Power fluctuation control system and method for new energy transmission via flexible direct transmission system

Abstract

This invention discloses a power fluctuation control system for a new energy power transmission system via flexible direct current (FDDC). A fluctuation sequence extraction module calculates the real-time power fluctuation sequence, a variance calculation module calculates the fluctuation variance based on the power fluctuation sequence, a control quantity calculation module calculates the control quantity based on the fluctuation variance, a frequency value calculation module calculates an additional frequency value and a new frequency setpoint based on the control quantity, and a frequency setpoint adjustment module sends the new frequency value to the FDDC control system to adjust the output of the new energy generating units. This invention can suppress the volatility of the new energy power transmission system via FDDC, improving the stability and security of the power grid.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of new energy control technology, in particular to a power fluctuation control system and method of new energy through flexible direct transmission system. BACKGROUND

[0002] The new energy base of million kilowatts becomes a new mode of developing new energy, but the fluctuation and randomness of new energy also bring great challenges to the dispatching operation of the power grid. Large-scale new energy station is usually at the end of the power grid, and the network structure is weak. In order to better accommodate new energy and fully realize the centralized transmission of large-scale new energy, flexible direct current transmission technology becomes one of the ideal choices for power transmission. When new energy is transmitted through flexible direct transmission, the voltage-frequency (V / F) control is adopted at the sending end of the flexible direct transmission. Under this control strategy, the active power of the island converter station completely depends on the actual active power of the new energy power supply of the island sending system, and the fluctuation of the new energy power supply will be completely transmitted to the receiving end of the power grid. And the frequency of the AC power grid of the island sending system remains 50Hz in theory when the power fluctuates, and the function of adjusting the output of the new energy unit through frequency change is not applicable. SUMMARY

[0003] The purpose of the present application is to provide a power fluctuation control system and method of new energy through flexible direct transmission system, which can improve the stability and safety of the power grid.

[0004] To achieve this purpose, the power fluctuation control system of new energy through flexible direct transmission system designed by the present application, the control system includes fluctuation sequence extraction module, variance calculation module, control quantity calculation module, frequency value calculation module, frequency fixed value adjustment module;

[0005] The fluctuation sequence extraction module is used to calculate the power fluctuation sequence of real-time power according to the real-time power of new energy collection bus obtained by real-time monitoring;

[0006] The variance calculation module is used to calculate the variance according to the power fluctuation sequence;

[0007] The control quantity calculation module is used to judge the control time of the flexible direct transmission system through the threshold value according to the fluctuation variance, and calculate the control quantity of the flexible direct transmission system;

[0008] The frequency value calculation module is used to calculate the additional frequency value according to the control quantity of the flexible direct transmission system, and then calculate the new frequency fixed value according to the additional frequency value;

[0009] The frequency fixed value adjustment module is used to issue the new frequency fixed value to the flexible control system through the additional frequency device, and adjust the output of the new energy unit.

[0010] The beneficial effects of the present application are:

[0011] The application calculates the fluctuation rate of new energy output by observing the new energy output in real time, sets a certain threshold, converts the fluctuation of the output into equivalent frequency fluctuation, and uses the new energy unit to respond to the frequency change, thereby inhibiting the fluctuation of the new energy through the flexible transmission system and improving the stability and safety of the power grid. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 It is a structural schematic diagram of the application;

[0013] Figure 2 It is a flowchart of the application. DETAILED DESCRIPTION

[0014] The application will be further described in detail below in combination with the drawings and specific embodiments:

[0015] As shown in a power fluctuation control system of a new energy through flexible transmission system, the control system comprises a fluctuation sequence extraction module, a variance calculation module, a control amount calculation module, a frequency value calculation module, and a frequency fixed value adjustment module. Figure 1 The fluctuation sequence extraction module is used to calculate the power fluctuation sequence of the real-time power according to the real-time power of the new energy collection bus obtained by real-time monitoring.

[0016] The variance calculation module is used to calculate the fluctuation variance according to the power fluctuation sequence.

[0017] The control amount calculation module is used to judge the flexible transmission system control time through the threshold value according to the fluctuation variance, and calculate the flexible transmission system control amount.

[0018] The frequency value calculation module is used to calculate the additional frequency value according to the flexible transmission system control amount, and calculate the new frequency fixed value according to the additional frequency value.

[0019] The frequency fixed value adjustment module is used to issue the new frequency fixed value to the flexible control system through the additional frequency device, and adjust the new energy unit output.

[0020] The flexible transmission system is used to control the frequency of the new energy unit. The additional frequency device is a hardware device, which is used to monitor the new energy power in real time, calculate the frequency value required to change the entire new energy flexible transmission system, and issue the instruction to the flexible control system. Only one such device is required for a system.

[0021] In the above technical solution, the specific method of the fluctuation sequence extraction module for calculating the power fluctuation sequence of the real-time power according to the real-time power of the new energy collection bus obtained by real-time monitoring is as follows:

[0022]

[0023] ​Adopt fixed time interval Inside, according to the absolute value of power fluctuation sequence, fixed time interval (Take 1 min), power fluctuation sequence is recorded as:

[0024] I=1, 2, 3...N

[0025] In the formula, The real-time power of the current time collection bus; The historical power of the previous time collection bus; The length of power fluctuation sequence.

[0026] In the above technical solution, the variance calculation module calculates the variance according to the power fluctuation sequence, and the specific method of obtaining the fluctuation variance is:

[0027] The power fluctuation sequence is calculated according to the sliding window method, and the length of the sliding window is set to , The value of is less than the length of the fluctuation sequence The fluctuation variance of new energy power can be recorded as :

[0028]

[0029]

[0030] In the formula, The average value of The fluctuation sequence.

[0031] In the above technical solution, the control amount calculation module is used to judge the time of the control of the flexible direct transmission system according to the fluctuation variance through the threshold value, and the specific method of calculating the control amount is:

[0032] The preset variance threshold is , It can be given according to experience, generally taking 5%, the fluctuation variance Less than the threshold value , there is no need to interfere with the output of new energy unit, the fluctuation variance Greater than the threshold value , the current time is set as the control time of the flexible direct transmission system, and the required control amount is recorded as :

[0033]

[0034] In the formula, The total output of new energy unit.

[0035] In the above technical solution, the frequency value calculation module is used to calculate an additional frequency value based on the control quantity, and then calculates a new frequency setting based on the additional frequency value. The specific method is as follows:

[0036] The additional frequency value is denoted as :

[0037]

[0038] In the formula, The conversion factor is an intermediate coefficient used to convert power values ​​into frequency values; its value depends on the installed capacity of new energy sources. Size. Generally, it can be taken , This is the control quantity for the flexible direct feed system.

[0039] Based on the calculated additional frequency value, the flexible DC transmission system is switched to the new frequency setpoint at the control moment of the aforementioned flexible DC transmission system, denoted as [missing value]. :

[0040]

[0041] In the formula, The rated frequency of the new energy unit is 50Hz, which is taken in this paper.

[0042] In the above technical solution, the frequency setpoint adjustment module sends the new frequency setpoint to the flexible DC control system through an additional frequency device. The specific method for adjusting the output of the new energy unit is as follows:

[0043] The new frequency setpoint is sent to the flexible DC control system via an additional frequency device. The flexible DC control system changes the frequency value, and each renewable energy unit adjusts its output according to the new frequency setpoint and the pre-set renewable energy unit power and frequency strategy. The change in the renewable energy unit output is recorded as follows: ;

[0044]

[0045] In the formula, For the change in output of the i-th new energy unit; Let be the frequency regulation coefficient of the i-th new energy unit.

[0046] like Figure 2 The power fluctuation control method of a new energy transmission system via flexible direct transmission, as shown, includes the following steps:

[0047] Step 1: Calculate the power fluctuation sequence of the real-time power based on the real-time power of the new energy collection bus obtained from real-time monitoring;

[0048] Step 2: variance calculation according to the power fluctuation sequence, and the fluctuation variance is obtained;

[0049] Step 3: the fluctuation variance is judged by a threshold to determine the control time of the HVDC transmission system, and the HVDC transmission system control amount is calculated;

[0050] Step 4: the additional frequency value is calculated according to the HVDC transmission system control amount, and the new frequency setting value is calculated according to the additional frequency value;

[0051] Step 5: the new frequency setting value is issued to the HVDC control system through the additional frequency device to adjust the output of the new energy unit.

[0052] The above technical method also includes a computer readable storage medium, the computer readable storage medium stores a computer program, and the computer program is executed by a processor to realize the steps of the method of the power fluctuation control method of the new energy through the HVDC transmission system.

[0053] The contents not described in detail in the specification belong to the prior art known to those skilled in the art.

Claims

1. A power fluctuation control system of a new energy flexible direct transmission system, characterized in that: The control system comprises a fluctuation sequence extraction module, a variance calculation module, a control quantity calculation module, a frequency value calculation module, and a frequency setting value adjustment module. The fluctuation sequence extraction module is configured to calculate a power fluctuation sequence of real-time power according to real-time power of the new energy collection bus obtained through real-time monitoring. The variance calculation module is configured to calculate variance according to the power fluctuation sequence. The control quantity calculation module is configured to determine a time for controlling the HVDC transmission system according to the variance and calculate a control quantity of the HVDC transmission system. The frequency value calculation module is configured to calculate an additional frequency value according to the control quantity of the HVDC transmission system and calculate a new frequency setting value according to the additional frequency value. The frequency setting value adjustment module is configured to send the new frequency setting value to the HVDC control system through an additional frequency device to adjust the output of the new energy unit. The control quantity calculation module is configured to determine a time for controlling the HVDC transmission system according to the variance and calculate a control quantity of the HVDC transmission system. The preset variance threshold is γ, and the fluctuation variance s 2 If s > γ, the current time is set as the HVDC transmission system control time, and the required control amount is denoted as ΔP: ΔP = (s 2 -γ) x P 总 In the formula, P 总 is the total output of new energy units; The frequency value calculation module is configured to calculate an additional frequency value according to the control quantity of the HVDC transmission system. The additional frequency value is denoted as Δf, and Δf = k × ΔP, where k is a power / frequency conversion coefficient, and ΔP is the control quantity of the HVDC transmission system. The frequency value calculation module is configured to calculate a new frequency setting value according to the additional frequency value. The frequency setting value adjustment module is configured to send the new frequency setting value to the HVDC control system through an additional frequency device to adjust the output of the new energy unit. The fluctuation sequence extraction module is configured to calculate a power fluctuation sequence of real-time power according to real-time power of the new energy collection bus obtained through real-time monitoring. The additional frequency value is added to the rated frequency value of the new energy unit as a new frequency setting value f set : f set = f N + Δf In the formula, f N is the rated frequency of the new energy unit; The power fluctuation sequence is denoted as ΔP, and ΔP = |P(t) - P(t-1)|, where P(t) is the real-time power at time t, and P(t-1) is the real-time power at time t-1. The new frequency value is issued to the flexible direct current control system through an additional frequency device, the flexible direct current control system changes the frequency value, each new energy unit adjusts the output according to the new frequency value and the set new energy unit power and frequency strategy, and the output change of the new energy unit is denoted as ΔP G ; ΔP Gi = k i × f set In the formula, ΔP Gi is the output change of the i th new energy unit; k i is the frequency modulation coefficient of the i th new energy unit.

2. The power fluctuation control system of the new energy through flexible sending out system according to claim 1, characterized in that: The variance calculation module is configured to calculate variance according to the power fluctuation sequence. It comprises the following steps: M i = |P i -P i-1 i = 1, 2, 3...N In the formula, P i is the real-time power of the collection bus at the current time; P i-1 is the historical power of the collection bus at the previous time; and N is the length of the power fluctuation sequence.

3. The power fluctuation control system of the new energy through flexible direct transmission system according to claim 2, characterized in that: Step 1: calculate a power fluctuation sequence of real-time power according to real-time power of the new energy collection bus obtained through real-time monitoring. The variance of the power fluctuation sequence is calculated in a sliding window manner, specifically, the length of the sliding window is set as K, the value of K is less than the length N of the fluctuation sequence, and the fluctuation variance of the new energy power can be denoted as s 2 : In the formula, M 平均 is the average value of the K fluctuation sequences.

4. A power fluctuation control method for a new energy flexible direct transmission system based on the system of claim 1, characterized in that, Step 2: calculate variance according to the power fluctuation sequence. Step 3: determine a time for controlling the HVDC transmission system according to the variance and calculate a control quantity of the HVDC transmission system. Step 4: calculate an additional frequency value according to the control quantity and calculate a new frequency setting value. Step 5: send the new frequency setting value to the HVDC control system through an additional frequency device to adjust the output of the new energy unit. The computer program is executed by a processor to realize the steps of the method of claim 4. ​ 5. A computer readable storage medium storing a computer program, characterized in that: ​

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