A method for implementing main grid reconstruction and load restoration based on hydro-thermal power units

Abstract

The present invention provides a method for implementing main grid reconstruction and load recovery based on hydro-thermal power units, which relates to the technical field of power systems. The method includes obtaining key parameters of the power grid (voltage level, structure, unit self-starting capability, etc.); constructing an electromagnetic transient simulation model based on information sorting unit capacity and line length; simulating overvoltage, unit paralleling and grid reconstruction through the model; further establishing a frequency response model to simulate load recovery; finally, formulating and deploying main grid reconstruction and load recovery plans to the power grid dispatching system based on simulation results and actual dispatching data. The present invention overcomes the blindness of power grid dispatchers in the reconstruction of the main grid and load recovery of the power grid during the black start of the power grid, and solves the problem of dispatchers' difficulty in decision-making during the black start.

Description

Technical Field

[0001] The present invention relates to the technical field of electric power systems, and in particular to a method for implementing main grid reconstruction and load recovery based on hydro-thermal power generation units. Background Art

[0002] As the proportion of new energy continues to increase, the risk of safe and stable operation of the power grid continues to increase, and the black start of the power grid has once again attracted the attention of scholars and technicians at home and abroad. The power system with a high proportion of new energy presents a complex new feature of power electronics. On the one hand, the randomness, volatility and uncertainty of new energy power generation bring new challenges to the frequency and peak regulation of the power grid; on the other hand, the replacement of traditional units with new energy has continuously reduced the effective inertia of the system, bringing new challenges to the safety and stability of the power grid, especially the frequency stability of the low inertia system. The dynamic regulation ability of the power system with a high proportion of new energy has decreased, which has weakened the system's ability to withstand active power impact, frequency fluctuations and anti-disturbance, making it easier for the failure of the local system of the power grid to cause a chain failure, resulting in a large-scale power outage accident in the power grid.

[0003] The so-called black start refers to the process of restoring the entire power system to normal operation by starting the self-starting units in the system (generally hydropower units or other units with independent operation capabilities) or by using the power of the external power grid. After the partial system is restored, the entire power supply system is eventually restored to normal operation through grid reconstruction and load recovery. According to the characteristics of the system at different stages during the recovery process, the recovery process can be divided into three stages: black start stage, main network reconstruction stage, and load recovery stage.

[0004] Black start stage: generally lasts 30 to 60 minutes. In this stage, the starting power supply first provides starting power to the tripped power supply with critical time limit, so that it can restore its power generation capacity and connect to the black start power supply to form an isolated subsystem. The starting power supply of the system can be a hydro-turbine generator, a gas turbine generator, a generator remaining in the system after the accident (such as a generator with its own factory power after tripping), or the support of the isolated subsystem and adjacent systems after decoupling. The main issues involved in this stage are: the starting and operating characteristics of the unit, the self-excitation and overvoltage problems caused by charging the unloaded line and transformer, the parallel resonance problem caused by transformer saturation, the starting of large motors, the frequency and voltage regulation problems of isolated small systems, etc. This stage is the recovery process from electromagnetic transient process, electromechanical transient process to quasi-steady state.

[0005] Main network reconstruction phase: usually lasts 3 to 4 hours. In this phase, the grid of the main grid will be gradually restored by starting large units with basic loads and putting the main transmission lines into operation. On the one hand, the connection between power plants will be strengthened to improve the reliability of power supply to the plant. On the other hand, some subsystems will be paralleled to establish a stable grid, laying the foundation for the full restoration of loads in the next phase. Of course, for some regional systems with longer interconnection lines, the operation can be postponed and put in place after the load is restored to avoid stability problems and reduce the tension of dispatchers. In addition, some lines that supply power to unimportant loads in remote areas may not be put into operation temporarily. The main issue involved in this phase is to avoid the reactive power absorbed by the generator exceeding its phase leading capacity and the voltage rise caused by the large amount of charging reactive power of the unloaded line. Sometimes, in order to absorb the reactive power generated by the line capacitor and reduce the no-load overvoltage of the line, a certain amount of load is often required.

[0006] Load recovery stage: When the thermal power unit has been started and has a certain power generation capacity, and a relatively stable grid has been established, the load can be gradually restored because the active and reactive power that the system can supply has greatly increased. The main problem at this stage is how to keep the system frequency and voltage within the allowable range and prevent the line from being overloaded. Since the load increase rate of the thermal power unit has certain limitations, the biggest factor limiting load recovery is that the system frequency should not drop too much (for example, the automatic load reduction device should not operate when the system steady-state frequency is not lower than 49.5Hz), and it should not cause low-frequency load reduction.

[0007] After the power system is completely out of power, restoring power supply is a very complicated and time-consuming task. From operating experience, it can be known that if there is a sufficient and reasonable accident recovery plan, it may help dispatchers and production operators take appropriate measures, thereby greatly reducing the power outage time; otherwise, it may prolong the power outage time and even cause serious consequences such as equipment damage. For example, in the recovery process of the 735kV system of the Canadian power grid after the accident in 1982, the terminal overvoltage multiple was too high due to the empty charging of long lines, which exceeded the insulation level of the equipment, causing damage to the transformer and lightning arrester. In Italy, after the power grid was out of power, according to the system recovery plan, the system was divided into several subsystems for restoration. After meeting certain conditions, each subsystem was connected to the grid, and the system was fully restored within 30 minutes. The two examples tell us that a well-prepared black start after the accident can restore the system to power supply in a very short time, reduce the power outage time, and have significant economic benefits. At present, most of the black start test research of the power grid focuses on the paralleling of the black start power supply and the started unit, that is, the black start stage, but does not mention the main network reconstruction stage and the load recovery stage. Therefore, strengthening the research on prevention and recovery measures for major power outages and formulating reasonable and feasible recovery plans will enable us to carry out recovery operations in a targeted manner when an accident occurs and minimize the losses caused by power outages. Summary of the invention

[0008] To this end, an embodiment of the present invention provides a main grid reconstruction and load recovery implementation method and system based on hydro-thermal power units, which is used to solve the problem that the existing technology of power grid black start research focuses on the black start stage, pays insufficient attention to the subsequent main network reconstruction and load recovery stages, and lacks comprehensive and reasonable recovery plans and measures.

[0009] In order to solve the above problems, an embodiment of the present invention provides a main grid reconstruction and load recovery implementation method based on a hydro-thermal power unit, the method comprising:

[0010] Step S1: Obtain key information of the main grid system, including voltage level U n , system structure, self-starting capability and quantity of generator sets, parameters of generator sets and related equipment, among which the generator sets with self-starting capability in the main grid system are denoted as set M, and the total number is M F ; Generator sets in the main grid system that do not have self-starting capability but whose high-voltage starting transformers are connected to the main grid voltage level on the high-voltage side are denoted as set Y, and the total number is Y F ;

[0011] Step S2: Based on the key information, the generator capacities are sorted, the line lengths between the generators are calculated and sorted, and the units to be started are determined, and an electromagnetic transient simulation model is established;

[0012] Step S3: Based on the established electromagnetic transient simulation model, overvoltage, unit paralleling and grid reconstruction simulation are carried out;

[0013] Step S4: establishing a frequency response model based on the simulation results of overvoltage, unit paralleling and grid reconstruction, and conducting load recovery simulation during the main grid reconstruction based on the established frequency response model to obtain the main grid reconstruction and load recovery implementation plan during the black start process;

[0014] Step S5: Based on the actual operation data of the power grid dispatching and the simulation results, the main grid reconstruction and load recovery scheme during the black start process is deployed to the power grid dispatching system.

[0015] Preferably, the system structure includes a water / thermal generator set in the main grid system, a generator step-up transformer, a high-voltage starting transformer of the power plant where the generator set is located, a substation bus, a circuit breaker, a transmission line, a power plant / substation bus arrester, and a bus / line shunt reactor.

[0016] Preferably, the parameters of the generator set and its related equipment specifically include:

[0017] Parameters of the generator sets in set M and set Y, parameters of the generator step-up transformers, parameters of the high-voltage starting transformers of the power plants where the generator sets are located, parameters of the transmission lines, and parameters of the bus / line shunt reactors;

[0018] The parameters of the generator include rated power, rated voltage, power factor, speed, quadrature axis transient reactance, direct axis transient reactance, quadrature axis super transient reactance, direct axis transient super transient reactance, negative sequence reactance and zero sequence reactance;

[0019] The parameters of the generator step-up transformer include rated capacity, winding connection form, high-voltage and low-voltage winding voltage ratio, impedance voltage, and tap transformation ratio;

[0020] The parameters of the high-voltage starting transformer of the power plant where the generator set is located include rated capacity, winding connection form, high-voltage and low-voltage winding voltage ratio, impedance voltage, and tap transformation ratio;

[0021] The parameters of the transmission line include line length, positive and negative zero-sequence impedance parameters, and transmission line tower type parameters;

[0022] The parameters of bus / line shunt reactors include capacity, voltage, and impedance voltage;

[0023] The parameters of busbar lightning arresters in power plants / substations include rated voltage and volt-ampere characteristics.

[0024] Preferably, the generator capacities are sorted, the line lengths between the generators are calculated and sorted, and the units to be started are determined, and an electromagnetic transient simulation model is established, which specifically includes:

[0025] Step S21: Sort the generators in the set M by capacity from small to large and record them as SF i , where i=1, 2,..., M F ;

[0026] Step S22: Initialize i=1;

[0027] Step S23: Obtaining the generator SF i , determine the generator SF i The corresponding starting unit A in the set M;

[0028] Step S24: Calculate the starting unit A and each generator unit Y in the set Y p The sum of the lengths of all the lines between the two is arranged from small to large and recorded as l Ap , where p=1, 2, ..., Y F ;

[0029] Step S25: Initialize p=1;

[0030] Step S26: Obtain path 1 Ap , determine the path l Ap The corresponding generator set X is used as the started unit;

[0031] Step S27: Based on the selected starting unit A and started unit X, an electromagnetic transient simulation model is established.

[0032] Preferably, based on the established electromagnetic transient simulation model, overvoltage, unit paralleling and grid reconstruction simulation are carried out, specifically including:

[0033] Step S31: Based on the electromagnetic transient simulation model, an overvoltage simulation is performed, including a single-machine no-load long-line overvoltage simulation, to obtain the maximum peak value of the X-terminal bus phase voltage ; Carry out non-fault phase overvoltage simulation when single-phase grounding occurs at the end of an unloaded long line, and obtain the maximum peak voltage of the non-fault phase of the X-end bus ; Carry out load shedding overvoltage simulation at the end of a single long line to obtain the maximum peak value of the bus phase voltage at the X end ; Carry out overvoltage simulation of no-load long-line operation when closing the switch to obtain the maximum peak value of the bus phase voltage at the X end ; Carry out overvoltage simulation of cutting off unloaded long line operation to obtain the maximum peak value of bus phase voltage at X end ;

[0034] Step S32: Determine the path overvoltage discrimination coefficient according to the overvoltage simulation result Is it 0? If yes, the path is invalid. If no, the generator set is recorded as N. p, the path is recorded as L Ap ;

[0035] Step S33: When p <Y F When p≥Y F When N p Construct a new set N j , and correspondingly L Ap Construct a new set L Aj , where j=1,2,…,NF; NF is satisfied The total number of generators;

[0036] Step S34: Initialize j=1;

[0037] Step S35: In the new set L Aj In the Aj The corresponding generator set is set as B, and a model is established in which the starting unit A is connected to the plant load of the generator set B and the generator set B is connected in parallel, and the starting unit A is connected to the plant load of the generator set B and the generator set B is connected in parallel.

[0038] Preferably, the path overvoltage discrimination coefficient It is expressed as:

[0039] ;

[0040] Among them, when hour, ;

[0041] when hour, ;

[0042] when hour, ;

[0043] when hour, ;

[0044] In the formula, is the power frequency overvoltage limit; is the operational overvoltage limit; System voltage level The amplitude of the maximum operating phase voltage; is the power frequency overvoltage discrimination coefficient; is the switching overvoltage discrimination coefficient.

[0045] Preferably, a frequency response model is established based on overvoltage, unit paralleling, and grid framework reconstruction simulation results. Based on the established frequency response model, load restoration simulation is carried out during the main grid framework reconstruction process to obtain the implementation plan for main grid framework reconstruction and load restoration during the black start process, specifically including:

[0046] Step S41: Establish a frequency response model for the A-B unit system, obtain the load value that satisfies the frequency deviation, and obtain the load carried by the A-B unit system determined by the frequency response simulation; and make the A-B unit system carry the load determined by the frequency response simulation.

[0047] Step S42: When j≥NF, let i = i + 1, and return to Step S23; when j < NF, then execute Step S43;

[0048] Step S43: Let j = j + 1, obtain the path L corresponding to j Aj , determine the path L Aj The corresponding generating unit is C, and establish a model for the A-B unit system to carry the auxiliary load of generating unit C and for generating unit C to be paralleled; and make the A-B unit system carry the auxiliary load of generating unit C and for generating unit C to be paralleled;

[0049] Step S44: Establish a frequency response model for the A-B-C unit system, obtain the load value that satisfies the frequency deviation, and obtain the load carried by the A-B-C unit system determined by the frequency response simulation; and make the A-B-C unit system carry the load determined by the frequency response simulation;

[0050] Step S45: When j < NF, name the A-B-C unit system as the A-B unit system, and return to Step S43;

[0051] Step S46: When j≥NF, i < M F Let i = i + 1, and return to Step S23; when j≥NF, i≥M F Obtain the implementation plan for main grid framework reconstruction and load restoration during the black start process.

[0052] Preferably, based on the actual operation data and simulation results of the power grid dispatching, deploy the main grid framework reconstruction and load restoration plan during the black start process to the power grid dispatching system, specifically including:

[0053] Step S51: In the power grid dispatching system, obtain the real-time frequency f of the high-voltage side bus of the step-up transformers of all generating units, the real-time power generation of all generating units, and the real-time power flow values of all path transmission lines in the implementation plan for main grid framework reconstruction and load restoration at time t;

[0054] Step S52: When the real-time frequency f of the high-voltage side buses of all generating unit step-up transformers is less than f set, the real-time output power of all generators is 0; when the real-time power flow of all transmission lines is 0, it is determined that a large-scale power outage occurs in the power grid at time t; otherwise, it returns to step S51; where f set To set the frequency;

[0055] Step S53: Obtain the power generation of all generator sets at time t-Δt. If the power generation of the generator set at time t-Δt is not 0, it indicates that the power grid was in operation before the large-scale power outage, and the generator set will be displayed in the dispatching system; otherwise, it indicates that the power grid was in non-operating state before the large-scale power outage, and the dispatching system does not display the generator set; Δt is the data sampling interval of the dispatching system;

[0056] Step S54: Obtain the power flow value of all path transmission lines at the time t-Δt. If the power flow value of the transmission line at the time t-Δt is not 0, it indicates that the transmission line was in operation before the large-scale power outage in the power grid, and the transmission line will be displayed in the dispatching system; otherwise, it indicates that the transmission line was in a non-operating state before the large-scale power outage in the power grid, and the dispatching system does not display the transmission line.

[0057] An embodiment of the present invention also provides an electronic device, which includes a processor, a memory and a bus system, wherein the processor and the memory are connected via the bus system, the memory is used to store instructions, and the processor is used to execute the instructions stored in the memory to implement the above-mentioned main grid reconstruction and load recovery implementation method based on hydro-thermal power units.

[0058] An embodiment of the present invention also provides a computer storage medium, which stores a computer software product. The computer software product includes several instructions for enabling a computer device to execute the above-mentioned main grid reconstruction and load recovery implementation method based on hydro-thermal power units.

[0059] It can be seen from the above technical solutions that the present invention has the following beneficial effects:

[0060] (1) The present invention proposes a systematic main grid reconstruction and load recovery implementation plan, which not only focuses on the selection of black start power sources and the parallel process of the started units, but also deeply explores the main grid reconstruction, load recovery and deployment methods in the power grid dispatching system, providing comprehensive technical support for power grid restoration.

[0061] (2) By constructing electromagnetic transient simulation models of generators and transmission lines based on actual data, as well as a frequency response model of the generator, the present invention achieves accurate simulation of key links such as overvoltage, unit paralleling, grid reconstruction and load recovery, effectively combining the advantages of numerical simulation and grid operation data, and improving the scientificity and accuracy of decision-making during the black start process.

[0062] (3) The present invention provides an effective auxiliary decision-making system for power grid dispatchers. By integrating simulation results and actual operation data, the system overcomes the blindness and difficulty of dispatchers’ decision-making during the black start process, significantly improves the efficiency and safety of power grid restoration, and ensures the rapid reconstruction of the main grid and the orderly restoration of loads. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] In order to more clearly illustrate the implementation cases of the present invention or the technical solutions in the prior art, the following is a brief description of the drawings required for use in the embodiments. By referring to the drawings, the features and advantages of the present invention will be more clearly understood. The drawings are schematic and should not be understood as limiting the present invention in any way. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. Among them:

[0064] Figure 1 A flow chart of a method for implementing main grid reconstruction and load recovery based on a hydro-thermal power unit provided in an embodiment;

[0065] Figure 2 It is a structural schematic diagram of the main grid system of the power grid in the embodiment;

[0066] Figure 3 A schematic diagram of an electromagnetic transient simulation model in an embodiment;

[0067] Figure 4 It is a schematic diagram of the starter unit A connected to the plant load of the generator unit B and the parallel model of the generator unit B in the embodiment;

[0068] Figure 5 It is a schematic diagram of the frequency response model of the AB unit system in the embodiment;

[0069] Figure 6 It is a schematic diagram of the AB unit system being loaded in the embodiment;

[0070] Figure 7 It is a schematic diagram of the AB unit system connected to the plant load of the generator set C and the parallel model of the generator set C in the embodiment;

[0071] Figure 8 A schematic diagram of establishing a frequency response model of an ABC unit system in an embodiment;

[0072] Fig. 9 It is a schematic diagram of the ABC unit system being loaded in the embodiment;

[0073] Fig.10 It is a diagram of the electromagnetic transient simulation system in the embodiment;

[0074] Fig.11This is a frequency response diagram of the A and B unit systems receiving a 14.23MW active load in the embodiment;

[0075] Fig.12 This is a frequency response diagram of the A, B, and C unit systems receiving a 30.65MW active load in the embodiment;

[0076] Fig.13 This is a frequency response diagram of the A, B, C, and D unit systems receiving a 49MW active load in the embodiment;

[0077] Fig.14 This is a frequency response diagram of the A, B, C, D, and E unit systems receiving 71MW active load in the embodiment;

[0078] Fig.15 It is a frequency response diagram of the A, B, C, D, E, and F unit systems connected to a 98.65MW active load in the embodiment;

[0079] Fig.16 It is a frequency response diagram of the A, B, C, D, E, F, G unit systems connected to a 130.66MW active load in the embodiment;

[0080] Fig.17 Schematic diagram of bus voltages of power plants A, B, C, D, E, F, and G in the embodiment;

[0081] Fig.18 A schematic diagram of system frequency in an embodiment;

[0082] Fig.19 Schematic diagram of active power of generator sets A, B, C, D, E, F, and G in the embodiment;

[0083] Fig. 20 Schematic diagram of reactive power of generator sets A, B, C, D, E, F, and G in the embodiment;

[0084] Fig.21 Schematic diagram of a restoration scheme for the main grid of the power grid in the embodiment. DETAILED DESCRIPTION

[0085] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Embodiment 1

[0086] In order to solve the problem that the existing technology of power grid black start research focuses on the black start stage, pays insufficient attention to the subsequent main network reconstruction and load recovery stage, and lacks comprehensive and reasonable recovery plans and measures. Figure 1 As shown, the embodiment of the present invention proposes a main grid reconstruction and load recovery implementation method based on a hydro-thermal power unit, the method comprising:

[0087] Step S1: Obtain key information of the main grid system, including voltage level U n , system structure, self-starting capability and quantity of generator sets, parameters of generator sets and related equipment, among which the generator sets with self-starting capability in the main grid system are denoted as set M, and the total number is M F ; Generator sets in the main grid system that do not have self-starting capability but whose high-voltage starting transformers are connected to the main grid voltage level on the high-voltage side are denoted as set Y, and the total number is Y F ;

[0088] Step S2: Based on the key information, the generator capacities are sorted, the line lengths between the generators are calculated and sorted, and the units to be started are determined, and an electromagnetic transient simulation model is established;

[0089] Step S3: Based on the established electromagnetic transient simulation model, overvoltage, unit paralleling and grid reconstruction simulation are carried out;

[0090] Step S4: establishing a frequency response model based on the simulation results of overvoltage, unit paralleling and grid reconstruction, and conducting load recovery simulation during the main grid reconstruction based on the established frequency response model to obtain the main grid reconstruction and load recovery implementation plan during the black start process;

[0091] Step S5: Based on the actual operation data of the power grid dispatching and the simulation results, the main grid reconstruction and load recovery scheme during the black start process is deployed to the power grid dispatching system.

[0092] It can be seen from the above technical solutions that the present invention provides a method for implementing main grid reconstruction and load recovery based on hydro-thermal power units. By obtaining the key information of the main grid system of the power grid in detail and establishing an accurate electromagnetic transient simulation model based on this information, the accuracy of overvoltage, unit paralleling and grid reconstruction simulation is ensured. In addition, by constructing a frequency response model, the load recovery situation during the main grid reconstruction process is further simulated, providing a detailed load recovery implementation plan for the dispatcher. Finally, the simulation results are combined with the actual power grid dispatching data to achieve the effective deployment of the main grid reconstruction and load recovery plan in the power grid dispatching system during the black start process, which greatly improves the decision-making efficiency and accuracy of the dispatcher during the black start process, reduces blindness and decision-making difficulties, and provides strong support for the rapid recovery and safe and stable operation of the power grid.

[0093] In step S1, key information of the main grid system of the power grid is obtained, including:

[0094] Voltage level of main grid system U n ;

[0095] The main grid system structure of the power grid: the water / thermal generator sets in the main grid system, the generator step-up transformer, the high-voltage starting transformer of the power plant where the generator sets are located, the substation bus, the circuit breaker, the transmission line, the power plant (substation) bus arrester and the bus / line shunt reactor, such as Figure 2 As shown;

[0096] The self-starting capability and number of generator sets: The generator sets with self-starting capability in the main grid system (including hydropower units (including pumped storage power stations) and thermal power units that can operate independently) are denoted as set M, and the total number is M F ; Generator sets in the main grid system that do not have self-starting capability but whose high-voltage starting transformers are connected to the main grid voltage level on the high-voltage side are denoted as set Y, and the total number is Y F ; A power plant with multiple generating units shall be considered as one generating unit.

[0097] Parameters of the generator sets and their related equipment: parameters of the generator sets in set M and set Y, parameters of the generator step-up transformer, parameters of the high-voltage starting transformer of the power plant where the generator sets are located, parameters of the transmission lines, parameters of the busbar lightning arresters of the power plant (substation), and parameters of the busbar / line shunt reactors. The parameters of the generator include rated power, rated voltage, power factor, speed, cross-axis transient reactance, direct-axis transient reactance, cross-axis supertransient reactance, direct-axis transient supertransient reactance, negative-sequence reactance and zero-sequence reactance, as well as the parameters of the generator excitation system and the prime mover speed control system; the parameters of the generator step-up transformer include rated capacity, winding connection form, high-low voltage winding voltage ratio, impedance voltage, and tap transformation ratio; the parameters of the high-voltage starting transformer of the power plant where the generator set is located include rated capacity, winding connection form, high-low voltage winding voltage ratio, impedance voltage, and tap transformation ratio; the parameters of the transmission line include line length, positive and negative zero-sequence impedance parameters and transmission line tower type parameters; the parameters of the bus arrester of the power plant (substation) include rated voltage and volt-ampere characteristics; the parameters of the bus / line shunt reactor include capacity, voltage, and impedance voltage.

[0098] In step S2, based on the above key information, the generator capacities are sorted, the line lengths between generators are calculated and sorted to determine the units to be started, and an electromagnetic transient simulation model is established, which specifically includes:

[0099] Step S21: Sort the generators in the set M by capacity from small to large and record them as SF i, where i=1, 2,..., M F ;

[0100] Step S22: Initialize i=1;

[0101] Step S23: Obtaining the generator SF i , determine the generator SF i The corresponding starting unit A in the set M;

[0102] Step S24: Calculate the starting unit A and each generator unit Y in the set Y p The sum of the lengths of all the lines between the two is arranged from small to large and recorded as l Ap , where p=1, 2, ..., Y F ;in , zp is the starting unit A to Y p The total number of transmission line sections; l 1 , l 2 … l zp is the length of each line section, in km;

[0103] Step S25: Initialize p=1;

[0104] Step S26: Obtain path 1 Ap , determine the path l Ap The corresponding generator set X is used as the started unit;

[0105] Step S27: Based on the selected starting unit A and the started unit X, an electromagnetic transient simulation model is established. The model includes the starting unit A, the A-side step-up transformer high-voltage side circuit breaker BRK AF , A-end transmission line circuit breaker BRK A_line , the transmission line between the started units X and AX, all substation busbars and shunt reactors on the path, the high-voltage starting transformer at the X end, and the high-voltage side circuit breaker BRK of the high-voltage starting transformer at the X end X_tranH And the low voltage side load P of the high voltage starting transformer at the X end loadX The electromagnetic transient simulation model, where P loadX Consider 8% of the rated power of the generator set at the X end, such as Figure 3 shown.

[0106] In this embodiment, in step S3, based on the established electromagnetic transient simulation model, overvoltage, unit paralleling and grid reconstruction simulation are carried out, specifically including:

[0107] Step S31: performing overvoltage simulation based on the established electromagnetic transient simulation model.

[0108] Further, step S31 specifically includes: setting the generator terminal voltage at terminal A to (0.95~1.0)U fn When the A-side step-up transformer high-voltage side circuit breaker BRK AF , X-end BRK X_line In the closed position, disconnect the high-voltage side circuit breaker BRK of the high-voltage starting transformer at the X end X_tranH ; Close the A terminal BRK A_line Based on the established electromagnetic transient simulation model, a single-machine no-load long-line overvoltage simulation is performed to observe the maximum peak value of the X-terminal bus phase voltage , where U fn is the rated voltage of the generator terminal;

[0109] Set the generator terminal voltage at end A to (0.95~1.0)U fn When the A-side step-up transformer high-voltage side circuit breaker BRK AF , A-side BRK A_line and X-side BRK X_line In the closed position, disconnect the high-voltage side circuit breaker BRK of the high-voltage starting transformer at the X end X_tranH ; Simulate a single-phase grounding fault at the X busbar, and based on the established electromagnetic transient simulation model, simulate the overvoltage of the non-fault phase when the single-phase is grounded at the end of the unloaded long line, and observe the maximum peak value of the non-fault phase voltage of the X-end busbar ;

[0110] Set the generator terminal voltage at end A to (0.95~1.0)U fn When the A-side step-up transformer high-voltage side circuit breaker BRK AF , A-side BRK A_line and X-side BRK X_line In the closed position; X-end high voltage starting transformer high voltage side circuit breaker BRK X_tranH Trip the circuit breaker from the closed state; Based on the established electromagnetic transient simulation model, perform load shedding overvoltage simulation at the end of a single long line and observe the maximum peak value of the bus phase voltage at the X end ;

[0111] Set the generator terminal voltage at end A to (0.95~1.0)U fn When the A-side step-up transformer high-voltage side circuit breaker BRK AF In the closed state, disconnect the high-voltage side circuit breaker BRK of the high-voltage starting transformer at the X end X_tranH ; A-end circuit breaker BRK A_line The three phases are closed at different times from the disconnected state. Based on the established electromagnetic transient simulation model, the overvoltage simulation of closing no-load long-line operation is carried out to observe the maximum peak value of the bus phase voltage at the X end. ;

[0112] Set the generator terminal voltage at end A to (0.95~1.0)U fn When the X-terminal high-voltage starting transformer high-voltage side circuit breaker BRK is disconnected X_tranH ; A-side step-up transformer high-voltage side circuit breaker BRK AF In the closed state; A end circuit breaker BRK A_line The circuit breaker is suddenly disconnected in the closed state; based on the established electromagnetic transient simulation model, the overvoltage simulation of the unloaded long line operation is carried out to observe the maximum peak value of the X-terminal bus phase voltage .

[0113] As an optional specific implementation, the path overvoltage discrimination coefficient It is expressed as:

[0114] ;

[0115] Among them, when hour, ;

[0116] when hour, ;

[0117] when hour, ;

[0118] when hour, ;

[0119] In the formula, The power frequency overvoltage limit is not more than 1.3 pu (pu is the abbreviation of per unit, meaning "per unit value"); Different voltage levels have different requirements for operating overvoltage limits, and 330kV, 500kV and 750kV systems should not be greater than 2.2pu, 2.0pu and 1.8pu respectively; System voltage level The amplitude of the maximum operating phase voltage; is the power frequency overvoltage discrimination coefficient; is the switching overvoltage discrimination coefficient.

[0120] Step S32: According to the overvoltage simulation result, determine whether the path overvoltage discrimination coefficient is 0. If yes, the path is invalid. If not, the generator set is recorded as N. p , the path is recorded as L Ap , where p=1, 2, ..., Y F .

[0121] Step S33: When p <Y FWhen p≥Y F When N p Construct a new set N j , and correspondingly L Ap Construct a new set L Aj , where j=1,2,…,NF; NF is satisfied The total number of generators.

[0122] Step S34: Initialize j=1.

[0123] Step S35: In the new set L Aj In the Aj The corresponding generator set is set as B, and a model is established in which the starting unit A is connected to the plant load of the generator set B and the generator set B is connected in parallel, and the starting unit A is connected to the plant load of the generator set B and the generator set B is connected in parallel.

[0124] Furthermore, step S35 specifically includes: in the new set L Aj Take j=1 and set L Aj The corresponding generator set is set as B, and a model is established for starting unit A to connect the plant load of generator set B and paralleling generator set B, such as Figure 4 Specifically, the generator terminal voltage at end A is controlled at (0.95~1.0)U fn , the bus voltage at the end B side is controlled at 0.95~1.05U n Between; close the circuit breaker BRK at end A AF , A-end circuit breaker BRK A_line , B-end circuit breaker BRK B_line After that, close the high voltage starter transformer high voltage side BRK at end B B_tranH and low voltage side circuit breaker ( Figure 4 Not shown), connected to the low voltage side load P of the high voltage starting transformer with B end loadB , the generator set at end B is started and quasi-synchronized using the circuit breaker BRK BF In parallel with the A-end generator set.

[0125] In step S4, a frequency response model is established based on the simulation results of overvoltage, unit paralleling and grid reconstruction. Based on the established frequency response model, a load recovery simulation is carried out during the main grid reconstruction process to obtain the main grid reconstruction and load recovery implementation plan during the black start process, which specifically includes:

[0126] Step S41: Establish a frequency response model of the A-B unit system (the A-B unit system is a system composed of the A unit and the B unit, and the generator unit, the starting unit, and the unit to be started can all be simply referred to as units), obtain the load value that meets the frequency deviation, get the load determined by the A-B unit system connecting the frequency response simulation, and make the A-B unit system connect the load determined by the A-B unit system connecting the frequency response simulation;

[0127] Step S42: When j ≥ NF, let i = i + 1, and return to Step S23; when j < NF, then execute Step S43;

[0128] Step S43: Let j = j + 1, obtain the path L corresponding to j Aj , and determine the path L Aj The corresponding generator unit of which is C, establish a model of the A-B unit system connecting the auxiliary load of generator unit C and the parallel operation of generator unit C, and make the A-B unit system connect the auxiliary load of generator unit C and the parallel operation of generator unit C.

[0129] Step S44: Establish a frequency response model of the A-B-C unit system, obtain the load value that meets the frequency deviation, get the load determined by the A-B-C unit system connecting the frequency response simulation, and make the A-B-C unit system connect the load determined by the A-B-C unit system connecting the frequency response simulation;

[0130] Step S45: When j < NF, name the A-B-C unit system as the A-B unit system, and return to Step S43;

[0131] Step S46: When j ≥ NF and i < M F Let i = i + 1, and return to Step S23; when j ≥ NF and i ≥ M F , obtain the implementation plan for the main grid reconstruction and load restoration during the black start process.

[0132] Further, in Step S41, establish a frequency response model of the A-B unit system, as Figure 5 shown. When both the A unit and the B unit are steam turbine generator units, use Figure 5 in (a); when both the A unit and the B unit are hydro turbine generator units, use Figure 5 in (b); when the A unit is a hydro turbine generator unit and the B unit is a steam turbine generator unit, use Figure 5 in (c). In Figure 5 : ΔP d is the per-unit value of the unbalanced active power of the system; Δf is the system frequency deviation; is the water flow time constant; K d 、K p 、K iare PID coefficients respectively; f is the system frequency. The value ranges of other parameters are shown in Table 1 below.

[0133] Table 1 Parameter value range

[0134]

[0135] Further, K m1 , K m2 is the power factor of the unit, which can be calculated according to the following formula:

[0136] ;

[0137] Load Factor K fh It can be calculated according to the following formula:

[0138] ;

[0139] In the formula, is the load power; is the system baseline capacity; is the rated power of the unit.

[0140] By changing Figure 5 middle ΔP d ,available Δf ;when At this time ΔP d This is the maximum load that can be connected to each time after the A and B units are connected in parallel. (Per unit value). and The multiplication is the nominal value of power; is the frequency deviation limit; the frequency deviation is ±0.2Hz under normal operation of the power system. When the system capacity is small, the deviation limit can be relaxed to ±0.5Hz; in this implementation, .

[0141] Furthermore, after the A and B units are connected in parallel, any substation bus in the AB unit system is connected to the system load S load1 The schematic diagram of the AB unit system connected to the load is as follows: Figure 6 shown.

[0142] Further, in step S43, the path L corresponding to j is obtained. Aj , determine the path L AjThe corresponding generator set is C, and the AB unit system is connected to the generator set C plant load and the generator set C parallel model is established, such as Figure 7 Specifically, the AB unit system to the C end of the transmission line start-end circuit breaker BRK AC_line (The busbar passing through the AB unit system path) is closed, and the C-end circuit breaker BRK of the AB unit system to the C-end transmission line, the substation busbar and shunt reactor passed through the path, and the AB unit system to the C-end transmission line C_line Charge the busbar of the power plant at end C; close the high voltage starter transformer high voltage side BRK at end C C_tranH and low voltage side circuit breaker ( Figure 7 Not shown), connect the low voltage side load P of the high voltage starting transformer with C end loadC , the C-end unit is started and quasi-synchronized using BRK CF Parallel with AB unit system; P loadC Consider it as 8% of the rated power of the generator set at end C.

[0143] Further, in step S44, a frequency response model of the ABC unit system (the ABC unit system is composed of the AB unit system and the C unit) is established, such as Figure 8 As shown in the figure, when unit A is a hydro-generator and units B and C are steam-generator units, the frequency response model of the system is shown in Figure 8 (a); When units A, B, and C are all steam turbine generator units, the frequency response model of the system is shown in Figure 8 (b); When units A and B are hydro-generators and unit C is a steam turbine generator, the frequency response model of the system is shown in Figure 8 Middle (c).

[0144] By changing Figure 8 middle ΔP d ,available Δf ;when of ΔP d That is, the maximum load S that can be taken after the AB unit system and the C unit are connected in parallel load2 .

[0145] Furthermore, after the AB unit system and the C unit are connected in parallel, any substation bus in the system composed of the AB unit system and the C unit is connected to the system load S load2 ; The schematic diagram of the ABC unit system connected to the load is as follows Fig. 9 shown.

[0146] In step S5, based on the actual operation data of the power grid dispatching and the simulation results, the main grid reconstruction and load recovery scheme in the black start process is deployed to the power grid dispatching system, specifically including:

[0147] Step S51: in the power grid dispatching system, the real-time frequency f of the high-voltage side busbars of all generator set step-up transformers in the main grid reconstruction and load recovery implementation plan at time t, the real-time power generation of all generator sets, and the real-time power flow values ​​of all transmission lines in all paths are obtained;

[0148] Step S52: When the real-time frequency f of the high-voltage busbars of all the generator step-up transformers is less than f set , the real-time output power of all generators is 0; when the real-time power flow of all transmission lines is 0, it is determined that a large-scale power outage occurs in the power grid at time t; otherwise, it returns to step S51; where f set To set the frequency;

[0149] Specifically, set Take min (the frequency setting value of the last round of low-frequency load shedding (generally 46-46.5Hz); in the case of abnormal power grid accidents, the instantaneous frequency is not less than 45Hz). In this embodiment, take f set =45Hz;

[0150] Step S53: Obtain the power generation of all generator sets at time t-Δt. If the power generation of the generator set at time t-Δt is not 0, it indicates that the power grid was in operation before the large-scale power outage, and the generator set will be displayed in the dispatching system; otherwise, it indicates that the power grid was in non-operating state before the large-scale power outage, and the dispatching system does not display the generator set; wherein Δt is the data sampling interval of the dispatching system;

[0151] Step S54: Obtain the power flow value of all path transmission lines at the time t-Δt. If the power flow value of the transmission line at the time t-Δt is not 0, it indicates that the transmission line was in operation before the large-scale power outage in the power grid, and the transmission line will be displayed in the dispatching system; otherwise, it indicates that the transmission line was in a non-operating state before the large-scale power outage in the power grid, and the dispatching system does not display the transmission line.

[0152] With the above technical solutions, it can be seen that after the power grid encounters a large-scale power outage, the dispatching system will start and display a detailed main grid reconstruction strategy, which accurately plans the following key recovery steps:

[0153] Unit and path recovery sequence: The restart order of the generator units and the corresponding transmission paths is clearly specified to ensure the orderliness and efficiency of the recovery process.

[0154] Voltage control strategy: Voltage regulation schemes from single machine to multiple machines in parallel are designed to maintain system voltage stability and support voltage management requirements during gradual recovery.

[0155] Load recovery control: Implement phased load recovery control on the entire system to ensure that system stability and reliability are guaranteed while power supply is gradually restored.

[0156] When the system meets certain conditions (i.e., M F >1), indicating that there are multiple connections to the same voltage level U n And the generator set has self-starting capability. In this case:

[0157] Independent system formation: Each generator set with self-starting capability can form its own system and an independent power subsystem.

[0158] Subsystem paralleling: If multiple subsystems have a common power plant bus, the automatic quasi-synchronization device of the power plant can be used to achieve parallel operation between subsystems to enhance the overall power supply capacity of the system. The dispatching system will display the status of these parallel subsystems and the closed-loop bus in real time.

[0159] Independent subsystem operation: If there is no common power plant bus between subsystems, each subsystem will maintain an independent operation status and be clearly presented in the dispatching system for monitoring and management.

[0160] In summary, this technical solution aims to restore power supply to the power grid quickly and orderly through refined restoration strategy planning and efficient subsystem management, while ensuring stability and safety during the system restoration process.

[0161] In order to further illustrate the technical solutions and advantages of the present invention, specific examples are provided below for illustration.

[0162] 1. Generator set parameters (as shown in Table 2 below)

[0163] Table 2 Generator set parameters

[0164]

[0165] 2. Transformer parameters (as shown in Table 3 below)

[0166] Table 3 Transformer parameters

[0167]

[0168] High voltage starting transformer parameters (as shown in Table 4 below)

[0169] Table 4 High voltage starting transformer parameters

[0170]

[0171] 4. Transmission line path parameters (as shown in Table 5 below)

[0172] Table 5 Transmission line path parameters

[0173]

[0174] In Table 5: [1] The busbar of power plant B is connected with a 120MVA shunt reactor; [2] The line side of MS substation is connected with a 150MVA shunt reactor; [3] The busbar of YD substation is connected with a 150MVA shunt reactor; [4] The busbar of power plant E is connected with a 150Mvar reactor; [5] The line side of MS substation is connected with a 150Mvar reactor; [6] The busbar of power plant F is connected with a 120MVA shunt reactor; [7] The line side of MS substation is connected with a 150MVA shunt reactor; [8] The busbar of JZ substation is connected with a 150MVA shunt reactor; [9] The busbar of YS substation is connected with a 150MVA shunt reactor.

[0175] 5. Inertia time constant H and damping D

[0176] For thermal power units, H is 8s, for hydropower units, H is 2s; D is 0.

[0177] 6. Unit adjustment coefficient

[0178] For thermal power units, R is 0.05, and for hydropower units, R is (0.02-0.04), so take 0.04.

[0179] 7. Electromagnetic transient simulation of the unit

[0180] 7.1 Electromagnetic transient simulation from unit A to unit B

[0181] The electromagnetic transient simulation system diagram from unit A to unit B is shown in Figure 10 (a). The transformer tap selection is shown in Table 6 below.

[0182] Table 6 Transformer tap selection

[0183]

[0184] (1) Generator self-excitation and no-load line capacity rise voltage verification

[0185] Simulation parameter settings: 0.5s power plant A unit is started, the unit carries transmission line 1, XZ substation bus, transmission line 2, B power plant bus and shunt reactor. The simulation results are shown in Table 7 below.

[0186] Table 7 Simulation results of generator self-excitation and no-load line capacity rise voltage verification

[0187]

[0188] (2) Simulation of non-fault phase voltage for metallic ground fault of phase A at the end of transmission line 2

[0189] At 3s, a metallic ground fault of phase A occurs at the end of transmission line 2 and lasts for 0.5s. The simulation results are shown in Table 8 below.

[0190] Table 8 Simulation results of non-fault phase voltage for metallic ground fault of phase A at the end of transmission line 2

[0191]

[0192] (3) Load shedding at the end of the line

[0193] At the end of the transmission line, the low-voltage load of the high-voltage starting transformer of power plant B is 10%. The high-voltage side circuit breaker of the high-voltage starting transformer is disconnected after 3s. The simulation results are shown in Table 9 below.

[0194] Table 9 Line end load shedding simulation results

[0195]

[0196] (4) Simulation calculation of overvoltage during closing operation of unloaded line (as shown in Table 10 below)

[0197] Table 10 Simulation results of overvoltage in no-load line closing operation

[0198]

[0199] (5) Simulation calculation of overvoltage when disconnecting unloaded line (as shown in Table 11 below)

[0200] Table 11 Simulation calculation results of overvoltage of unloaded line operation

[0201]

[0202] From the above simulation results, it can be seen that the overvoltages do not exceed the standard requirements.

[0203] 7.2 Electromagnetic transient simulation of units A to C

[0204] The electromagnetic transient simulation system diagram of units A to C is shown in Figure 10 (b). The transformer tap selection is shown in Table 12.

[0205] Table 12 Transformer tap selection

[0206]

[0207] (1) Generator self-excitation and no-load line capacity rise voltage verification

[0208] Simulation parameter settings: 0.5sA power plant is started, the unit carries transmission line 1, XZ substation bus, transmission line 2, MS substation bus shunt reactor, transmission line 3, YT substation bus, transmission line 4, C power plant bus and shunt reactor. The simulation results are shown in Table 13 below.

[0209] Table 13 Simulation results of generator self-excitation and no-load line capacity rise voltage verification

[0210]

[0211] (2) Simulation of non-fault phase voltage for metallic ground fault of phase A at the end of transmission line 4

[0212] At 3s, a metallic ground fault of phase A occurs at the end of the line and lasts for 0.5s. The simulation results are shown in Table 14 below.

[0213] Table 14 Simulation results of non-fault phase voltage for metallic ground fault of phase A at the end of transmission line 4

[0214]

[0215] (3) Load shedding at the end of the line

[0216] At the end of the line, the low voltage load of the high voltage start-up transformer of Xuangang Power Plant is 8% (cos φ =0.8), and disconnect the high voltage side circuit breaker of the high voltage starting transformer at 3s. The simulation results are shown in Table 15 below.

[0217] Table 15 Line end load shedding simulation results

[0218]

[0219] (4) Simulation calculation of overvoltage during closing operation of unloaded line (as shown in Table 16 below)

[0220] Table 16 Simulation results of overvoltage in no-load line closing operation

[0221]

[0222] (5) Simulation calculation of overvoltage when disconnecting unloaded line operation (as shown in Table 17 below)

[0223] Table 17 Simulation calculation results of overvoltage of unloaded line operation

[0224]

[0225] From the above simulation results, it can be seen that the overvoltages do not exceed the standard requirements.

[0226] 7.3 Electromagnetic transient simulation of units A to D

[0227] The electromagnetic transient simulation system diagram of units A to D is shown in (c) in Figure 10. The transformer tap selection is shown in Table 18.

[0228] Table 18 Transformer tap selection

[0229]

[0230] (1) Generator self-excitation and no-load line capacity rise voltage verification

[0231] Simulation parameter settings: 0.5sA power plant start-up, unit with transmission line 1, XZ substation bus, transmission line 2 and shunt reactor, HC substation bus, transmission line 3, JW substation bus, transmission line 4, YD substation bus, transmission line 5, D power plant bus and shunt reactor. The results are shown in Table 19 below.

[0232] Table 19 Simulation results of generator self-excitation and no-load line capacity rise voltage verification

[0233]

[0234] (2) Simulation of non-fault phase voltage for metallic ground fault of phase A at the end of the line

[0235] At 3s, a metallic ground fault of phase A occurred at the end of the line and lasted for 0.5s. The results are shown in Table 20 below.

[0236] Table 20 Simulation results of non-fault phase voltage for metallic ground fault of phase A at the end of the line

[0237]

[0238] (3) Load shedding at the end of the line

[0239] At the end of the line, the low voltage load of the high voltage start-up transformer of the D power plant is 8% (cos φ =0.8), and disconnect the high voltage side circuit breaker of the high voltage starting transformer at 3s. The results are shown in Table 21 below.

[0240] Table 21 Line end load shedding simulation results

[0241]

[0242] (4) Simulation calculation of overvoltage during closing operation of unloaded line (as shown in Table 22 below)

[0243] Table 22 Simulation calculation results of overvoltage in no-load line closing operation

[0244]

[0245] (5) Simulation calculation of overvoltage when disconnecting unloaded line operation (as shown in Table 23 below)

[0246] Table 23 Simulation calculation results of overvoltage of unloaded line operation

[0247]

[0248] From the above simulation results, it can be seen that the overvoltages do not exceed the standard requirements.

[0249] 7.4 Electromagnetic transient simulation of units A to E

[0250] The electromagnetic transient simulation system diagram of units A to E is shown in (d) in Figure 10. The transformer tap selection is shown in Table 24 below.

[0251] Table 24 Transformer tap selection

[0252]

[0253] (1) Generator self-excitation and no-load line capacity rise voltage verification

[0254] Simulation parameter settings: 0.5sA power plant start-up, unit with transmission line 1, XZ substation bus, transmission line 2, MS substation bus, transmission line 3, SZ substation bus, transmission line 4, WZ substation bus and shunt reactor, transmission line 5, E power plant bus. The results are shown in Table 25 below.

[0255] Table 25 Simulation results of generator self-excitation and no-load line capacity rise voltage verification

[0256]

[0257] (2) Simulation of non-fault phase voltage for metallic ground fault of phase A at the end of the line

[0258] At 3s, a metallic ground fault of phase A occurred at the end of the line and lasted for 0.5s. The results are shown in Table 26 below.

[0259] Table 26 Simulation results of non-fault phase voltage for metallic ground fault of phase A at the end of line

[0260]

[0261] (3) Load shedding at the end of the line

[0262] At the end of the line, the low voltage load of the high voltage start-up transformer of the E power plant is 8% (cos φ =0.8), and disconnect the high voltage side circuit breaker of the high voltage starting transformer at 3s. The results are shown in Table 27 below.

[0263] Table 27 Line end load shedding simulation results

[0264]

[0265] (4) Simulation calculation of overvoltage during closing operation of unloaded line (as shown in Table 28 below)

[0266] Table 28 Simulation calculation results of overvoltage of no-load line closing operation

[0267]

[0268] (5) Simulation calculation of overvoltage when disconnecting unloaded line operation (as shown in Table 29 below)

[0269] Table 29 Simulation calculation results of overvoltage of unloaded line operation

[0270]

[0271] From the above simulation results, it can be seen that the overvoltages do not exceed the standard requirements.

[0272] 7.5 Electromagnetic transient simulation of units A to F

[0273] The electromagnetic transient simulation system diagram of units A to F is shown in (e) in Figure 10. The transformer tap selection is shown in Table 30 below.

[0274] Table 30 Transformer tap selection

[0275]

[0276] (1) Generator self-excitation and no-load line capacity rise voltage verification

[0277] Simulation parameter settings: 0.5sA power plant start-up, unit with transmission line 1, XZ substation bus, transmission line 2, MS substation bus, transmission line 3, SZ substation bus, transmission line 4, WZ substation bus and shunt reactor, transmission line 5, F power plant bus. The results are shown in Table 31 below.

[0278] Table 31 Simulation results of generator self-excitation and no-load line capacity rise voltage verification

[0279]

[0280] (2) Simulation of non-fault phase voltage for metallic ground fault of phase A at the end of the line

[0281] At 3s, a metallic ground fault of phase A occurred at the end of the line and lasted for 0.5s. The results are shown in Table 32 below.

[0282] Table 32 Simulation results of non-fault phase voltage for metallic ground fault of phase A at the end of line

[0283]

[0284] (3) Load shedding at the end of the line

[0285] At the end of the line, the low voltage load of the F power plant high voltage start-up transformer is 8% (cos φ =0.8), and disconnect the high voltage side circuit breaker of the high voltage starting transformer at 3s. The results are shown in Table 33 below.

[0286] Table 33 Line end load shedding simulation results

[0287]

[0288] (4) Simulation calculation of overvoltage during closing operation of unloaded line (as shown in Table 34 below)

[0289] Table 34 Simulation calculation results of overvoltage in no-load line closing operation

[0290]

[0291] (5) Simulation calculation of overvoltage when disconnecting unloaded line operation (as shown in Table 35 below)

[0292] Table 35 Simulation calculation results of overvoltage of unloaded line operation

[0293]

[0294] 7.6 Electromagnetic transient simulation of units A to G

[0295] The electromagnetic transient simulation system diagram of units A to G is shown in Figure 10 (f). The transformer tap selection is shown in Table 36 below:

[0296] Table 36 Transformer tap selection

[0297]

[0298] (1) Generator self-excitation and no-load line capacity rise voltage verification

[0299] Simulation parameter settings: 0.5sA power plant start-up, unit with transmission line 1, XZ substation bus, transmission line 2, HC substation bus, transmission line 3, FR substation bus, transmission line 4, JZ substation bus and shunt reactor, transmission line 5, YS substation bus and shunt reactor, transmission line 6, G power plant bus. The results are shown in Table 37 below.

[0300] Table 37 Simulation results of generator self-excitation and no-load line capacity rise voltage verification

[0301]

[0302] (2) Simulation of non-fault phase voltage for metallic ground fault of phase A at the end of the line

[0303] At 3s, a metallic ground fault of phase A occurred at the end of the line and lasted for 0.5s. The results are shown in Table 38 below.

[0304] Table 38 Simulation results of non-fault phase voltage for metallic ground fault of phase A at the end of line

[0305]

[0306] (3) Load shedding at the end of the line

[0307] At the end of the line, the low-voltage load of the G power plant high-voltage start-up transformer is 8% (cos φ =0.8), and disconnect the high voltage side circuit breaker of the high voltage starting transformer at 3s. The results are shown in Table 39 below.

[0308] Table 39 Line end load shedding simulation results

[0309]

[0310] (4) Simulation calculation of overvoltage during closing operation of unloaded line (as shown in Table 40 below)

[0311] Table 40 Simulation calculation results of overvoltage in no-load line closing operation

[0312]

[0313] (5) Simulation calculation of overvoltage when disconnecting unloaded line operation (as shown in Table 41 below)

[0314] Table 41 Simulation calculation results of overvoltage of unloaded line operation

[0315]

[0316] From the above simulation results, it can be seen that the overvoltages do not exceed the standard requirements.

[0317] 8. System load frequency control simulation

[0318] (1) If Fig.11 As shown in the figure, when the A and B units are connected in parallel and carry 14.23MW active load, the steady-state frequency of the system is 49.5Hz. The maximum active load of the A and B units system does not exceed 14.23MW each time. Among them, the B unit contains 8% of the plant load.

[0319] (2) If Fig.12As shown in the figure, when the A and B units are connected in parallel with the C unit and then connected to a 30.65MW active load, the steady-state frequency of the system is 49.5Hz. The maximum active load of the A, B, and C units does not exceed 30.65MW each time. Among them, both B and C units contain 8% plant load.

[0320] (3) If Fig.13 As shown in the figure, when the A, B, C and D units are connected in parallel and then connected to a 49MW active load, the steady-state frequency of the system is 49.5Hz. The maximum active load of the A, B, C and D units does not exceed 49MW at any one time. Among them, B, C and D units all contain 8% plant load.

[0321] (4) If Fig.14 As shown in the figure, when the system of units A, B, C, and D is connected to unit E in parallel and connected to 71MW active load, the steady-state frequency of the system is 49.5Hz. The maximum active load of the system of units A, B, C, D, and E at any one time does not exceed 71MW. Among them, units B, C, D, and E all contain 8% plant load.

[0322] (5) If Fig.15 As shown, when the A, B, C, D, E and F units are connected in parallel and carry 98.65MW active load, the steady-state frequency of the system is 49.5Hz. The maximum active load of the A, B, C, D, E and F units does not exceed 98.65MW each time. Among them, B, C, D, E and F units all contain 8% plant load.

[0323] (6) Fig.16 As shown, when the A, B, C, D, E, F and G units are connected in parallel and then connected to a 130.66MW active load, the steady-state frequency of the system is 49.5Hz. The maximum active load of the A, B, C, D, E, F and G units does not exceed 130.66MW each time. Among them, B, C, D, E, F and G units all contain 8% plant load.

[0324] 8. Electromagnetic transient simulation of the entire process of starting path voltage, unit paralleling and load frequency control

[0325] Fig.17 This is the bus voltage diagram of power plants A, B, C, D, E, F, and G; Fig.18 It is a schematic diagram of system frequency; Fig.19 This is the active power diagram of the A, B, C, D, E, F, and G generator sets; Fig. 20 This is a schematic diagram of the reactive power of generator sets A, B, C, D, E, F, and G.

[0326] Fig.21 The restoration plan of the power grid main grid is demonstrated. Embodiment 2

[0327] An embodiment of the present invention provides an electronic device, which includes a processor, a memory and a bus system. The processor and the memory are connected through the bus system. The memory is used to store instructions, and the processor is used to execute the instructions stored in the memory to implement the above-mentioned main grid reconstruction and load recovery implementation method based on hydro-thermal power units. Embodiment 3

[0328] An embodiment of the present invention provides a computer storage medium storing a computer software product. The computer software product includes several instructions for enabling a computer device to execute the above-mentioned main grid reconstruction and load recovery implementation method based on hydro-thermal power units.

[0329] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0330] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0331] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to produce a computer-implemented process, so that the instructions executed on the computer or other programmable device provide for implementing the process in the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0332] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from them are still within the protection scope of the invention.

Claims

1. A method for implementing main grid reconstruction and load recovery based on hydro-thermal power units, characterized in that: Including: Step S1: Obtain key information of the main grid system, including voltage level U n , system structure, self-starting capability and quantity of generator sets, parameters of generator sets and related equipment, among which the generator sets with self-starting capability in the main grid system are denoted as set M, and the total number is M F ; Generator sets in the main grid system that do not have self-starting capability but whose high-voltage starting transformers are connected to the main grid voltage level on the high-voltage side are denoted as set Y, and the total number is Y F ; Step S2: Based on the key information, calculate and sort the line lengths between generators by sorting the generator capacities to determine the starting units, and establish an electromagnetic transient simulation model, specifically including: Step S21: Sort the generators in the set M by capacity from small to large and record them as SF i , where i = 1, 2, ..., M F ; Step S22: Initialize i = 1; Step S23: Obtaining the generator SF i , determine the generator SF i The corresponding starting unit A in the set M; Step S24: Calculate the starting unit A and each generator unit Y in the set Y p The sum of the lengths of all the lines between the two is arranged from small to large and recorded as l Ap , where p = 1, 2, ..., Y F ; Step S25: Initialize p = 1; Step S26: Obtain path 1 Ap , determine the path l Ap The corresponding generator set X is used as the started unit; Step S27: Based on the selected starting unit A and the starting unit X to be started, establish an electromagnetic transient simulation model; Step S3: Based on the established electromagnetic transient simulation model, conduct overvoltage, unit paralleling, and network reconstruction simulations, specifically including: Step S31: Based on the electromagnetic transient simulation model, overvoltage simulation is performed, including single-machine no-load long-line overvoltage simulation, to obtain the maximum peak value of the X-terminal bus phase voltage |U Xφmax1 |; Simulate the overvoltage of the non-fault phase when the single-phase is grounded at the end of the unloaded long line, and obtain the maximum peak value of the non-fault phase voltage of the X-end bus |U Xφmax2 |; Carry out load shedding overvoltage simulation at the end of a single long line to obtain the maximum peak value of the bus phase voltage at the X end |U Xφmax3 |; Carry out overvoltage simulation of no-load long-line operation after closing the switch to obtain the maximum peak value of the bus phase voltage at the X end |U Xφmax4 |; Perform overvoltage simulation for disconnecting unloaded long lines and obtain the maximum peak value of the bus phase voltage at the X end |U Xφmax5 |; Step S32: Determine the path overvoltage discrimination coefficient K according to the overvoltage simulation result α Is it 0? If yes, the path is invalid. If no, the generator set is recorded as N. p , the path is recorded as L Ap ; Step S33: When p <Y F When p≥Y F When K is satisfied, α N ≠ 0 p Construct a new set N j , and correspondingly L Ap Construct a new set L Aj , where j = 1, 2, ..., NF; NF is the value that satisfies K α The total number of generators ≠ 0; Step S34: Initialize j = 1; Step S35: In the new set L Aj In the Aj The corresponding generator set is set as B, and a model is established in which the starting unit A is connected to the plant load of the generator set B and the generator set B is connected in parallel, and the starting unit A is connected to the plant load of the generator set B and the generator set B is connected in parallel; Step S4: Based on the overvoltage, unit paralleling, and network reconstruction simulation results, establish a frequency response model. Based on the established frequency response model, conduct load restoration simulations during the main network reconstruction process to obtain the implementation plans for the main network reconstruction and load restoration during the black start process; Step S5: Based on the actual operation data of the power grid dispatching and the simulation results, deploy the implementation plans for the main network reconstruction and load restoration during the black start process to the power grid dispatching system.

2. The main grid reconstruction and load recovery implementation method based on hydro-thermal power units according to claim 1 is characterized in that: The system structure includes hydro / thermal power generators, generator step-up transformers, high-voltage starting transformers of the power plants where the generators are located, substation buses, circuit breakers, transmission lines, lightning arresters for power plant / substation buses, and shunt reactors for buses / lines in the main network system.

3. The main grid reconstruction and load recovery implementation method based on hydro-thermal power units according to claim 1 is characterized in that: The parameters of the generator sets and their related equipment specifically include: The parameters of the generator sets in sets M and Y, the parameters of the generator step-up transformers, the parameters of the high-voltage starting transformers of the power plants where the generator sets are located, the parameters of the transmission lines, the parameters of the lightning arresters for power plant / substation buses, and the parameters of the shunt reactors for buses / lines; Among them, the parameters of the generator include rated power, rated voltage, power factor, rotational speed, quadrature axis transient reactance, direct axis transient reactance, quadrature axis subtransient reactance, direct axis subtransient reactance, negative sequence reactance, and zero sequence reactance; The parameters of the generator step-up transformer include rated capacity, winding connection form, high- and low-voltage winding voltage ratio, impedance voltage, and tap transformation ratio; The parameters of the high-voltage starting transformer of the power plant where the generator set is located include rated capacity, winding connection form, high- and low-voltage winding voltage ratio, impedance voltage, and tap transformation ratio; The parameters of the transmission line include line length, positive, negative, and zero sequence impedance parameters, and transmission line tower type parameters; The parameters of the shunt reactor for the bus / line include capacity, voltage, and impedance voltage; The parameters of the bus lightning arrester include rated voltage and volt-ampere characteristics.

4. The main grid reconstruction and load recovery implementation method based on hydro-thermal power units according to claim 1 is characterized in that: The path overvoltage discrimination coefficient K α It is expressed as: K α =k2×k3; Among them when When k2=1; when When k2=0; when When k3=1; when When k3=0; In the formula, k gpgdy is the power frequency overvoltage limit; k czgdy is the operating overvoltage limit; U B is the system voltage level U n The amplitude of the highest operating phase voltage; k2 is the power frequency overvoltage discrimination coefficient; k3 is the operation overvoltage discrimination coefficient.

5. The main grid reconstruction and load recovery implementation method based on hydro-thermal power units according to claim 1 is characterized in that: Based on the overvoltage, unit paralleling, and network reconstruction simulation results, establish a frequency response model. Based on the established frequency response model, conduct load restoration simulations during the main network reconstruction process to obtain the implementation plans for the main network reconstruction and load restoration during the black start process, specifically including: Step S41: Establish a frequency response model for the A-B unit system, obtain the load value that satisfies the frequency deviation, obtain the load carried by the A-B unit system determined by the frequency response simulation, and make the A-B system carry the load determined by the frequency response simulation; Step S42: When j ≥ NF, let i = i + 1, and return to Step S23; when j < NF, then execute Step S43; Step S43: Let j=j+1, and obtain the path L corresponding to j Aj , determine the path L Aj The corresponding generator set is C, and a model is established for the AB generator set system to be connected with the plant load of the generator set C and the generator set C in parallel, and the AB generator set system is connected with the plant load of the generator set C and the generator set C in parallel; Step S44: Establish a frequency response model for the A-B-C unit system, obtain the load value that meets the frequency deviation, obtain the load determined by the A-B-C unit system's frequency response simulation, and make the A-B-C system carry the load determined by the frequency response simulation; Step S45: When j < NF, name the A-B-C unit system as the A-B unit system and return to Step S43; Step S46: When j≥NF, i <M F When j≥NF, i≥M F The implementation plan for main grid reconstruction and load recovery during the black start process is obtained.

6. The main grid reconstruction and load recovery implementation method based on hydro-thermal power units according to claim 5 is characterized in that: Based on the actual operation data and simulation results of the power grid dispatching, deploy the main grid reconstruction and load restoration plan during the black start process to the power grid dispatching system, specifically including: Step S51: In the power grid dispatching system, obtain the real-time frequency f of the high-voltage side bus of the step-up transformers of all generating units, the real-time power generation of all generating units, and the real-time power flow values of all path transmission lines in the implementation plan of the main grid reconstruction and load restoration at time t; Step S52: When the real-time frequency f of the high-voltage busbars of all the generator step-up transformers is less than f set , the real-time output power of all generators is 0; when the real-time power flow of all transmission lines is 0, it is determined that a large-scale power outage occurs in the power grid at time t; otherwise, it returns to step S51; where f set To set the frequency; Step S53: Obtain the power generation of all generating units at time t - Δt. If the power generation of a generating unit at time t - Δt is not 0, it indicates that the generating unit was in an operating state before the large-scale power outage of the power grid, and the generating unit will be displayed in the dispatching system; otherwise, it indicates that the generating unit was in a non-operating state before the large-scale power outage of the power grid, and the dispatching system will not display the generating unit; where Δt is the data sampling interval of the dispatching system; Step S54: Obtain the power flow value of all path transmission lines at time t - Δt. If the power flow value of a transmission line at time t - Δt is not 0, it indicates that the transmission line was in an operating state before the large-scale power outage of the power grid, and the transmission line will be displayed in the dispatching system; otherwise, it indicates that the transmission line was in a non-operating state before the large-scale power outage of the power grid, and the dispatching system will not display the transmission line.

7. An electronic device, characterized in that: The electronic device includes a processor, a memory, and a bus system. The processor and the memory are connected through this bus system. The memory is used to store instructions, and the processor is used to execute the instructions stored in the memory to implement the method for implementing the main grid reconstruction and load restoration based on thermal and hydro generating units according to any one of claims 1 to 6.

8. A computer storage medium, characterized in that The computer storage medium stores a computer software product. The computer software product includes a number of instructions for causing a computer device to execute the method for implementing the main grid reconstruction and load restoration based on thermal and hydro generating units according to any one of claims 1 to 6.

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