CN114709860A

CN114709860A - Pre-control method and device for safe and stable operation mode of power grid

Info

Publication number: CN114709860A
Application number: CN202210437965.1A
Authority: CN
Inventors: 陈勇; 李胜男; 郭恒道; 郭琦; 朱益华; 常东旭
Original assignee: CSG Electric Power Research Institute; Electric Power Research Institute of Yunnan Power Grid Co Ltd
Current assignee: CSG Electric Power Research Institute; Electric Power Research Institute of Yunnan Power Grid Co Ltd
Priority date: 2022-04-25
Filing date: 2022-04-25
Publication date: 2022-07-05

Abstract

The application relates to a method and a device for pre-controlling a safe and stable operation mode of a power grid; the method comprises the steps of establishing a plurality of sets of simulation models of operation modes according to preset operation data; determining all risks in each set of operation mode aiming at the simulation model of the operation mode; aiming at all scanned risks, simulating and developing the pre-control of the safe and stable operation mode of the power grid to obtain a simulation pre-control result meeting the stability criterion; and determining corresponding pre-control parameters according to the simulation pre-control result aiming at each set of operation mode. According to the scheme, the safety and stability of regional power grid operation are effectively improved by formulating the safe and stable operation mode pre-control method, the influence of faults on the access of the alternating current and direct current receiving end to a heavy load area is reduced, the safe and stable operation of the power grid is ensured, and the conditions of large influences such as direct current blocking, alternating current system voltage breakdown and the like caused by faults are avoided.

Description

Pre-control method and device for safe and stable operation mode of power grid

Technical Field

The application relates to the technical field of power grid safety and stability control, in particular to a method and a device for pre-controlling a safety and stability operation mode of a power grid.

Background

The large-scale power transmission network is formed by connecting a main power grid (called a main grid for short) and a plurality of regional power grids. Regional networks are generally classified into a transmission-end power grid, an intermediate power grid and a reception-end power grid according to the position of the regional network in an electric power system. The receiving-end power grid is a regional power grid which is arranged at one end of the main grid and mainly receives power. The total power generation capacity of the receiving-end power grid is smaller than the load capacity of the receiving-end power grid, so that the receiving-end power grid needs to receive power from other power grids to ensure the balance of power generation and utilization.

The power grid safety and stability control is a control method for restoring a power system to a normal operation state by executing various emergency control measures after the power system is in an emergency state. The high-voltage direct-current transmission adopts a high-power long-distance direct-current transmission mode by utilizing the advantages that stable direct current has no inductive reactance, capacitive reactance does not work, no synchronization problem and the like; the power transmission process is direct current.

The safe and stable operation of the power system plays a vital role in the operation of a power grid, ensures the stable supply of power and plays a supporting role in the stability and development of the economic society. With the rapid development and application of the direct-current transmission technology, some areas with weak and lacking power supplies are accessed with long-distance large-capacity direct-current feed-in order to adapt to the rapid growth of industrial loads, however, before the power grid architecture is perfect or under the condition of key line maintenance, various operation risks may still exist in the heavy-load area of the alternating current/direct current receiving end, and even the heavy load shedding and direct-current blocking have great influence on the power grid operation in other areas. Therefore, aiming at the heavy load area of the alternating current/direct current receiving end, under the condition of incomplete power grid structure or key line maintenance, the safe and stable operation of the power grid can be ensured by a mode pre-control method, the requirement of safety and stability guide rule of a power system is met, and meanwhile, when a fault occurs, direct current locking is not caused so as to avoid the influence caused by enlarged fault. Dc blocking refers to the dc transmission system stopping delivering power.

In the related art, most of the existing safety and stability control strategies and mode pre-control methods are designed for solving the stability problem existing in part of areas of a large system, or are only formulated for heavy load areas of a direct current receiving end, and no safety and stability mode pre-control method for the areas which are not only the receiving end of an alternating current system but also the receiving end of a direct current system and are directly accessed to the heavy load areas exists.

Disclosure of Invention

In order to overcome the problems in the related art at least to a certain extent, the application provides a method and a device for pre-controlling the safe and stable operation mode of a power grid.

According to a first aspect of an embodiment of the present application, a method for pre-controlling a safe and stable operation mode of a power grid is provided, which includes:

establishing a plurality of sets of simulation models of operation modes according to preset operation data;

determining all risks in each set of operation mode aiming at the simulation model of the operation mode;

aiming at all scanned risks, simulating and developing the pre-control of the safe and stable operation mode of the power grid to obtain a simulation pre-control result meeting the stability criterion; the stability criterion is a condition that the pre-controlled effect meets the condition that the AC/DC system can recover stability after a fault;

and determining corresponding pre-control parameters according to the simulation pre-control result aiming at each set of operation mode.

Further, the preset operation data is typical annual operation mode data;

the operation mode comprises the following steps: a withering mode, a rich and generous mode and a rich and small mode;

the simulation model comprises each set of operation mode, and all the corresponding related line maintenance modes and main transformer maintenance modes.

Further, the determining all risks in the operating mode includes:

under the condition of load and direct current power of a given operation mode, scanning the risk of accessing an alternating current/direct current receiving end into a heavy load area;

the risks in each mode of operation are numbered separately.

Further, the risk comprises at least one of: n-1 fault, N-2 fault, N-1 fault in maintenance mode, and N-2 fault in maintenance mode.

Further, the simulation development of the pre-control of the safe and stable operation mode of the power grid comprises the following steps:

under the condition of direct current outage, carrying out simulation tests on faults corresponding to all risks;

and under the condition of recovering the direct current operation, carrying out simulation tests on the faults corresponding to the risks.

Further, the stability criterion includes at least one of: the line or the main transformer is not overloaded, the power angle is not unstable, the steady-state voltage of the system is not unstable, the steady-state frequency of the system is not unstable, the transient voltage of the system is not unstable, the direct current is not locked, and the frequency of the direct current commutation failure is not more than a preset threshold value.

Further, under the condition of direct current outage, a simulation test is performed on the fault corresponding to each risk, and the simulation test includes:

under the condition of direct current outage, carrying out a simulation test on the fault corresponding to the risk i;

by gradually reducing the load amount accessed by the alternating current and direct current receiving end until the fault corresponding to the risk i occurs, the system can be recovered to be stable, and the load amount Pi at the moment is recorded.

Further, under the condition of recovering the direct current operation, a simulation test is performed on the faults corresponding to the risks, and the simulation test comprises the following steps:

under the condition that the load quantity is Pi, the direct current operation is recovered;

and gradually reducing the direct current power until the fault corresponding to the risk i occurs, recovering the stability of the system, and recording the direct current power Pdci at the moment.

Further, the determining the corresponding pre-control parameters according to the simulation pre-control result includes:

the final load amount Pload for the mode precontrol is determined as: pload min (P1, P2 … Pi);

the final direct current power Pdc of the mode pre-control is determined as follows: pdc min (Pdc1, Pdc2 … Pdci).

According to a second aspect of the embodiments of the present application, there is provided a precontrol device for a safe and stable operation mode of a power grid, including:

the model establishing module is used for establishing a plurality of sets of simulation models of operation modes according to preset operation data;

the risk determination module is used for determining all risks in each set of operation mode aiming at the simulation model of the operation mode;

the simulation pre-control module is used for simulating and developing pre-control of a safe and stable operation mode of the power grid aiming at all the scanned risks and obtaining a simulation pre-control result meeting the stability criterion; the stability criterion is a condition that the pre-controlled effect meets the condition that the AC/DC system can recover stability after a fault;

and the parameter determining module is used for determining corresponding pre-control parameters according to the simulation pre-control result aiming at each set of operation mode.

The technical scheme provided by the embodiment of the application has the following beneficial effects:

according to the scheme, the safety and stability of regional power grid operation are effectively improved by formulating the safe and stable operation mode pre-control method, the influence of faults on the access of the alternating current/direct current receiving end to a heavy load area is reduced, the safe and stable operation of the power grid is ensured, and the conditions of large influences such as direct current blocking, alternating current system voltage collapse and the like caused by faults are avoided.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and together with the description, serve to explain the principles of the application.

Fig. 1 is a flowchart illustrating a method for pre-controlling a safe and stable operation mode of a power grid according to an exemplary embodiment.

Fig. 2 is a block diagram illustrating a configuration of a pre-control device in a safe and stable operation mode of a power grid according to an exemplary embodiment.

Detailed Description

Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. The following description refers to the accompanying drawings in which the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. Rather, they are merely examples of methods and apparatus consistent with certain aspects of the present application, as detailed in the appended claims.

To further detail the technical solution of the present application, the state of the art is first specifically explained.

Since the electrical load of the end user decreases (for example, a large-scale power utility failure or a large-area line fault outage), the power generation of the turbine generator of the power plant exceeds the amount delivered to the user, and the power plant is required to reduce the power generation to a value that is appropriate for the actual load. Or internal to the plant, the grid outlet circuit breaker suddenly trips, the load of the turbogenerator suddenly drops to substantially zero, and these actions performed by the power plant are called load shedding.

The load shedding is divided into two types, one type is active load shedding: when the active power provided by the power grid is larger than the active power required by the system, part of unimportant loads are actively thrown away, and the power supply quality of the power grid is improved. One is fault load shedding, and the accident is caused by the tripping of a main switch of a generator, the tripping of a main valve of a steam turbine and the like besides the abnormal condition of a power grid. When the power station suddenly gets rid of a large amount of loads, the steam flow of the two loops is sharply reduced, so that the temperature and the pressure of the coolant of the first loop are rapidly increased. This is a load dump event.

Before the power grid architecture is perfect or under the condition of key line maintenance, various operation risks still exist in the heavy load area of the alternating current/direct current receiving end, and even the heavy load shedding and direct current blocking have a great influence on the power grid operation of other areas.

With the rapid development of economy, the maturity of the direct current transmission technology will increase the number of scenes, that is, the direct current receiving end area has the characteristics of weak power support at the end of the alternating current system, heavy load access and the like, and in such scenes, due to the fact that the power grid construction falls behind the speed of economic development load increase and due to key line maintenance, a proper safe and stable operation mode pre-control method needs to be established for the scenes.

The existing safe and stable operation mode pre-control method does not simultaneously give consideration to characteristics of a direct current system, an alternating current system and heavy load, and can cause serious consequences of low voltage of the system, incapability of recovering voltage breakdown and direct current locking after partial faults, and even cause the accident to be expanded to the breakdown of the whole power system.

Aiming at the problems, the invention aims to provide a safe and stable operation mode pre-control method for heavy load of an alternating current/direct current receiving end. The method considers the scene that the alternating current receiving end and the direct current receiving end are connected into the heavy load, combines the direct current receiving end, the weak power support at the tail end of the alternating current system and the characteristics of the power grid in the heavy load connection area, can effectively guarantee the safe and stable operation of the regional power grid, and avoids the problems of direct current blocking, transient low voltage and voltage breakdown caused by regional faults.

Fig. 1 is a flowchart illustrating a method for pre-controlling a safe and stable operation mode of a power grid according to an exemplary embodiment. The method may comprise the steps of:

According to the scheme, the safety and stability of regional power grid operation are effectively improved by formulating the safe and stable operation mode pre-control method, the influence of faults on the access of the alternating current and direct current receiving end to a heavy load area is reduced, the safe and stable operation of the power grid is ensured, and the conditions of large influences such as direct current blocking, alternating current system voltage breakdown and the like caused by faults are avoided.

It should be understood that, although the steps in the flowchart of fig. 1 are shown in order as indicated by the arrows, the steps are not necessarily performed in order as indicated by the arrows. The steps are not performed in the exact order shown and described, and may be performed in other orders, unless explicitly stated otherwise. Moreover, at least a portion of the steps in fig. 1 may include multiple sub-steps or multiple stages that are not necessarily performed at the same time, but may be performed at different times, and the order of performance of the sub-steps or stages is not necessarily sequential, but may be performed in turn or alternately with other steps or at least a portion of the sub-steps or stages of other steps.

In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention are described in further detail below with reference to the accompanying drawings.

In some embodiments, the preset operation data is typical annual operation mode data;

Specifically, according to typical annual operation mode data, four sets of operation modes such as a withered large (KD) mode, a withered small (KX) mode, a full large (FD) mode and a full small (FX) mode are established, and simulation models of all related line maintenance modes and main transformer maintenance modes are established. And scanning risks of the AC/DC receiving end accessing a heavy load area under the condition of the load and the DC power of the data in the given mode, wherein the risks comprise N-1 faults, N-2 faults, N-1 faults in the maintenance mode and the condition that the AC/DC system is unstable after N-2 faults in the maintenance mode.

It should be noted that the "annual typical operation mode data" is general data in the industry, is calculated and provided by a scheduling mechanism every year, and is used as annual typical operation mode data for various planning and test reference; the data volume is large, the related content is large, and the description is omitted. The four sets of operation modes belong to the mode data of the annual typical operation mode data, and the annual typical operation mode number comprises the four operation mode data.

"simulation model" means modeling with electric system analysis software based on the aforementioned data. Because even if the given data is the same, there are nuances that model with different software; the scheme of the application is not specific to a certain specific software, and can be realized by adopting various analysis software commonly used in the industry, so that the application uses a simulation model as a general name. Based on the established simulation model, the general simulation analysis software of the power system mainly has the functions of simulating and scanning all related risks, such as setting an N-1 fault and an N-2 fault and then carrying out simulation calculation.

In some embodiments, the determining all risks in the operating mode includes:

the risks in each mode of operation are numbered separately.

Specifically, the risk numbers scanned in the dry and large operation mode are as follows: KD1, KD2 …; the scanned risks in the small operation mode are numbered as follows: KX1, KX2 …; the risks scanned in the rich operating mode are numbered as follows: FD1, FD2 …; the risk numbers of all scanned risks in the small and rich operating mode are as follows: FX1, FX2 ….

In some embodiments, the risk comprises at least one of: n-1 fault, N-2 fault, N-1 fault in maintenance mode, and N-2 fault in maintenance mode.

The N-1 fault means that in a normal operation mode, any one element in the power system has no fault or is disconnected due to the fault, the power system can keep stable operation and normal power supply, other elements are not overloaded, and the capability of the system for stable and continuous power supply can be kept.

The N-2 fault means that in a normal operation mode, any two elements in the power system have no fault or are disconnected due to faults, the power system can keep stable operation and normal power supply, other elements are not overloaded, and the capability of the system for stable and continuous power supply can be kept.

In some embodiments, the simulating development of the pre-control of the safe and stable operation mode of the power grid includes: under the condition of direct current outage, carrying out simulation tests on faults corresponding to all risks; and under the condition of recovering the direct current operation, carrying out simulation tests on the faults corresponding to the risks.

And aiming at all scanned risks, power grid safe and stable operation mode pre-control is carried out through power system analysis software, and the effect after pre-control is required to meet the requirement that the alternating current and direct current system can be recovered and stabilized after a fault.

In some embodiments, the stability criterion includes at least one of: the line or the main transformer is not overloaded, the power angle is not unstable, the steady-state voltage of the system is not unstable, the steady-state frequency of the system is not unstable, the transient voltage of the system is not unstable, the direct current is not locked, and the frequency of the direct current commutation failure is not more than a preset threshold value. The preset threshold may be set to a specific value according to an actual application scenario, for example, in some embodiments, the preset threshold may be set to 1 time.

The stability criteria mainly include: 1) the line or the main transformer is not overloaded after the fault; 2) the power angle is not unstable after the fault; 3) the steady state voltage of the system is not unstable after the fault, namely the steady state voltage of the system can be maintained between 0.95 pu and 1.05pu to operate after the fault; 4) the steady-state frequency of the system is not unstable after the fault, namely the steady-state frequency of the system can be maintained between 49.8 Hz and 50.2Hz after the fault; 5) the transient voltage of the system is not unstable after the fault, namely the voltage of the bus can be recovered to be more than 0.75pu within 1s after the fault; 5) direct current is not locked after a fault; 6) the failure times of the direct current commutation after the fault are not more than 1.

It should be noted that the term "no instability of power angle" is a term commonly used in the art, and a person skilled in the art can clearly understand the meaning of the term, so that the detailed description is not repeated in this application.

In some embodiments, under the condition of dc shutdown, performing a simulation test on a fault corresponding to each risk includes:

Take a run mode as an example: aiming at the data of the running mode with large scale, carrying out a simulation test on the fault corresponding to the risk i under the condition of direct current shutdown for the ith risk (i is the scanned risk corresponding number under the running mode with large scale), and gradually reducing the load amount (taking the load amount of the data with the original mode as an initial value) of the AC/DC receiving end access until the fault corresponding to the risk i occurs, so that the system can be recovered to be stable. The load amount Pi at this time is recorded. The term "resume stable" is used herein in reference to a dc outage situation. The simulation pre-discipline steps of the other three operation modes are the same as the Suda operation mode, and are not described again.

In some embodiments, in the case of recovering the dc operation, performing a simulation test on a fault corresponding to each risk includes:

under the condition that the load is Pi, the direct current operation is recovered;

and gradually reducing the direct current power until the fault corresponding to the risk i occurs, recovering the system to be stable, and recording the direct current power Pdci at the moment.

Take a big-end operation mode as an example: and under the condition that the load quantity is Pi, the direct current operation is recovered, and the system can be recovered to be stable by gradually reducing the direct current power (taking the direct current rated power as an initial value) until the fault corresponding to the risk i occurs. The dc power Pdci at this time is recorded. The "recovery from stabilization" here is that the dc operation has been recovered, unlike the aforementioned precondition. The simulation pre-discipline steps of the other three operation modes are the same as the Suda operation mode, and are not described again.

In some embodiments, the determining the corresponding pre-control parameter according to the simulation pre-control result includes:

the final load quantity Pload of the mode precontrol is determined as: pload min (P1, P2 … Pi);

Wherein, the min (#) function is a minimum function.

The determined Pload and Pdc are the operation mode pre-control scheme under the mode data.

The pre-control scheme is a scheme that enables the power system to operate safely and stably under certain specific conditions. The scheme provided by the patent is to control two variable sizes of Pload (final load amount) and Pdc (direct current operation power), so that the targeted regional power grid meets the safe and stable operation criterion of the power grid.

The steps are explained by taking a dry operation mode as an example, and the operations are repeated aiming at the other three sets of operation mode data such as a dry operation mode, a rich operation mode and the like until all risks have corresponding safe and stable operation mode pre-control schemes.

The method mainly aims at four sets of typical operation mode data commonly used by the power grid, and obtains a mode pre-control scheme applicable to most of situations. For the working conditions under the specific operation mode data, the method can also be adopted to obtain a mode pre-control scheme under the specific operation mode data, and the risk under the worst condition needs to be considered generally so as to ensure that the scheme can meet the fault ride-through under the operation mode data.

The invention provides a safe and stable operation mode pre-control method for heavy load of an alternating current/direct current receiving end, which is characterized in that: 1) the characteristic that heavy load is accessed in an alternating current and direct current receiving end area is comprehensively considered, and especially the risk caused by the condition that the load is increased too fast and the construction of a grid structure of a power grid is lagged or the maintenance is carried out is comprehensively considered; 2) direct current power is too high, the load is overweight, and alternating current circuit terminal power supports weakly, leads to the stability problem to appear after the multifactor coupling easily, need comprehensive consideration and formulate the safe and stable operation mode and control in advance.

The scheme of this application has following beneficial effect: by formulating a safe and stable operation mode pre-control method, the safety and stability of regional power grid operation are effectively improved, the influence of faults on the access of an alternating current receiving end and a direct current receiving end to a heavy load region is reduced, the safe and stable operation of the power grid is ensured, and the conditions of large influences such as direct current blocking, alternating current system voltage collapse and the like caused by faults are avoided.

Fig. 2 is a block diagram illustrating a configuration of a pre-control device for a safe and stable operation mode of a power grid according to an exemplary embodiment. Referring to fig. 2, the apparatus includes:

With regard to the apparatus in the above embodiment, the specific steps in which the respective modules perform operations have been described in detail in the embodiment related to the method, and are not described in detail herein. The modules in the above-mentioned precontrol device can be realized by software, hardware and their combination in whole or in part. The modules can be embedded in a hardware form or independent from a processor in the computer device, and can also be stored in a memory in the computer device in a software form, so that the processor can call and execute operations corresponding to the modules.

It is understood that the same or similar parts in the above embodiments may be mutually referred to, and the same or similar parts in other embodiments may be referred to for the content which is not described in detail in some embodiments.

It should be noted that, in the description of the present application, the terms "first", "second", etc. are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. Further, in the description of the present application, the meaning of "a plurality" means at least two unless otherwise specified.

Any process or method descriptions in flow charts or otherwise described herein may be understood as representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or steps of the process, and the scope of the preferred embodiments of the present application includes other implementations in which functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art of the present application.

It should be understood that portions of the present application may be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, the various steps or methods may be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, any one or combination of the following techniques, which are known in the art, may be used: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application specific integrated circuit having an appropriate combinational logic gate circuit, a Programmable Gate Array (PGA), a Field Programmable Gate Array (FPGA), or the like.

It will be understood by those skilled in the art that all or part of the steps carried by the method for implementing the above embodiments may be implemented by hardware related to instructions of a program, which may be stored in a computer readable storage medium, and when the program is executed, the program includes one or a combination of the steps of the method embodiments.

In addition, functional units in the embodiments of the present application may be integrated into one processing module, or each unit may exist alone physically, or two or more units are integrated into one module. The integrated module can be realized in a hardware mode, and can also be realized in a software functional module mode. The integrated module, if implemented in the form of a software functional module and sold or used as a separate product, may also be stored in a computer-readable storage medium.

The storage medium mentioned above may be a read-only memory, a magnetic or optical disk, etc.

In the description herein, reference to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the application. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Although embodiments of the present application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present application, and that variations, modifications, substitutions and alterations may be made to the above embodiments by those of ordinary skill in the art within the scope of the present application.

Claims

1. A pre-control method for a safe and stable operation mode of a power grid is characterized by comprising the following steps:

2. The method of claim 1, wherein the predetermined operational data is typical annual operational mode data;

3. The method of claim 1, wherein determining all risks in the operating mode comprises:

the risks in each mode of operation are numbered separately.

4. The method of claim 1, wherein the risk comprises at least one of: n-1 fault, N-2 fault, N-1 fault in maintenance mode, and N-2 fault in maintenance mode.

5. The method according to any one of claims 1 to 4, wherein the simulating development of the grid safe and stable operation mode pre-control comprises:

6. The method of claim 5, wherein the stability criterion comprises at least one of: the line or the main transformer is not overloaded, the power angle is not unstable, the steady-state voltage of the system is not unstable, the steady-state frequency of the system is not unstable, the transient voltage of the system is not unstable, the direct current is not locked, and the frequency of the direct current commutation failure is not more than a preset threshold value.

7. The method of claim 6, wherein the performing a simulation test on the fault corresponding to each risk under the condition of the dc outage comprises:

8. The method of claim 7, wherein performing simulation tests on the faults corresponding to the risks under the condition of recovering the direct current operation comprises:

9. The method of claim 8, wherein the determining the corresponding pre-control parameters according to the simulation pre-control result comprises:

10. The utility model provides a pre-control device of electric wire netting safety and stability operational mode which characterized in that includes: