A voltage control method for coordinating new energy and a collection station

Abstract

The application provides a voltage control method of new energy and a gathering station, which comprises the following steps: acquiring super-short-term power prediction data of all new energy field stations in a new energy gathering area and performing difference interpolation to obtain new energy field station power prediction data with an interval of 5 minutes; when a control period arrives, using the new energy field station power prediction data with an interval of 5 minutes, point-by-point summation is performed on power prediction data of all new energy field stations in the new energy gathering area in the future 15 minutes to form a power prediction trend of the new energy gathering station; and according to the power prediction trend, the reactive power compensation of the gathering station is increased or decreased in advance to realize voltage control of the new energy gathering area. The application uses the reactive power regulation capacity of the gathering station to raise or lower the voltage level of the new energy gathering area in advance to meet the safety requirement of new energy voltage control.

Description

Technical Field

[0001] This invention belongs to the field of automatic voltage control technology for power systems, and specifically relates to a voltage control method for coordinating new energy sources and collecting stations. Background Technology

[0002] Automatic Voltage Control (AVC) systems are an important means of achieving safe (improving voltage stability margin), economical (reducing network losses), and high-quality (improving voltage qualification rate) operation of the power grid. Its basic principle is to achieve a reasonable distribution of reactive voltage in the power grid by coordinating and controlling the reactive power output of generators, transformer taps, and reactive power compensation equipment.

[0003] To date, there are three main modes of automatic voltage control worldwide:

[0004] The first approach, represented by the German power company RWE, involves two-level control without any regional control. The optimal power flow (OPF) calculation results are directly sent to the primary voltage controllers of each power plant for control. However, the OPF model involves a large amount of computation and takes a long time. When large disturbances, sudden increases or decreases in load occur in the system, if the system relies entirely on OPF, the response speed of the AVC (Automatic Voltage Controller) will be insufficient, and the dynamic quality of the control will be difficult to guarantee.

[0005] The second type is the three-level voltage control mode developed by EDF in France. Research and implementation of this mode began in the 1970s, and after more than 30 years of research, development, and application, it is currently recognized internationally as the most advanced voltage control system. While this control mode has been well-appointed, it still has drawbacks. This is because the regional two-level voltage control (SVC) is developed based on the locality of reactive voltage in the power system. However, reactive voltage is coupled between regions, so the quality of the control system fundamentally depends on the degree of coupling between reactive voltage controls in each region. However, with the development of the power system and the real-time changes in operating conditions, the regions that were initially considered relatively decoupled are not static. Furthermore, the control sensitivity, which exists in the form of fixed control parameters, changes in real-time with operating conditions. Therefore, this type of fixed-hardware regional controller is difficult to adapt to the continuous development of the power system and the significant changes in real-time operating conditions, making it difficult to consistently guarantee good control performance.

[0006] The third approach is a three-level voltage control mode based on "soft partitioning," proposed by the Dispatch Automation Laboratory of the Department of Electrical Engineering at Tsinghua University. This mode overcomes the shortcomings of hard partitioning in the EDF three-level voltage control system through soft partitioning. It has been widely applied in more than 20 regional and provincial power grids in China and has been successfully extended to the voltage control of the PJM power grid in North America. In this mode, the AVC application software in the dispatch center consists of a three-level control module and a two-level control module. The three-level control is the optimal power flow (OPF) for global reactive power optimization, providing a coordinated voltage optimization control objective for the entire network. The two-level control is the calculation of decoupled control strategies for each partition. Taking the optimized control objective of the central bus in each partition given by the three-level control as input, it considers reactive power regulation equipment such as power plants within the partition, calculates the control strategies for various reactive power resources within the partition, and distributes them to power plants and substations. The substation devices at the plant and substation ends complete the first-level control, receiving and executing the control strategies issued by the dispatch master station. Currently, automatic voltage control software developed using this mode is widely used in my country, installed and deployed in provincial and regional power grid dispatch control centers to automatically control voltage and reactive power at various voltage levels in the power grid.

[0007] Large-scale wind turbine grid disconnection accidents caused by voltage problems occur frequently. Post-accident analysis reveals that they all follow a similar development process: First, under conditions of high regional wind power generation, the transmission lines consume a large amount of reactive power, resulting in a low overall regional voltage level. Then, due to a sudden disturbance in the system (sometimes a fault), some wind farms disconnect from the grid due to low voltage or enter a low-voltage ride-through state. After the disturbance (fault) is cleared, the power of the transmission lines drops instantaneously due to the disconnection of multiple wind turbines or their entry into the low-voltage ride-through state. Under the combined effect of the unloaded line capacity rise effect and the capacitor banks that were previously connected to the grid under heavy load, the regional voltage spikes, causing wind turbines in other wind farms, as well as those that have just recovered from the low-voltage ride-through state, to disconnect from the grid due to high voltage. Ultimately, this chain reaction causes hundreds of wind turbines in the wind power area to disconnect from the grid on a large scale.

[0008] Therefore, how to develop a voltage control method that coordinates new energy sources and collection stations, analyzes the power trend of the new energy collection area based on new energy power prediction data before an accident occurs, fully explores the reactive power regulation capacity of the new energy collection area, especially the collection station, and meets the voltage operation requirements of the new energy collection area is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0009] The purpose of this invention is to overcome the shortcomings of existing technologies and propose a voltage control method that coordinates new energy sources with collection stations. This invention utilizes the reactive power regulation capability of collection stations to raise or lower the overall voltage level of the new energy collection area in advance, thereby meeting the safety requirements of new energy voltage control.

[0010] This invention proposes a voltage control method for coordinating new energy sources and collection stations, comprising:

[0011] The ultra-short-term power prediction data of all new energy power stations in the new energy gathering area were obtained and interpolated by equal arithmetic to obtain the power prediction data of new energy power stations at 5-minute intervals.

[0012] When the control cycle arrives, the power prediction data of the new energy power stations with a 5-minute interval is used to sum the power prediction data of all new energy power stations in the new energy aggregation area for the next 15 minutes point by point to form the power prediction trend of the new energy aggregation station.

[0013] Based on the power prediction trend, voltage control of the new energy aggregation area can be achieved by increasing or decreasing the reactive power compensation of the aggregation station in advance.

[0014] In one specific embodiment of the present invention, it further includes:

[0015] The ultra-short-term power prediction data for the new energy power plants are as follows:

[0016]

[0017] in, The first in the new energy gathering area New energy power stations from the current moment Start of The total active power after minutes, with a time interval of 15 minutes; The number of new energy power stations in the new energy aggregation area; T is the time of the last predicted value of the ultra-short-term forecast data.

[0018] By performing arithmetic interpolation on the ultra-short-term power prediction data, we obtain:

[0019]

[0020] in, The first new energy gathering area after arithmetic interpolation New energy power stations from the current moment Start of Total active power after minutes.

[0021] In one specific embodiment of the present invention, the formation of the power prediction trend of the new energy collection station includes:

[0022] All new energy stations within the new energy aggregation area The power prediction data at each time point are summed to calculate the power prediction for the renewable energy collection station:

[0023]

[0024] in, Indicates new energy gathering station Power prediction data at any given time;

[0025] Based on the power prediction of the renewable energy collection station, the trend of power prediction is judged:

[0026]

[0027] in, Indicates the trend of power prediction. Indicates an upward trend. This indicates a downward trend. This represents the percentage threshold for changes in adjacent power prediction points.

[0028] 4. The method according to claim 3, characterized in that it further comprises:

[0029] like This reduces reactive power compensation at the collection station;

[0030] Wherein, let:

[0031]

[0032] in, This refers to the upper limit of the voltage on the high-voltage side bus of the collecting station. For the current voltage measurement of the high-voltage side bus of the collection station, This is the dead zone coefficient. ;

[0033] Will The data is sent to the master station AVC control module. When the master station AVC control module calculates the control strategy, in order to eliminate the voltage over-limit of the high-voltage side bus of the collection station, it disconnects the low-voltage side capacitor of the collection station or connects the low-voltage side reactor of the collection station without causing the load bus to over-limit, thereby reducing the reactive power compensation of the collection station.

[0034] like This would increase the reactive power compensation at the collection station;

[0035] Wherein, let:

[0036]

[0037] in, This is the lower limit of the voltage on the high-voltage side bus of the collecting station; The data is sent to the master station AVC control module. When the master station AVC control module calculates the control strategy, in order to eliminate the voltage of the high-voltage side bus of the collection station from falling below the lower limit, it will either put the low-voltage side capacitor of the collection station into operation or disconnect the low-voltage side reactor of the collection station without causing the load bus to fall below the upper limit, thereby increasing the reactive power compensation of the collection station.

[0038] The features and beneficial effects of this invention are as follows:

[0039] This invention proposes a voltage control method for coordinating new energy sources and power collection stations, belonging to the field of automatic voltage control technology for power systems. The method includes: when a data acquisition cycle arrives, acquiring ultra-short-term power prediction data for all new energy power stations within the new energy collection area and performing arithmetic interpolation. When a control cycle arrives, summing the power prediction data for the next 15 minutes for all new energy power stations within the collection area point by point to form a power prediction trend for the new energy collection stations. Based on this power prediction trend, increasing or decreasing reactive power compensation at the collection stations in advance. This invention utilizes the reactive power regulation capability of the collection stations to raise or lower the overall voltage level of the new energy collection area in advance, thereby meeting the safety requirements of new energy voltage control. Attached Figure Description

[0040] Figure 1 This is a flowchart illustrating a voltage control method for coordinating new energy sources and a collection station, according to an embodiment of the present invention.

[0041] Figure 2 This is a structural diagram of a new energy collection area according to a specific embodiment of the present invention. Detailed Implementation

[0042] This invention proposes a voltage control method for coordinating new energy sources and collection stations, which is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0043] This embodiment proposes a voltage control method for coordinating new energy sources and collection stations, including:

[0044] The ultra-short-term power prediction data of all new energy power stations in the new energy gathering area were obtained and interpolated by equal arithmetic to obtain the power prediction data of new energy power stations at 5-minute intervals.

[0045] When the control cycle arrives, the power prediction data of the new energy power stations with a 5-minute interval is used to sum the power prediction data of all new energy power stations in the new energy aggregation area for the next 15 minutes point by point to form the power prediction trend of the new energy aggregation station.

[0046] Based on the power prediction trend, voltage control of the new energy aggregation area can be achieved by increasing or decreasing the reactive power compensation of the aggregation station in advance.

[0047] In one specific embodiment of the present invention, the voltage control method for coordinating new energy sources and collection stations has the following overall process: Figure 1 As shown, it includes the following steps:

[0048] 1) Obtain ultra-short-term power prediction data of all new energy power stations in the new energy aggregation area and perform arithmetic interpolation to obtain power prediction data of new energy power stations at 5-minute intervals.

[0049] In this embodiment, when the data acquisition period arrives (generally 15 minutes in this embodiment), the ultra-short-term power prediction data of the renewable energy power station is obtained as follows:

[0050]

[0051] in, The first in the new energy gathering area New energy power stations from the current moment Start of The total active power after minutes, with a time interval of 15 minutes; , represents the number of new energy power stations in the new energy aggregation area; T represents the time of the last predicted value of the ultra-short-term forecast data.

[0052] By performing arithmetic interpolation on the ultra-short-term power prediction data, we obtain:

[0053]

[0054] in, The first new energy gathering area after arithmetic interpolation New energy power stations from the current moment Start of The total active power after 5 minutes is recorded.

[0055] 2) When the control cycle arrives, based on the power prediction data obtained by arithmetic interpolation in step 1), the power prediction data of all new energy stations in the new energy aggregation area for the next 15 minutes are summed point by point to form the power prediction trend of the new energy aggregation station.

[0056] In this embodiment, when the control cycle arrives (generally 5 minutes in this embodiment), the power prediction of the new energy collection station for the next 15 minutes is as follows:

[0057]

[0058] in, Indicates new energy gathering station Power prediction data at any given time.

[0059] Based on the power prediction of the renewable energy collection station, the trend of power prediction is judged:

[0060]

[0061] in Indicates the trend of power prediction. Indicates an upward trend. This indicates a downward trend. This represents the percentage threshold for changes between adjacent power prediction points (typically 2% in this embodiment). Starting from the current moment, if the values ​​of the two most recent power prediction points are both greater than the value of the previous power prediction point, and their percentage changes are greater than the threshold, then the power prediction point is considered to have changed. This means that the power output of the new energy region will increase rapidly, and vice versa.

[0062] 3) Based on the results of step 2), increase or decrease the reactive power compensation of the collection station in advance according to the trend of power prediction.

[0063] In this embodiment, if This reduces reactive power compensation at the collection station. Let:

[0064]

[0065] in This refers to the upper limit of the voltage on the high-voltage side bus of the collecting station. For the current voltage measurement of the high-voltage side bus of the collection station, The dead zone coefficient is set manually. .Will Sending to the main station AVC control module, because When the main station AVC control module calculates the control strategy, in order to eliminate the voltage of the high-voltage side bus of the collection station from exceeding the upper limit, it will disconnect the low-voltage side capacitor of the collection station or connect the low-voltage side reactor of the collection station without causing the load bus to exceed the lower limit, thereby reducing the reactive power compensation of the collection station.

[0066] like This would increase the reactive power compensation at the collection station. Let:

[0067]

[0068] in This is the lower limit of the voltage on the high-voltage side bus of the collecting station. Sending to the main station AVC control module, because When the main station AVC control module calculates the control strategy, in order to eliminate the voltage of the high-voltage side bus of the collection station from falling below the lower limit, it will activate the low-voltage side capacitor of the collection station or disconnect the low-voltage side reactor of the collection station without causing the load bus to fall below the upper limit, thereby increasing the reactive power compensation of the collection station.

[0069] The method described in this embodiment will be further explained in detail below with reference to a specific example:

[0070] A specific embodiment of the present invention is a 220kV renewable energy collection area, with the structure as follows: Figure 2 As shown, it includes: 1 220kV substation, 2 new energy power stations, and a total of 5 equivalent generators.

[0071] In this embodiment, the data acquisition cycle is set to 15 minutes, and the control cycle is set to 5 minutes. In this embodiment, the voltage control method for coordinating new energy sources and the collection station includes the following steps:

[0072] 1) When the data collection period arrives, acquire ultra-short-term power prediction data for two renewable energy power plants:

[0073]

[0074]

[0075] right and By performing arithmetic interpolation, we obtained power prediction data for new energy power plants at 5-minute intervals:

[0076]

[0077]

[0078] 2) When the control cycle arrives, based on the power prediction data obtained by arithmetic interpolation in step 1), the power prediction data of all new energy stations in the new energy aggregation area for the next 15 minutes are summed point by point to form the power prediction trend of the new energy aggregation station.

[0079] In this embodiment, the power prediction of the new energy aggregation station for the next 15 minutes is as follows:

[0080]

[0081] set up The trend of power prediction is obtained:

[0082]

[0083]

[0084]

[0085] 3) Based on the results of step 2), increase or decrease the reactive power compensation of the collection station in advance according to the trend of power prediction.

[0086] In this embodiment, let

[0087] because ,set up This constraint is sent to the main station AVC control module to achieve the effect of reducing the overall reactive power of the new energy aggregation area in advance.

[0088] The technical solutions provided by the embodiments of the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the embodiments of the present invention. The descriptions of the embodiments above are only for helping to understand the principles of the embodiments of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the embodiments of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A voltage control method for coordinating new energy sources and a collection station, characterized in that, include: The ultra-short-term power prediction data of all new energy power stations in the new energy gathering area were obtained and interpolated by equal arithmetic to obtain the power prediction data of new energy power stations at 5-minute intervals. When the control cycle arrives, the power prediction data of the new energy power stations with a 5-minute interval is used to sum the power prediction data of all new energy power stations in the new energy aggregation area for the next 15 minutes point by point to form the power prediction trend of the new energy aggregation station. Based on the power prediction trend, voltage control of the new energy aggregation area can be achieved by increasing or decreasing the reactive power compensation of the aggregation station in advance.

2. The method according to claim 1, characterized in that, Also includes: The ultra-short-term power prediction data for the new energy power plants are as follows: in, The first in the new energy gathering area New energy power stations from the current moment Start of The total active power after minutes, with a time interval of 15 minutes; The number of new energy power stations in the new energy aggregation area; T is the time of the last predicted value of the ultra-short-term forecast data. By performing arithmetic interpolation on the ultra-short-term power prediction data, we obtain: in, The first new energy gathering area after arithmetic interpolation New energy power stations from the current moment Start of Total active power after minutes.

3. The method according to claim 2, characterized in that, The power prediction trend for the formation of new energy collection stations includes: All new energy stations within the new energy aggregation area The power prediction data at each time point are summed to calculate the power prediction for the renewable energy collection station: in, Indicates new energy gathering station Power prediction data at any given time; Based on the power prediction of the renewable energy collection station, the trend of power prediction is judged: in, Indicates the trend of power prediction. Indicates an upward trend. This indicates a downward trend. This represents the percentage threshold for changes in adjacent power prediction points.

4. The method according to claim 3, characterized in that, Also includes: like This reduces reactive power compensation at the collection station; Wherein, let: in, This refers to the upper limit of the voltage on the high-voltage side bus of the collecting station. For the current voltage measurement of the high-voltage side bus of the collection station, This is the dead zone coefficient. ; Will The data is sent to the master station AVC control module. When the master station AVC control module calculates the control strategy, in order to eliminate the voltage over-limit of the high-voltage side bus of the collection station, it disconnects the low-voltage side capacitor of the collection station or connects the low-voltage side reactor of the collection station without causing the load bus to over-limit, thereby reducing the reactive power compensation of the collection station. like This would increase the reactive power compensation at the collection station; Wherein, let: in, This is the lower limit of the voltage on the high-voltage side bus of the collecting station; The data is sent to the master station AVC control module. When the master station AVC control module calculates the control strategy, in order to eliminate the voltage of the high-voltage side bus of the collection station from falling below the lower limit, it will either put the low-voltage side capacitor of the collection station into operation or disconnect the low-voltage side reactor of the collection station without causing the load bus to fall below the upper limit, thereby increasing the reactive power compensation of the collection station.

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