Stable control method and system for inhibiting repeated voltage ride through of new energy station

Abstract

The invention discloses a stability control method and system for inhibiting repeated voltage ride through of a new energy station, and relates to the field of power grid safety and stability control. Calculating the static stability limit of the system in real time according to the collected data; when a tripping event occurs in the line, calculating the switching amount based on the static stability limit of the system; and performing output removal on the new energy station according to the required removal amount. The static stability limit of the system is automatically calculated through line parameters, a stability control measure of active oscillation suppression is adopted based on fault driving, a generator tripping measure considering fairness and a control effect is adopted according to new energy output, and the control method is simple and reliable, can be widely applied to a new energy centralized grid-connected area, and has wide application prospects. And reliable and stable operation of the new energy centralized grid-connected regional power grid is ensured.

Description

Technical Field

[0001] The present invention relates to the field of safe and stable control of power grids, and in particular to a stable control method and system for suppressing repeated voltage ride-through at a new energy station. Background Art

[0002] With the construction of new power systems, the proportion of wind and solar power in the system continues to increase, and some areas are gradually dominated by wind and solar power. Compared with the transmission of traditional power sources, the regional stability characteristics have undergone profound changes. The distance of the new energy collection and transmission lines is long, the grid structure is relatively weak and lacks voltage support, showing significant weak grid characteristics, which easily leads to voltage and oscillation stability problems in the new energy collection area. Among them, photovoltaic stations in the southern region occasionally have a new stability problem of repeated fluctuations in active power, causing photovoltaic disconnection in the area and short-term low-frequency oscillation information alarms for large units in the vicinity, affecting the normal and stable operation of the region. Traditional stability control methods mostly use the method of detecting overload of the remaining lines to cut off the new energy station units. Due to large power fluctuations, the overload action criteria may not be met, the stability control strategy refuses to operate, and the system becomes unstable.

[0003] This paper proposes a method to suppress repeated voltage crossing in renewable energy stations. By designing a targeted stability control strategy in the regional transmission stability control system and changing the overload detection method to the section detection method, power fluctuations can be effectively suppressed to maintain safe and stable operation of the power grid. Summary of the invention

[0004] In view of the above-mentioned problems, the present invention is proposed.

[0005] Therefore, the problem to be solved by the present invention is that traditional stability control methods mostly use the method of detecting overload of remaining lines to cut off the new energy station units. Due to large power fluctuations, the overload action criterion may not be met, the stability control strategy refuses to work, and the system becomes unstable.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: a stable control method for suppressing repeated voltage crossing of new energy stations, which includes collecting power data of regional transmission lines; calculating the system static stability limit in real time according to the collected data; when a line tripping event occurs, calculating the required cutting amount based on the system static stability limit; and cutting off the output of the new energy station according to the required cutting amount.

[0007] As a preferred solution of the stable control method for suppressing repeated voltage crossing of new energy stations described in the present invention, the power data of the regional transmission lines collected include the voltage and current of the transmission lines, and the power and line impedance parameters are calculated; the real-time power generation output information of the regional new energy stations is obtained from the dispatching control system to determine the strategy execution object.

[0008] As a preferred solution of the stability control method for suppressing repeated voltage ride-through of a new energy station described in the present invention, the real-time calculation of the system static stability limit includes, for a single new energy power station, the system static stability limit Pmax It is expressed as,

[0009]

[0010] in, Us is the grid-connected output point voltage, Xs is the output line impedance, Sac It is the short-circuit capacity of the photovoltaic power station grid connection point.

[0011] As a preferred solution of the stability control method for suppressing repeated voltage ride-through of a new energy station described in the present invention, the real-time calculation system static stability limit also includes, when the object is multiple new energy power stations, calculating the upper limit of the capacity sent by the new energy collection area according to the transmission line respectively. Pmax1 , Pmax2 ,…… Pmaxn , then considering a certain margin ks In the case of Psoc It is expressed as,

[0012] P soc =min{P max1 ,P max2 ,......,P maxn}×k s .

[0013] As a preferred solution of the stability control method for suppressing repeated voltage crossing of a new energy station described in the present invention, wherein: when a line trips, the required shearing capacity is calculated based on the system static stability limit, including: when more than two outgoing lines trip and only a single line is left for regional outgoing, the outgoing section power before the accident is locked in the device Pm Calculate the amount of cutting required Pc It is expressed as,

[0014]

[0015] in, kc is the control coefficient; the judgment criterion for the line tripping is that the current and power suddenly change to 0, and the line switch position satisfies the three-phase from 1→0.

[0016] As a preferred scheme of the stable control method for suppressing repeated voltage crossing of new energy stations described in the present invention, wherein: the output cutting of new energy stations according to the required cutting amount includes selecting the new energy stations in order from large to small output, and cutting the output of each station by station according to the method of cutting s% of the output; the s is set according to the required cutting amount.

[0017] Another object of the present invention is to provide a stable control system for suppressing repeated voltage crossing of new energy stations. This system can calculate the output cut-off amount of the new energy station based on the collected power data to suppress power fluctuations and maintain safe and stable operation of the power grid.

[0018] To solve the above technical problems, the present invention provides the following technical solutions: a system for a stable control method for suppressing repeated voltage crossing of a new energy station, comprising: an acquisition module, a system static stability limit calculation module, a control strategy module and a control quantity allocation module; the acquisition module acquires power data of regional transmission lines; the system static stability limit calculation module calculates the system static stability limit in real time according to the collected data; when a line trips, the control strategy module calculates the required cut-off based on the system static stability limit; the control quantity allocation module performs output cut-off for the new energy station according to the required cut-off.

[0019] A computer device includes a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the steps of a stable control method for suppressing repeated voltage crossing of a new energy station as described above are implemented.

[0020] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of a stable control method for suppressing repeated voltage crossing of a new energy station as described above.

[0021] The beneficial effects of the present invention are as follows: Traditional stability control methods mostly use the method of detecting the overload of the remaining lines to cut off the renewable energy station units. Due to the large power fluctuations, the overload action criterion may not be met, the stability control strategy refuses to work, and the system becomes unstable. The present invention automatically calculates the system static stability limit through line parameters, takes active oscillation suppression stability control measures based on fault drive, and takes cutting measures that take into account fairness and control effects according to the output of renewable energy. The control method is simple and reliable, and can be widely used in the concentrated grid-connected areas of renewable energy, ensuring the reliable and stable operation of the power grid in the concentrated grid-connected areas of renewable energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. Among them:

[0023] Figure 1 This is a scenario diagram of a stabilization control method for suppressing repeated voltage ride-through in a new energy station in Example 1.

[0024] Figure 2This is a structural diagram of a stabilization control method for suppressing repeated voltage ride-through in a new energy station in Example 2.

[0025] Figure 3 This is a structural diagram of the first support unit of a stable control method for suppressing repeated voltage crossing in a new energy station in Example 2.

[0026] Figure 4 This is another perspective view of the first support unit of a stable control method for suppressing repeated voltage crossing of a new energy station in Example 2.

[0027] Figure 5 This is a module structure diagram of a stable control system for suppressing repeated voltage ride-through in a new energy station in Example 3. DETAILED DESCRIPTION

[0028] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0029] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0030] Example 1, reference Figure 1 , which is the first embodiment of the present invention, and which provides a stable control method for suppressing repeated voltage ride-through of a new energy station, including: Figure 1 As shown:

[0031] S1. Collect power data of regional transmission lines.

[0032] The power data of the transmission lines in the collection area include the voltage, current, calculated power and line impedance parameters of the transmission lines.

[0033] Obtain real-time power generation output information of regional new energy stations from the dispatching and control system to determine the strategy execution objects.

[0034] S2. Calculate the system static stability limit in real time based on the collected data.

[0035] For a single renewable energy power station, the system static stability limit Pmax It is expressed as,

[0036]

[0037] in, Us is the grid-connected output point voltage, Xs is the output line impedance, SacIt is the short-circuit capacity of the photovoltaic power station grid connection point. At this time, the system static stability limit is about 0.5 times the short-circuit capacity of the new energy station.

[0038] When the object is multiple new energy power stations, calculate the upper limit of the capacity sent by the new energy gathering area according to the transmission lines. Pmax1 , Pmax2 ,…… Pmaxn , then considering a certain margin ks In the case of Psoc It is expressed as,

[0039] P soc =min{P max1 ,P max2 ,......,P maxn}×k s .

[0041] S3. When a line trip occurs, the required cutting capacity is calculated based on the system static stability limit.

[0042] When more than two outgoing lines trip and only one outgoing line is left in the area, the outgoing section power before the accident stored in the device is Pm Calculate the amount of cutting required Pc It is expressed as,

[0043]

[0044] in, kc is the control coefficient.

[0045] The judgment criteria for line tripping are that the current and power suddenly change to 0, and the line switch position satisfies the three-phase change from 1→0.

[0046] S4. Cut off the output of new energy stations according to the required cutting amount.

[0047] Select the new energy stations in order of output from large to small, and cut off s% of the output of each station in rotation, so as to effectively avoid section power oscillation caused by excessive power of a single station. s is set according to the required cutting amount.

[0048] Example 2, reference Figure 2-Figure 4 , which is the second embodiment of the present invention, and is different from the first embodiment in that: a stable control method for suppressing repeated voltage ride-through of a new energy station also includes, in order to verify and illustrate the technical effect adopted in this method, this embodiment adopts a traditional technical solution and the method of the present invention for comparative testing, and compares the test results by means of scientific demonstration to verify the real effect of this method.

[0049] The schematic diagram of the primary grid system in a new energy collection area is as follows: Figure 2As shown. Eight new energy stations including U11-U18 are sent to U21 station through 220kV lines L1, L2 and L3 and connected to the 500kV main grid. When L2 and L3 lines trip at the same time, the new energy units of U11, U12 and U13 frequently cross, and the system power oscillates greatly. The original strategy for detecting L1 line overload cannot continuously meet the overload setting value (400MW) and refuses to operate. Figure 3 shown.

[0050] Therefore, a new control strategy is designed based on the present invention:

[0051] (1) Calculation of system static stability limit value:

[0052] Obtain the line length parameters and calculate the static stability limit of the system when the line L1-L5 is running as a single line, referring to the impedance of the LGJ-400 conductor of 0.28Ω per km, as shown in Table 1:

[0053] Table 1: Line Static Stability Limit Table

[0054] line Line length / km Impedance / Ω Pmax / MW L1 58 16.24 496.7 L2 33 9.24 873.0 L3 34 9.52 847.3 L4 41 11.48 702.7 L5 41 11.48 702.7

[0055] make ks Take 0.8, and we get Psoc =496.7×0.8≈400MW.

[0056] (2) Control strategy:

[0057] Based on real-time simulation system Figure 2 The primary power grid, before the accident, the transmission section power composed of L1, L2, and L3 was 650MW;

[0058] The real-time simulator simulates the tripping of lines L2 and L3. Station U21 detects that the current and power of lines L2 and L3 suddenly change to 0. At the same time, the line switch position satisfies the three-phase transition from 1 to 0, and the line is judged to be tripped.

[0059] Assume control coefficient kc If the value is 1.2, the required cutting amount Pc =300MW.

[0060] (3) Control quantity allocation: According to simulation analysis, the greater the output of the renewable energy station, the more likely it is to exceed the static stability limit, resulting in system power fluctuations. The output of renewable energy stations U11-U18 before the accident is sorted. The outputs of U13, U15, and U16 with larger outputs are all 250MW. If each station is selected to cut the generator in turn at 50% capacity, then U13, U15, and U16 are selected to cut 125MW each. After cutting the generator, the system and the remaining renewable energy units maintain stable operation. Figure 4 shown.

[0061] In summary, the method for suppressing repeated voltage crossing of renewable energy stations proposed in the present invention is simple and reliable, can adaptively calculate the static stability limit of the system, and take active oscillation suppression measures based on fault drive, thereby ensuring the reliable and stable operation of the power grid in the area where renewable energy is concentrated and connected to the grid.

[0062] Example 3, reference Figure 5 , which is the third embodiment of the present invention, and is different from the previous two embodiments in that: a system of a stability control method for suppressing repeated voltage ride-through of a new energy station comprises a collection module 100, a system static stability limit calculation module 200, a control strategy module 300 and a control quantity allocation module 400; the collection module 100 collects power data of regional transmission lines; the system static stability limit calculation module 200 calculates the system static stability limit in real time according to the collected data; when a line tripping event occurs, the control strategy module 300 calculates the required cut-off quantity based on the system static stability limit; the control quantity allocation module 400 performs output cut-off of the new energy station according to the required cut-off quantity.

[0063] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc., which can store program codes.

[0064] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in conjunction with such instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in conjunction with such instruction execution systems, devices or apparatuses.

[0065] More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic device), a portable computer disk case (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be a paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering or, if necessary, processing in another suitable manner, and then stored in a computer memory.

[0066] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0067] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A stable control method for suppressing repeated voltage ride-through in a new energy station, characterized in that: include, Collect power data of regional transmission lines; Calculate the system static stability limit in real time based on the collected data; When a line trips, the required shedding capacity is calculated based on the system static stability limit; The output of new energy stations is cut according to the required output.

2. A stable control method for suppressing repeated voltage ride-through of a new energy station as claimed in claim 1, characterized in that: The power data of the transmission line in the acquisition area includes the voltage and current of the transmission line, the calculated power and the line impedance parameters; Obtain real-time power generation output information of regional new energy stations from the dispatching and control system to determine the strategy execution objects.

3. A stable control method for suppressing repeated voltage ride-through of a new energy station as claimed in claim 2, characterized in that: The real-time calculation of the system static stability limit includes, for a single new energy power station, the system static stability limit Pmax It is expressed as, in, Us is the grid-connected output point voltage, Xs is the output line impedance, Sac It is the short-circuit capacity of the photovoltaic power station grid connection point.

4. A stable control method for suppressing repeated voltage ride-through of a new energy station as claimed in claim 3, characterized in that: The real-time calculation of the system stability limit also includes, when the object is multiple new energy power stations, calculating the upper limit of the capacity sent by the new energy collection area according to the transmission lines respectively. Pmax1 , Pmax2 ,…… Pmaxn , then considering a certain margin ks In the case of Psoc It is expressed as, P soc =min{P max1 ,P max2 ,......,P maxn }×k s 。 5. A stable control method for suppressing repeated voltage ride-through of a new energy station as claimed in claim 4, characterized in that: When a line trips, the required shedding is calculated based on the system static stability limit, including: when more than two outgoing lines trip and only one outgoing line is left in the area, the outgoing section power before the accident is locked in the device. Pm Calculate the amount of cutting required Pc It is expressed as, in, kc is the control coefficient; The judgment criterion for line tripping is that the current and power suddenly change to 0, and the line switch position satisfies the three-phase change from 1 to 0.

6. A stable control method for suppressing repeated voltage ride-through of a new energy station as claimed in claim 5, characterized in that: The output cutting of the new energy stations according to the required cutting amount includes selecting the new energy stations in order of output from large to small, and cutting the output of each station by s% in rotation; The s is set according to the required cutting amount.

7. A system using a stable control method for suppressing repeated voltage ride-through of a new energy station as claimed in any one of claims 1 to 6, characterized in that: It comprises a collection module (100), a system static stability limit calculation module (200), a control strategy module (300) and a control quantity allocation module (400); The collection module (100) collects power data of the regional transmission line; The system static stability limit calculation module (200) calculates the system static stability limit in real time according to the collected data; When a line trip event occurs, the control strategy module (300) calculates the required cutting quantity based on the system static stability limit; The control quantity allocation module (400) performs output cutting on the new energy station according to the required cutting quantity.

8. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of a stable control method for suppressing repeated voltage ride-through of a new energy station as described in any one of claims 1 to 6 are implemented.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of a stable control method for suppressing repeated voltage ride-through of a new energy station as described in any one of claims 1 to 6 are implemented.

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