Offshore wind power booster station load control system and method based on hierarchical protection

Abstract

The present invention relates to a load control system and method for an offshore wind power booster station based on hierarchical protection. The spatial configuration of the system is a local layer, a station area layer and a wide area layer, wherein the local layer is connected to the station area layer by communication, and the station area layer is connected to the wide area layer by communication; the local layer has an intelligent local protection measurement and control device, the station area layer has a station area protection and load control device, and the wide area layer has a line load overload monitoring device, wherein: the line load overload monitoring device is used to monitor the line overload state; the intelligent local protection measurement and control device is used to obtain the real-time power of each wind turbine collection line in real time, and upload it to the station area protection and load control device; the station area protection and load control device is used to select the wind turbine collection line unit with reduced output according to the reduced output signal, the real-time power of each wind turbine collection line combined with the control strategy table, and send a machine cut-off signal to the corresponding intelligent local protection measurement and control device.

Description

Technical Field

[0001] The present invention relates to a load control system and method for an offshore wind power booster station based on hierarchical protection, which is applicable to the technical field of offshore wind power. Background Art

[0002] In recent years, the development of my country's offshore wind power industry has shown an accelerating trend, and the era of offshore wind power bidding and access to the grid is coming. Offshore wind power construction costs and equipment investment are high, and it is very important to improve the efficiency of wind power investment by systematically reducing the cost of key equipment in offshore wind farms. On the other hand, due to the intermittent and volatile characteristics of offshore wind power output, during periods of low load and high wind turbine output, it is also urgent to implement a precise wind turbine removal strategy to ensure the quantitative peak-shaving capacity of the power grid, thereby improving the power grid's ability to absorb offshore wind power. In order to achieve the above goals, improving the intelligence level of secondary equipment, improving the reliability and stability of the device, and reasonably streamlining the configuration of secondary equipment are the current development directions of offshore wind power secondary technology.

[0003] In order to ensure the safe and stable operation of the power grid load, a load control host is usually installed on the system station side where offshore wind power is connected to the power grid. When the host detects that the system line flow exceeds the normal current carrying capacity limit, but does not exceed the line post-accident current carrying capacity limit, it sends a reduction output alarm signal to the load control slave of the wind farm booster station; when it detects that the system line flow exceeds the post-accident current carrying capacity limit, it sends a disconnection signal to the load control slave of the offshore wind farm booster station.

[0004] Generally speaking, the wind power load control of offshore wind power booster stations needs to be achieved by adding separate control equipment, and the control strategy is limited to providing a control method for cutting off the offshore booster transformer. It cannot accurately control the incoming lines of multiple wind turbines. The control strategy is not flexible enough, which is not conducive to improving the load control performance of offshore wind power, and cannot effectively reduce the power loss of wind farms. The power generation efficiency of wind farms cannot be guaranteed. Summary of the invention

[0005] The technical problem to be solved by the present invention is: in view of the above-mentioned problems, a load control system and method for an offshore wind power booster station based on hierarchical protection is provided.

[0006] The technical solution adopted by the present invention is: a load control system for an offshore wind power booster station based on hierarchical protection, characterized in that: the spatial configuration of the system is a local layer, a station area layer and a wide area layer, wherein the local layer is connected to the station area layer by communication, and the station area layer is connected to the wide area layer by communication;

[0007] The local layer has an intelligent local protection measurement and control device, the station area layer has a station area protection and load control device, and the wide area layer has a line load overload monitoring device, wherein:

[0008] The line load overload monitoring device is used to monitor the line overload state, and when a load overload or fault is detected, a power reduction or machine disconnection signal is sent to the station protection and load control device;

[0009] The intelligent local protection and measurement and control device is used to obtain the real-time power of each wind turbine collector line in real time and upload it to the station protection and load control device;

[0010] The station area protection and load control device is used to select the wind turbine collector line unit with reduced output according to the reduced output signal, the real-time power of each wind turbine collector line and the control strategy table, and send a machine cutting signal to the corresponding intelligent local protection measurement and control device;

[0011] The station area protection and load control device is also used to send a machine cutting signal to the intelligent on-site protection and control device corresponding to the step-up transformer with larger output according to the first round of machine cutting signals, and to send a machine cutting signal to the intelligent on-site protection and control devices corresponding to the remaining step-up transformers according to the second round of machine cutting signals.

[0012] The line load overload judgment method of the line load overload monitoring device comprises:

[0013] When the current or power satisfies I ≥ I qd Or P ≥ P qd After that, the time satisfies t≥T qd When the overload start signal is issued;

[0014] After the overload start signal is issued, when the current or power satisfies I≥I qj1 Or P ≥ P qj1 , time satisfies t≥T qj1 When the first round of overload cutting command is issued;

[0015] After the overload start signal is issued, when the current or power satisfies I≥I qj2 Or P ≥ P qj2 , time satisfies t≥T qj2 When the overload is reached, the second round of overload cutting command is issued;

[0016] Where I is the line current collected by the line overload monitoring device, P is the line power calculated by the line overload monitoring device, and I qd is the overload starting current setting, P qd is the overload starting power setting value, Tqd is the overload starting time setting value, I qj1 is the first round of cutting current setting, P qj1 is the power setting value of the first round of cutting, T qj1 is the first round of cutting time setting, I qj2 is the current setting value of the second round of cutting machine, P qj2is the power setting value of the second round of cutting machine, T qj2 Set the time value for the second round of cutting.

[0017] The method of selecting a wind turbine power collection line unit for power reduction according to the power reduction signal, the real-time power of each wind turbine power collection line and the control strategy table includes:

[0018] According to the real-time power P of all fans i , the total amount of load removed P q , combined with the load sensitivity ranking in the control strategy table, determine the fan incoming line units that need to be cut off and the order of cutting off.

[0019] A control method for an offshore wind power booster station load control system based on hierarchical protection, characterized by comprising:

[0020] The station protection and load control device generates a control strategy table. Through online analysis and calculation, according to the wind turbine output and cutting capacity of the intelligent booster station, the cutting queue and cutting object corresponding to the fault type and section power under different operating modes are obtained;

[0021] The intelligent local protection measurement and control device obtains the sampling value and signal quantity data of the fan incoming line interval unit in real time, and uploads it to the station protection and load control device;

[0022] The line load overload monitoring device of the onshore system station determines the line load overload status and line fault status, detects the line load overload or fault according to the line abnormality judgment criteria, and sends a power reduction or machine cutting signal to the station area protection and load control device of the offshore booster station;

[0023] The station protection and load control device detects the reduced output alarm signal issued by the line load overload monitoring device, determines that after receiving the reduced output alarm signal, it obtains the real-time power of each wind turbine collector line, starts the fault judgment and identification method, calculates the reduced output power, queries the control strategy table, selects the reduced output wind turbine collector line unit, and sends a machine cutting signal to the corresponding intelligent local protection measurement and control device;

[0024] The station protection and load control device detects the machine tripping signal issued by the line load overload monitoring device, and after determining that the first round of machine tripping signals are received, sends a machine tripping signal to the intelligent on-site protection and control device of a step-up transformer with a larger output; if a second round of machine tripping signals are received subsequently, sends a machine tripping signal to the intelligent on-site protection and control devices of all remaining step-up transformers.

[0025] The beneficial effects of the present invention are as follows: the present invention adopts an intelligent on-site protection and measurement and control device with three-in-one intelligent terminals, merging units and protection and measurement and control functions, and integrates redundant backup protection and load control functions into the station protection and load control device. Compared with general intelligent substations, the number of intelligent terminals, merging units and backup protection devices is greatly reduced. At the same time, the number of cables is greatly reduced, and the construction difficulty is reduced, thereby reducing the volume of the offshore booster platform and saving the investment in the offshore wind power booster station.

[0026] The present invention combines the characteristics of offshore wind power and adopts load control methods such as output reduction control when the current carrying capacity exceeds the limit and multi-round machine cutting control after an accident. It can accurately control each group of wind turbine collection lines, and ensure that the collection line is not cut off more than once while eliminating overload, thereby avoiding excessive cutting of wind turbines to the greatest extent, improving the accuracy of offshore wind power load control, reducing wind farm power loss, and better ensuring the power generation efficiency of wind farms. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural schematic diagram of an embodiment.

[0028] Figure 2 It is a load control flow chart in the embodiment. DETAILED DESCRIPTION

[0029] This embodiment is an offshore wind power booster station load control system based on hierarchical protection. The system is implemented based on a hierarchical protection control system and adopts a hierarchical automatic control configuration technology. It is a control system implemented in terms of functional configuration and spatial configuration.

[0030] The spatial configuration of this embodiment is divided into local layer, station area layer and wide area layer, wherein the local layer includes local equipment such as intelligent local protection and control devices, intelligent terminals, and merging units of offshore booster stations; the station area layer includes station area protection and load control devices, monitoring background, communication management machine, station area layer switches, etc.; the wide area layer includes line load overload monitoring devices, monitoring background, dispatching workstations, etc. of onshore system stations. The local layer equipment is configured with each bay as a unit, which can realize the protection, measurement and control functions of the primary equipment in the bay, and complete the switch logic interlocking in the bay.

[0031] In this example, the local layer and the station layer equipment exchange digital sampling, switch quantities and other IEC61850 communication data through the station layer network to realize the exchange and sharing of data and information within the station area; the station layer and the wide area layer equipment exchange load control signals through the wide area communication network to realize the transmission of load control commands between the onshore system station and the offshore booster station.

[0032] In this embodiment, the functional configuration includes load data collection, load control strategy decision-making, and load control strategy execution, wherein the load data collection function and the load strategy execution function are realized by the intelligent on-site protection and measurement and control device of the control system, replacing the conventional safety and stability control slave machine; the load control strategy decision function is realized by the station protection and load control device of the control system, replacing the conventional safety and stability control host machine.

[0033] In this example, the intelligent local protection and control device includes multiple wind turbine incoming line protection and control devices, which are used to realize the load strategy execution function. This type of device is installed locally in the 35kV switch cabinet. The sampling value (SV) and signal quantity (GOOSE) information are sent by the 35kV intelligent local protection and control device of each interval to the corresponding SV network and GOOSE network at the station layer.

[0034] The station area protection and load control device in this embodiment integrates the station area protection function and load control function of the original intelligent station, and uses the sampled value (SV) and signal quantity (GOOSE) data collected by the device to distinguish the fault and state in the station without the help of external input contacts. Combined with the control signal of the onshore system substation line load overload monitoring device and the control strategy after the fault judgment of this machine, it realizes the automatic control functions such as the output reduction control of the current carrying capacity exceeding the limit and the multi-wheel cutting control after the accident within a limited time, thereby improving the safety and stability of the power system load. The highly integrated station area protection and load control device can adopt a dual-machine redundant configuration to increase reliability.

[0035] In this embodiment, the load control function of the station area protection and load control device is realized by the load control module. The load control module consists of four units: a detection unit, a judgment unit, a decision unit, and an execution unit. The detection unit is used to measure and store electrical quantities and switch quantities, and to judge the changes in electrical quantities and switch quantities. The judgment unit is used to start fault discrimination, perform fault judgment and identify the operation mode. The decision unit is used to select the control strategy and determine the control quantity. The execution unit is used to send the control object signal.

[0036] In this example, the line load overload monitoring device of the onshore system station is used to monitor the line overload state. When a load overload is detected, the device sends multiple rounds of load control commands to the station area protection and load control device of the offshore booster station.

[0037] The control method of the offshore wind power booster station load control system based on hierarchical protection in this embodiment specifically includes:

[0038] (1) The station protection and load control device generates a control strategy table. Through online analysis and calculation, according to the wind turbine output and cutting capacity of the intelligent booster station, the cutting queue and cutting object corresponding to the fault type and section power under different operating modes are obtained;

[0039] (2) The intelligent local protection measurement and control device obtains the sampling value (SV) and signal quantity (GOOSE) data of the wind turbine incoming line bay unit in real time, and uploads it to the station protection and load control device through the station control layer network;

[0040] (3) The line overload monitoring device of the onshore system station determines the line overload status and line fault status. The device detects the line overload or fault based on the line abnormality judgment criteria. The device sends a power reduction or machine disconnection signal to the station protection and load control device of the offshore booster station through the wide area communication network.

[0041] (4) The detection unit of the station protection and load control device detects the power reduction alarm signal issued by the onshore system substation. After receiving the power reduction alarm signal, the detection unit obtains the real-time power of each wind turbine collection line; the judgment unit starts the fault judgment and identification method, and calculates the power reduction; the decision unit determines the control quantity, queries the control strategy table, and selects the wind turbine collection line unit for power reduction; the execution unit sends a machine cutting signal to the corresponding 35kV wind turbine incoming line cabinet on-site intelligent protection and measurement and control device.

[0042] (5) The detection unit of the station area protection and load control device detects the power-off signal sent by the onshore system substation. After receiving the first round of power-off signal, the execution unit sends a power-off signal to the intelligent terminal of a step-up transformer with a larger output; if the second round of power-off signal is received subsequently, the execution unit sends a power-off signal to the intelligent terminals of all remaining step-up transformers.

[0043] In this embodiment, the line load overload criterion of the land system station is as follows:

[0044] When the current or power satisfies I ≥ I qd Or P ≥ P qd After that, the time satisfies t≥T qd When the overload start signal is issued, the overload start signal is issued; after the overload start signal is issued, when the current or power satisfies I≥I qj1 Or P ≥ P qj1 , time satisfies t≥T qj1 When the overload start signal is issued, when the current or power meets I≥I qj2 Or P ≥ P qj2 , time satisfies t≥T qj2 When the overload condition occurs, a second round of overload cutting command is issued.

[0045] In the above criteria, I is the line current collected by the line overload monitoring device, P is the line power calculated by the line overload monitoring device, and I qd is the overload starting current setting, P qd is the overload starting power setting, Tqd is the overload start time setting, I qj1 is the first round of cutting current setting, P qj1 is the power setting value of the first round of cutting, T qj1 is the first round of cutting time setting, I qj2 is the current setting value of the second round of cutting machine, P qj2 is the power setting value of the second round of cutting machine, T qj2 Set the time value for the second round of cutting.

[0046] In this embodiment, the method for determining the reduced output power control amount is as follows:

[0047] The detection unit of the station protection and load control device obtains the output reduction alarm signal of the onshore system substation and the total amount of load that needs to be removed P q , calculate the real-time power P of all 35kV wind turbine incoming line units i The decision-making unit compares the total load removal P according to the real-time power of all wind turbines. q Combined with the control strategy table, the load shedding sensitivity is sorted to form a real-time power and fan sensitivity association list. Each fan inlet unit is marked as P i j , j is the cut-off sequence number of each fan inlet unit, satisfying ΣP=P 1 +P 2 +…+P n The total load planned to be cut and the total load actually required to be cut P q To ensure that the collector line is cut off no more than once, the decision unit outputs the cutting machine number 1…n.

[0048] The load control system of this embodiment is based on a hierarchical structure, which can realize the comprehensive application of offshore booster station data information and can better ensure the load operation of the intelligent offshore booster station through the coordination of functions and space. The load control system solution is implemented on the basis of the station domain layer and the local layer of the intelligent station. At the local layer, a three-in-one intelligent protection and control device integrating intelligent terminals, merging units and protection and measurement and control functions is used to realize the digitization of the sampling values ​​and signal quantities of each interval unit required for the load control function; the station domain layer is equipped with a station domain protection and control device with fast backup protection, redundant backup protection and load control functions, which greatly reduces the number of intelligent secondary equipment in the station, thereby achieving the purpose of reducing the investment in secondary equipment; the load control module in the station domain protection and load control device can use the sampling value (SV) and signal quantity (GOOSE) data collected by this device to distinguish the fault and status in the station without the help of external input contacts, and combine the control signal of the onshore system substation line load overload monitoring device and the control strategy after the local fault is distinguished, so as to realize the automatic control functions such as over-limit reduction control of current carrying capacity and multi-wheel cutting control after the accident within a limited time, thereby achieving the purpose of improving the stability of the power system.

Claims

1. A load control system for an offshore wind power booster station based on hierarchical protection, characterized in that: The spatial configuration of the system is a local layer, a station area layer and a wide area layer, wherein the local layer is connected to the station area layer by communication, and the station area layer is connected to the wide area layer by communication; The local layer has an intelligent local protection measurement and control device, the station area layer has a station area protection and load control device, and the wide area layer has a line load overload monitoring device, wherein: The line load overload monitoring device is used to monitor the line overload state, and when a load overload or fault is detected, a power reduction or machine disconnection signal is sent to the station protection and load control device; The intelligent local protection and measurement and control device is used to obtain the real-time power of each wind turbine collector line in real time and upload it to the station protection and load control device; The station area protection and load control device is used to select the wind turbine collector line unit with reduced output according to the reduced output signal, the real-time power of each wind turbine collector line and the control strategy table, and send a machine cutting signal to the corresponding intelligent local protection measurement and control device; The station area protection and load control device is further used to send a machine cutting signal to the intelligent local protection measurement and control device corresponding to the step-up transformer with larger output according to the first round of machine cutting signals, and send a machine cutting signal to the intelligent local protection measurement and control devices corresponding to the remaining step-up transformers according to the second round of machine cutting signals; The line load overload judgment method of the line load overload monitoring device comprises: When the current or power satisfies I ≥ I qd Or P ≥ P qd After that, the time satisfies t≥T qd When the overload start signal is issued; After the overload start signal is issued, when the current or power satisfies I≥I qj1 Or P ≥ P qj1 , time satisfies t≥T qj1 When the first round of overload cutting command is issued; After the overload start signal is issued, when the current or power satisfies I≥I qj2 Or P ≥ P qj2 , time satisfies t≥T qj2 When the overload is reached, the second round of overload cutting command is issued; Where I is the line current collected by the line overload monitoring device, P is the line power calculated by the line overload monitoring device, and I qd is the overload starting current setting, P qd is the overload starting power setting value, Tqd is the overload starting time setting value, I qj1 is the first round of cutting current setting, P qj1 is the power setting value of the first round of cutting, T qj1 is the first round of cutting time setting, I qj2 is the current setting value of the second round of cutting machine, P qj2 is the power setting value of the second round of cutting machine, T qj2 Set the time value for the second round of cutting.

2. The offshore wind power booster station load control system based on hierarchical protection according to claim 1 is characterized in that: The method of selecting a wind turbine power collection line unit for power reduction according to the power reduction signal, the real-time power of each wind turbine power collection line and the control strategy table includes: According to the real-time power P of all fans i , the total amount of load removed P q , combined with the load sensitivity ranking in the control strategy table, determine the fan incoming line units that need to be cut off and the order of cutting off.

3. A control method for an offshore wind power booster station load control system based on hierarchical protection as claimed in any one of claims 1 to 2, characterized in that: include: The station protection and load control device generates a control strategy table. Through online analysis and calculation, according to the wind turbine output and cutting capacity of the intelligent booster station, the cutting queue and cutting object corresponding to the fault type and section power under different operating modes are obtained; The intelligent local protection measurement and control device obtains the sampling value and signal quantity data of the fan incoming line interval unit in real time, and uploads it to the station protection and load control device; The line load overload monitoring device of the onshore system station determines the line load overload status and line fault status, detects the line load overload or fault according to the line abnormality judgment criteria, and sends a power reduction or machine cutting signal to the station area protection and load control device of the offshore booster station; The station protection and load control device detects the reduced output alarm signal issued by the line load overload monitoring device, determines that after receiving the reduced output alarm signal, it obtains the real-time power of each wind turbine collector line, starts the fault judgment and identification method, calculates the reduced output power, queries the control strategy table, selects the reduced output wind turbine collector line unit, and sends a machine cutting signal to the corresponding intelligent local protection measurement and control device; The station area protection and load control device detects the machine-cutting signal sent by the line load overload monitoring device, and after determining that the first round of machine-cutting signals are received, sends a machine-cutting signal to the intelligent local protection and control device of a step-up transformer with a larger output; if a second round of machine-cutting signals are received subsequently, sends a machine-cutting signal to the intelligent local protection and control devices of all remaining step-up transformers; The line load overload judgment method of the line load overload monitoring device comprises: When the current or power satisfies I ≥ I qd Or P ≥ P qd After that, the time satisfies t≥T qd When the overload start signal is issued; After the overload start signal is issued, when the current or power satisfies I≥I qj1 Or P ≥ P qj1 , time satisfies t≥T qj1 When the first round of overload cutting command is issued; After the overload start signal is issued, when the current or power satisfies I≥I qj2 Or P ≥ P qj2 , time satisfies t≥T qj2 When the overload is reached, the second round of overload cutting command is issued; Where I is the line current collected by the line overload monitoring device, P is the line power calculated by the line overload monitoring device, and I qd is the overload starting current setting, P qd is the overload starting power setting value, Tqd is the overload starting time setting value, I qj1 is the first round of cutting current setting, P qj1 is the power setting value of the first round of cutting, T qj1 is the first round of cutting time setting, I qj2 is the current setting value of the second round of cutting machine, P qj2 is the power setting value of the second round of cutting machine, T qj2 Set the time value for the second round of cutting.

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