parameter adjustment is used as the sensitivity of different control parameters of each new energy unit.

[0018] Preferably, the parameter adjustment range of the third measure set for the new energy unit of the bus with over-limit short-circuit current is [minimum parameter value, current value), and the parameter adjustment range of the fourth measure set for the new energy unit of the bus with insufficient short-circuit current is (current value, maximum parameter).

[0019] Preferably, in order to ultimately control the short-circuit current of the over-limit bus and the insufficient bus within the specified value, if the multiple short-circuit current control schemes ultimately formed in the step (d) cannot meet the short-circuit current control requirements, additional conventional adjustment measures need to be added.

[0020] Preferably, in step (e), the short-circuit current after implementation is checked and calculated in parallel and then compared with the rated interrupting capacity of the circuit breaker and the minimum short-circuit current limit of the busbar.

[0021] Preferably, the safety and stability parallel verification calculation of the implemented power system in step (f) includes parallel verification of transient power angle, voltage and frequency stability of three permanent N-1 / 2 faults of key section lines.

[0022] Preferably, the transient power angle, voltage and frequency stability are three target parameters for determining the safety and stability of the power system. The lowest value of the margin of the three target parameters is taken as the safety and stability margin of the system after the corresponding short-circuit current control scheme is implemented, and the control scheme with the largest system safety and stability margin is selected as the optimal short-circuit current comprehensive auxiliary decision-making scheme.

[0023] The short-circuit current comprehensive auxiliary decision-making system involving new energy units described in the present invention includes a data acquisition module for acquiring controllable new energy units and corresponding control parameter data, a calculation module for preliminarily screening new energy units and calculating the corresponding sensitivities of different control parameters to generate short-circuit current control schemes, and a parallel verification module for performing short-circuit current parallel verification and system safety and stability parallel verification on short-circuit fault control schemes. The calculation module screens and calculates the data in the data acquisition module to obtain multiple short-circuit current control schemes, and the parallel verification module finally obtains the optimal short-circuit current comprehensive auxiliary decision-making scheme by further verifying and calculating the multiple short-circuit current control schemes.

[0024] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: 1. The present invention obtains multiple short-circuit current control schemes by proposing a screening method for new energy units and a calculation method for the sensitivity of different control parameters of new energy units, and finally obtains the optimal short-circuit current comprehensive auxiliary decision-making scheme through secondary parallel verification of short-circuit current and safety and stability, which solves the problem of excessive and insufficient short-circuit current in high-proportion new energy power systems, and realizes the coordination and control of short-circuit current auxiliary decision-making and transient safety and stability; 2. The present invention expands the short-circuit current control means, can give full play to the flexible adjustment capabilities of massive new energy power electronic equipment, realize the coordinated optimization and control of new energy and conventional short-circuit current control measures, and improves the ability of the entire power system to operate safely and stably. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the structure of the method of the present invention;

[0026] Figure 2 It is a schematic diagram of the system structure of the present invention. DETAILED DESCRIPTION

[0027] The technical solution of the present invention is further described below in conjunction with the accompanying drawings.

[0028] As shown in the figure, a short-circuit current comprehensive auxiliary decision-making method involving a new energy unit disclosed in the present invention specifically includes the following steps:

[0029] 1. Obtain candidate new energy control measures and their control parameters.

[0030] Among them, obtaining candidate new energy control measures and their control parameters includes obtaining controllable new energy units and their overcurrent coefficients K and reactive current multiples I from the candidate measures file. qmax The value range of the controllable new energy unit is obtained from the stable file mode data, and the overcurrent coefficient K and reactive current multiple I of the controllable new energy unit are obtained from the stable file mode data. qmax , and use the above data as candidate initial data.

[0031] 2. Select new energy units that meet the requirements based on the short-circuit current exceeding the limit bus and insufficient bus.

[0032] Among them, the screening methods for the new energy unit measure set include:

[0033] (2.1) Calculate the mutual impedance between the faulty busbar and the candidate renewable energy unit, and obtain the influence factor F of the candidate renewable energy unit on the faulty busbar ij , the calculation formula is:

[0034]

[0035] Among them, Z ij represents the mutual impedance of candidate renewable energy unit i to fault bus j, Z jj represents the self-impedance of the fault bus j.

[0036] (2.2) Screen out the candidate new energy units whose impact factor on the short-circuit current over-limit bus is greater than the set threshold value of 0.005, and record them as the first measure set;

[0037] (2.3) Screen out the candidate new energy units whose impact factor on the short-circuit current insufficient bus is greater than the set threshold value of 0.005, and record them as the second measure set;

[0038] (2.4) The intersection of the first measure set and the second measure set is recorded as the intersection measure set;

[0039] (2.5) In the first measure set, the new energy units in the intersecting measure set are removed to obtain the third measure set of new energy units with short-circuit current exceeding the limit bus;

[0040] (2.6) In the second measure set, the new energy units in the intersecting measure set are removed to obtain the fourth measure set of new energy units with insufficient short-circuit current in the busbar.

[0041] 3. Calculate the sensitivity of different control parameters of each new energy unit.

[0042] Among them, the calculation method of different control parameter sensitivities of new energy units includes:

[0043] (3.1) According to the overcurrent coefficient K and the reactive current multiple I qmax The current value and value range of determine the adjustment range of each new energy unit parameter;

[0044] Among them, in order to ensure that the short-circuit current is adjusted within the effective range, for the new energy units in the third measure set, the values ​​of the two parameters can only be reduced, that is, the parameter adjustment range is [minimum parameter value, current value); for the new energy units in the fourth measure set, the values ​​of the two parameters can only be increased, that is, the parameter adjustment range is (current value, maximum parameter].

[0045] (3.2) According to the overcurrent coefficient K and the reactive current multiple I qmax The adjustment range of the two parameters is divided into 5 equal parts at the same time, so as to obtain 5 groups of adjustment plans for each new energy unit;

[0046] (3.3) Estimate the reactive current value I provided by the five adjustment schemes of each new energy unit to the system q , I q The estimation formula is:

[0047]

[0048] Among them, U t Take the new energy overcurrent coefficient K and the reactive current multiple I qmax is the terminal voltage after the fault when the current calculation parameters are used, I N Refers to the rated current of the new energy unit, U t Refers to the voltage drop value at the grid connection point of the new energy unit after a fault.

[0049] (3.4) Calculation I q Impact on the faulty bus: Update the voltage of the faulty bus, and recalculate the short-circuit current of the faulty bus by dividing the updated voltage by the self-impedance of the faulty bus;

[0050] (3.5) The change in short-circuit current before and after parameter adjustment is used as the sensitivity of the control measures of each renewable energy unit.

[0051] 4. According to the control target required for the short-circuit current, each new energy unit is arranged and combined according to the sensitivity of its own different control parameters, and finally multiple short-circuit current control schemes are formed. The specific steps include:

[0052] (4.1) For the control measures set of new energy units, sort them by sensitivity to form a measures queue, and estimate whether the control measures of new energy units can meet the control requirements of a single bus short-circuit current based on the sensitivity and control target;

[0053] (4.2) If the control measures of the new energy unit meet the control requirements, a combined measure set of a single bus short-circuit current is generated according to the measure queue;

[0054] (4.3) If the control measures of the new energy units cannot control the short-circuit current of the over-limit bus to below the rated interrupting capacity of its circuit breaker, conventional adjustment measures need to be added. Conventional measures include shutting down generators, shutting down lines, shutting down transformers, and putting in series reactors. Conventional measures are sorted according to the comprehensive performance indicators of priority and sensitivity to form a measure queue, and a combined measure set of a single bus short-circuit current is generated according to the measure queue;

[0055] (4.4) If the measures taken by the new energy units cannot control the short-circuit current of the busbar with insufficient short-circuit current to above the specified value, conventional measures are taken for recovery. The recovery measures include commissioning units, commissioning lines, commissioning transformers, restoring string operation, and busbar operation. The recovery measures are sorted according to the comprehensive performance indicators of priority and sensitivity to form a measure queue, and a combined measure set for a single busbar short-circuit current is generated according to the measure queue;

[0056] (4.5) Based on the combined measures corresponding to a single bus short-circuit current, a control scheme for multiple bus short-circuit currents is formed through permutations and combinations.

[0057] 5. Implement all short-circuit current control schemes separately, and perform parallel verification calculations on the short-circuit currents after implementation, and preliminarily select control schemes that meet the short-circuit current control requirements.

[0058] The short-circuit current after the control scheme is applied is checked and calculated in parallel and compared with the rated interrupting capacity of the circuit breaker and the minimum short-circuit current limit of the busbar. The scheme in which the short-circuit current meets the requirements after the control measures are applied is used as the safety and stability verification scheme.

[0059] 6. Implement the short-circuit current control schemes after preliminary screening respectively, and perform safety and stability parallel verification calculations on the implemented power system, and finally select the optimal short-circuit current comprehensive auxiliary decision-making scheme. The specific steps include:

[0060] (6.1) Perform a parallel check of transient power angle, voltage and frequency stability for the three-permanent N-1 / 2 fault of the critical section line after the control measures are applied;

[0061] (6.2) The minimum value of the system transient power angle, voltage and frequency stability margin under all faults is taken as the safety stability margin of the system after the corresponding control measures are taken;

[0062] (6.3) Select the control measure with the largest system safety and stability margin as the optimal comprehensive auxiliary decision-making solution.

[0063] The short-circuit current comprehensive auxiliary decision-making system involving new energy units described in the present invention specifically includes: a data acquisition module, used to obtain candidate new energy control measures and their control parameters; a calculation module, used to screen the new energy unit measure set according to the short-circuit current over-limit bus and insufficient bus; and used to calculate the sensitivity corresponding to different control parameters of each new energy unit; and used to generate a control scheme set according to the short-circuit current result of the fault bus, the priority of the measure and the control target; a parallel verification module, used to issue the control scheme, perform short-circuit current parallel verification calculation, and retain the control scheme that meets the short-circuit current calculation requirements; and used to issue the control scheme, perform safety and stability parallel verification calculation, and select the optimal comprehensive auxiliary decision-making measure according to the system safety and stability indicators.

[0064] In the construction of the power system, the short-circuit current comprehensive auxiliary decision-making method and system for the participation of the new energy units described in the present invention can be operated in the following device, which includes a processor and a memory, the memory stores computer instructions, and the processor is used to execute the computer instructions stored in the memory. When the computer instructions are executed by the processor in the steps of the method of the present invention, the technical effect consistent with the above method can be achieved. Among them, the memory may include a computer system readable medium in the form of a volatile memory, such as a random access memory (RAM) and / or a cache memory, and the device may further include other removable / non-removable, volatile / non-volatile computer system storage media, and the memory can be used to read and write non-removable, non-volatile magnetic media. A program with a set (at least one) of program modules can be stored in, for example, a memory, such program modules include but are not limited to an operating system, one or more application programs, other program modules and program data, and the program modules generally perform the functions and methods described in the present invention; the processor executes various functional applications and data processing by running the program stored in the memory, and can also implement the method provided by the present invention.

Claims

1. A short-circuit current comprehensive auxiliary decision-making method involving new energy units, characterized in that: The following steps are involved: (a) obtaining the value range and current value of the controllable new energy units and their corresponding control parameters; (b) Calculate the influence factor of each controllable new energy unit on the faulty bus, and select the new energy units suitable for controlling the short-circuit current over-limit bus and insufficient bus; (c) calculating the sensitivity corresponding to different control parameters of each screened new energy unit according to the value range and current value of the control parameter obtained in step (a); (d) according to the control target amount required for the short-circuit current, each new energy unit is arranged and combined according to the sensitivity of its own different control parameters, and finally a plurality of short-circuit current control schemes are formed; (e) implementing all short-circuit current control schemes respectively, and performing parallel verification calculations on the short-circuit currents after implementation, and preliminarily selecting control schemes that meet the short-circuit current control requirements; (f) Implement the short-circuit current control schemes after preliminary screening respectively, and perform parallel verification calculations on the safety and stability of the implemented power system, and finally select the optimal short-circuit current comprehensive auxiliary decision-making scheme.

2. According to claim 1, a short-circuit current comprehensive auxiliary decision-making method involving new energy units is characterized by: The control parameters in step (a) include the overcurrent coefficient K and the reactive current multiple I qmax .

3. According to claim 1, a short-circuit current comprehensive auxiliary decision-making method involving new energy units is characterized by: The screening method in the step (b) is to screen out the first measure set of candidate new energy units for the short-circuit current exceeding the limit bus and the second measure set of candidate new energy units for the short-circuit current insufficient bus by comparing the influencing factors with the agreed threshold values, remove the new energy units at the intersection of the first measure set and the second measure set, and finally obtain the third measure set of new energy units for the short-circuit current exceeding the limit bus and the fourth measure set of new energy units for the short-circuit current insufficient bus.

4. According to claim 1, a short-circuit current comprehensive auxiliary decision-making method involving new energy units is characterized by: The calculation method of different control parameter sensitivities of the new energy unit in step (c) includes: (S1) determining the parameter adjustment range of each new energy unit after screening according to the current value and value range of the control parameter obtained in step (a); (S2) Dividing the adjustment ranges of the two control parameters into five equal parts, each new energy unit can obtain five groups of adjustment plans; (S3) Estimate the reactive current value I provided by the five adjustment schemes of each new energy unit to the power system q , calculate I q Impact on the faulty bus: Update the voltage of the faulty bus and recalculate the short-circuit current of the faulty bus using the updated voltage; (S4) The change in short-circuit current before and after parameter adjustment is used as the sensitivity of different control parameters of each new energy unit.

5. A short-circuit current comprehensive auxiliary decision-making method involving new energy units according to claim 3 or 4, characterized in that: The parameter adjustment range of the third measure set for the new energy unit of the short-circuit current exceeding the limit bus is [parameter minimum value, current value), and the parameter adjustment range of the fourth measure set for the new energy unit of the short-circuit current insufficient bus is (current value, parameter maximum value].

6. The short-circuit current comprehensive auxiliary decision-making method involving new energy units according to claim 1 is characterized in that: If the multiple short-circuit current control schemes finally formed in the step (d) cannot meet the short-circuit current control requirements, it is necessary to add conventional adjustment measures to ultimately control the short-circuit current of the over-limit bus and the insufficient bus within the specified value.

7. The short-circuit current comprehensive auxiliary decision-making method involving new energy units according to claim 1 is characterized in that: In the step (e), the short-circuit current after implementation is checked and calculated in parallel and then compared with the rated interrupting capacity of the circuit breaker and the minimum short-circuit current limit of the busbar.

8. The short-circuit current comprehensive auxiliary decision-making method involving new energy units according to claim 1 is characterized in that: The safety and stability parallel verification calculation of the implemented power system in step (f) includes parallel verification of transient power angle, voltage and frequency stability of three permanent N-1 / 2 faults of key section lines.

9. A short-circuit current comprehensive auxiliary decision-making method involving new energy units according to claim 8, characterized in that: The transient power angle, voltage and frequency stability are three target parameters for determining the safety and stability of the power system. The lowest value of the margin of the three target parameters is taken as the safety and stability margin of the system after the corresponding short-circuit current control scheme is implemented, and the control scheme with the largest system safety and stability margin is selected as the optimal short-circuit current comprehensive auxiliary decision-making scheme.

10. A short-circuit current comprehensive auxiliary decision-making system involving new energy units, characterized in that: It includes a data acquisition module for acquiring controllable new energy units and corresponding control parameter data, a calculation module for preliminarily screening new energy units and calculating the corresponding sensitivities of different control parameters to generate short-circuit current control schemes, and a parallel verification module for performing short-circuit current parallel verification and system safety and stability parallel verification on the short-circuit current control schemes. The calculation module screens and calculates the data in the data acquisition module to obtain multiple short-circuit current control schemes, and the parallel verification module further verifies and calculates the multiple short-circuit current control schemes to finally obtain the optimal short-circuit current comprehensive auxiliary decision-making scheme.

Images