A frequency fast response guide vane control method for full power direct drive variable speed hydropower unit

Abstract

The invention discloses a method for controlling a frequency fast-response guide vane of a full-power direct-drive variable-speed hydropower unit, which comprises: step 1, during the normal operation of the variable-speed constant-frequency hydropower unit connected to the grid, the unit speed governor collects the current analog values ​​in real time through a collection system; step 2, determining the current guide vane opening adjustment target value of the speed governor according to the system frequency value; the method solves the problem that the existing hydropower unit needs fast active power support when the system frequency changes, while the unit does not have a large power reverse regulation characteristic, and realizes the problem of fast and stable response of the unit to the grid frequency.

Description

Technical Field

[0001] The invention belongs to the technical field of water turbine regulating methods, and in particular relates to a frequency rapid response guide vane control method for a full-power direct-drive variable-speed water turbine unit. Technical Background

[0002] Hydropower units are widely used in power generation systems due to their flexible regulation and fast response speed. However, at present, due to the problem of water flow inertia, hydropower units are prone to reverse regulation during rapid frequency regulation, which brings short-term reverse power to the power system and is more detrimental to the stable operation of the system. With the development of frequency conversion technology, variable-speed turbine units have also been widely used due to their strong adaptability to working conditions. The full-power variable-speed turbine unit is connected to the power system by inverting and rectifying the three-phase power supply, and the speed change of the turbine is achieved on the basis of ensuring the output frequency of 50Hz, thereby realizing the characteristics of strong adaptability to the working conditions of the unit. There is no direct coupling relationship between the speed of the new full-power variable-speed hydropower unit and the grid frequency. Therefore, the active output can be quickly adjusted by controlling the converter method, and the system frequency fluctuation can be suppressed by releasing a part of the mechanical rotation energy. Then, the frequency regulation function of the unit is realized in conjunction with the corresponding guide vane control law of the speed regulator. At the same time, the power reverse regulation problem of the unit caused by the water flow inertia problem in the rapid frequency regulation process is effectively suppressed. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a frequency rapid response guide vane control method for a full-power direct-drive variable-speed hydropower unit, so as to solve the problem that the existing hydropower units need rapid active power support when the system frequency changes, while not having a large power reverse regulation characteristic of the unit, and realize the unit's rapid and stable response to the grid frequency.

[0004] Technical solution of the present invention:

[0005] A frequency fast response guide vane control method for a full-power direct-drive variable-speed hydropower unit, comprising:

[0006] Step 1: During the normal operation of the variable speed constant frequency hydropower unit connected to the grid, the unit speed governor collects the current analog values ​​in real time through the acquisition system;

[0007] Step 2: Determine the current guide vane opening adjustment target value of the speed governor according to the system frequency value.

[0008] The analog values ​​in step 1 include: the current upstream water level h(i), the current grid frequency f(i), the current active power of the unit p(i), the current calculated given guide vane opening value y of the speed regulator g and the upstream water level h of the unit at rated operating condition g .

[0009] The determination of the current regulating target value of the guide vane opening of the governor according to the system frequency value described in Step 2 includes: judging the system frequency value in real time. When 49.5Hz < f(i) < 50.5Hz,

[0010] the current regulating target value y(i) of the guide vane opening of the governor = y g ; the guide vane opening of the governor follows the given value, and y g is the current calculated given guide vane opening value of the governor.

[0011] The determination of the current regulating target value of the guide vane opening of the governor according to the system frequency value described in Step 2 includes:

[0012] judging the system frequency value in real time. When f(i) < 49.5Hz, the unit enters the frequency modulation mode, and the unit power converter increases the power output to the system. The output power p(i) = p 0 + p g *(50 - f(i)) / 50 * e p , where: p 0 is the initial active power value before entering the frequency modulation mode, e p is the power regulation differential coefficient, and p g is the rated power of the unit;

[0013] At the same time, the unit governor performs frequency modulation actions. The current regulating target value y(i) of the guide vane opening of the governor = y 0 + 100*(50 - f(i)) / 50 * b p

[0014] where y 0 is the initial guide vane value before entering the frequency modulation mode, and b p is the permanent speed droop coefficient.

[0015] To prevent the unit from having reverse regulation phenomena, the calculation formula for the guide vane action law is:

[0016] y(k) = y(k - 1)+(z k / z q ){K p [e(k)-e(k - 1)]+K i e(k)△t}

[0017] where: k is the sampling number, △t is the sampling period, K p is the proportional gain under the frequency regulation of the governor, K i is the integral gain of the loop under the frequency regulation of the governor, e(k) is the error between the guide vane regulation value and the regulation target during the regulation process, z is the action slow coefficient, and q is the action slow time coefficient;

[0018] e(k) = y(i)-y(k);

[0019] When k=q, it enters the late stage of action, and the action rules are as follows:

[0020] y(k)=y(k-1)+{K p [e(k)-e(k-1)]+K i e(k)△t}

[0021] Where: k is the number of sampling times, △t is the sampling period, K p K is the proportional gain of the speed regulator under frequency regulation; i is the loop integral gain under the frequency regulation of the speed regulator; e(k) is the error between the guide vane regulation value and the regulation target during the regulation process;

[0022] e(k)=y(i)-y(k).

[0023] Determining the current guide vane opening adjustment target value of the speed governor according to the system frequency value in step 2 includes:

[0024] Real-time judgment of system frequency value. When f(i)>50.5Hz, the unit enters frequency modulation mode; the unit power converter reduces power output to the system, and the output power p(i)=p 0 -p g *(f(i)-50) / 50*e p ;

[0025] Where: p 0 is the initial value of active power before entering frequency modulation mode, e p is the power regulation coefficient p g is the rated power of the unit;

[0026] At the same time, the unit speed governor performs frequency regulation, and the current guide vane opening adjustment target value of the speed governor is y(i) = f 0 -100*(f(i)-50) / 50*b p ;

[0027] Where f 0 is the initial value of the guide vane before entering the frequency modulation mode, b p is the permanent slip coefficient.

[0028] In order to prevent the unit from reverse adjustment, the guide vane action law is

[0029] y(k)=y(k-1)-(z k / z q ){K p [e(k)-e(k-1)]+K i e(k)△t}

[0030] Where: k is the number of sampling times, △t is the sampling period, K pis the proportional gain under governor frequency regulation, K i is the integral gain of the loop under governor frequency regulation, e(k) is the error between the guide vane adjustment value and the adjustment target during the adjustment process, z is the slow action coefficient, and q is the slow action time coefficient;

[0031] e(k) = y(i) - y(k);

[0032] When k = q, it enters the late stage of action, and the action law is as follows:

[0033] y(k) = y(k - 1) - {K p [e(k) - e(k - 1)] + K i e(k)△t}

[0034] In the formula: k is the sampling number, △t is the sampling period, K p is the proportional gain under governor frequency regulation; K i is the integral gain of the loop under governor frequency regulation; e(k) is the error between the guide vane adjustment value and the adjustment target during the adjustment process;

[0035] e(k) = y(i) - y(k).

[0036] Advantages of the present invention:

[0037] By changing the dynamic control method of the guide vane in the frequency modulation mode, the present invention effectively reduces the reverse regulation characteristic of the water turbine in the initial stage of the frequency modulation model. By releasing and absorbing the corresponding inertial energy of the rotating part of the hydroelectric generating unit, it is not necessary for the guide vane to act quickly in the initial stage of frequency modulation, and the power regulation is realized through the guide vane control of the governor in the later stage of frequency modulation, solving the problem that the water turbine governor in the prior art has reverse regulation in the fast frequency modulation mode and affecting the stability of the power grid. Specific implementation manner

[0038] A guide vane control method for rapid frequency response of a full-power direct-drive variable-speed hydroelectric generating unit, which includes: during the normal operation of the grid-connected variable-speed constant-frequency hydroelectric generating unit, the unit governor collects the current analog quantity values in real time through the acquisition system. When operating under a certain load condition, y(i) is the current guide vane opening adjustment target value of the governor (unit: %), h(i) is the current upstream water level value (unit: m), f(i) is the current grid frequency value, p(i) is the current active power of the unit (unit: MW), y g is the current calculated given guide vane opening value of the governor (unit: %), and the upstream water level h under the rated condition of the unit g .

[0039] Judge the system frequency value in real time. When 49.5Hz < f(i) < 50.5Hz,

[0040] The current guide vane opening value of the speed controller is y(i) = y g ;The guide vane opening of the speed regulator follows the given value.

[0041] y g The current calculated guide vane opening value for the speed governor (unit: %)

[0042] Real-time judgment of system frequency value, when f(i)<49.5Hz, the unit enters frequency modulation mode. The unit power converter increases power output to the system, and its output power p(i)=p 0 +p g *(50-f(i)) / 50*e p , the unit speed decreases accordingly.

[0043] Where p 0 is the initial value of active power before entering frequency modulation mode, e p is the power regulation coefficient, p g is the rated power of the unit.

[0044] At the same time, the unit speed governor performs frequency regulation, and its action target calculation value is y(i) = y 0 +100*(50-f(i)) / 50*b p .

[0045] Where y 0 is the initial value of the guide vane before entering the frequency modulation mode, b p is the permanent slip coefficient.

[0046] In the early stage of operation, the guide vane movement speed is relatively fast. In order to prevent the unit from experiencing reverse adjustment, the guide vane calculation formula is:

[0047] y(k)=y(k-1)+(z k / z q ){K p [e(k)-e(k-1)]+K i e(k)△t}

[0048] Where: k is the number of sampling times, △t is the sampling period, K p K is the proportional gain of the speed regulator under frequency regulation; i is the loop integral gain under the frequency regulation of the speed regulator; e(k) is the error between the guide vane regulation value and the regulation target during the regulation process; z is the slow action coefficient; q is the slow action time coefficient, the larger the coefficient, the longer the slow rise time.

[0049] e(k)=y(i)-y(k);

[0050] When k=q, it enters the late stage of action, and the guide vane action speed needs to be adjusted quickly. The action rules are as follows:

[0051] y(k)=y(k-1)+{K p [e(k)-e(k-1)]+K i e(k)△t}

[0052] Where: k is the number of sampling times, △t is the sampling period, K p K is the proportional gain of the speed regulator under frequency regulation; i is the loop integral gain under the frequency regulation of the speed regulator; e(k) is the error between the guide vane regulation value and the regulation target during the regulation process.

[0053] e(k)=y(i)-y(k);

[0054] Real-time judgment of system frequency value, when f(i)>50.5Hz, the unit enters frequency modulation mode. The unit power converter reduces power output to the system, and its output power p(i)=p 0 -p g *(f(i)-50) / 50*e p , the unit speed increases accordingly.

[0055] Where p 0 is the initial value of active power before entering frequency modulation mode, e p is the power regulation coefficient p g is the rated power of the unit.

[0056] At the same time, the unit speed governor performs frequency regulation, and its action target calculation value is y(i) = f 0 -100*(f(i)-50) / 50*b p .

[0057] Where f 0 is the initial value of the guide vane before entering the frequency modulation mode, b p is the permanent slip coefficient.

[0058] The guide vane movement speed is low in the early stage of action to prevent the unit from reverse adjustment.

[0059] y(k)=y(k-1)-(z k / z q ){K p [e(k)-e(k-1)]+K i e(k)△t}

[0060] Where: k is the number of sampling times, △t is the sampling period, K p K is the proportional gain of the speed regulator under frequency regulation; iis the loop integral gain under the frequency regulation of the speed regulator; e(k) is the error between the guide vane regulation value and the regulation target during the regulation process; z is the slow action coefficient; q is the slow action time coefficient, the larger the coefficient, the longer the slow rise time.

[0061] e(k)=y(i)-y(k);

[0062] When k=q, it enters the late stage of action, and the guide vane action speed needs to be adjusted quickly. The action rules are as follows:

[0063] y(k)=y(k-1)-{K p [e(k)-e(k-1)]+K i e(k)△t}

[0064] Where: k is the number of sampling times, △t is the sampling period, K p K is the proportional gain of the speed regulator under frequency regulation; i is the loop integral gain under the frequency regulation of the speed regulator; e(k) is the error between the guide vane regulation value and the regulation target during the regulation process.

[0065] e(k)=y(i)-y(k).

Claims

1. A method for controlling the guide vane of a full-power direct-drive variable-speed hydro-generating unit for rapid frequency response, which comprises: Step 1: During the normal operation of the grid-connected variable-speed constant-frequency hydro-generating unit, the unit governor collects the current analog quantity values in real time through the acquisition system; Step 2: Determine the current guide vane opening adjustment target value of the governor according to the system frequency value; The determination of the current guide vane opening adjustment target value of the governor according to the system frequency value in Step 2 includes: Judge the system frequency value in real time. When 49.5Hz < f(i) < 50.5Hz, The current guide vane opening adjustment target value of the speed governor y(i) = y g ,y g Calculate the given guide vane opening value for the current speed governor; Real-time judgment of system frequency value. When f(i)<49.5Hz, the unit enters frequency modulation mode, and the unit power converter increases power output to the system. Output power p(i)=p 0 +p g *(50-f(i)) / 50*e p , where: p 0 is the initial value of active power before entering frequency modulation mode, e p is the power regulation coefficient, p g is the rated power of the unit; At the same time, the unit speed governor performs frequency regulation, and the current guide vane opening adjustment target value of the speed governor y(i) = y 0 +100*(50-f(i)) / 50*b p Where y 0 is the initial value of the guide vane before entering the frequency modulation mode, b p is the permanent slip coefficient; Real-time judgment of system frequency value. When f(i)>50.5Hz, the unit enters frequency modulation mode; the unit power converter reduces power output to the system, and the output power p(i)=p 0 -p g *(f(i)-50) / 50*e p ; Where: p 0 is the initial value of active power before entering frequency modulation mode, e p is the power regulation coefficient p g is the rated power of the unit; At the same time, the unit speed governor performs frequency regulation, and the current guide vane opening adjustment target value of the speed governor is y(i) = f 0 -100*(f(i)-50) / 50*b p ; Where f 0 is the initial value of the guide vane before entering the frequency modulation mode, b p is the permanent slip coefficient.

2. A method for controlling the guide vane of a full-power direct-drive variable-speed hydro-generating unit for rapid frequency response according to Claim 1, characterized in that: The analog values ​​in step 1 include: the current upstream water level h(i), the current grid frequency f(i), the current active power of the unit p(i), the current calculated given guide vane opening value y of the speed regulator g and the upstream water level h of the unit at rated operating condition g .

3. A method for controlling the guide vane of a full-power direct-drive variable-speed hydro-generating unit for rapid frequency response according to Claim 1, characterized in that: To prevent the unit from having reverse regulation phenomenon, the calculation formula of the guide vane action law is: y(k)=y(k-1)+(z k / z q ){K p [e(k)-e(k-1)]+K i e(k)△t} Where: k is the number of sampling times, △t is the sampling period, K p is the proportional gain of the speed regulator under frequency regulation, K i is the loop integral gain under the governor frequency regulation, e(k) is the error between the guide vane regulation value and the regulation target during the regulation process, z is the action slowness coefficient, and q is the action slowness time coefficient; e(k) = y(i) - y(k); When k = q, it enters the later stage of the action, and the action law is as follows: y(k)=y(k-1)+{K p [e(k)-e(k-1)]+K i e(k)△t} Where: k is the number of sampling times, △t is the sampling period, K p K is the proportional gain of the speed regulator under frequency regulation; i is the loop integral gain under the frequency regulation of the speed regulator; e(k) is the error between the guide vane regulation value and the regulation target during the regulation process; e(k) = y(i) - y(k).

4. A method for controlling the guide vane of a full-power direct-drive variable-speed hydro-generating unit for rapid frequency response according to Claim 1, characterized in that: To prevent the unit from having reverse regulation phenomenon, the guide vane action law is y(k)=y(k-1)-(z k / z q ){K p [e(k)-e(k-1)]+K i e(k)△t} Where: k is the number of sampling times, △t is the sampling period, K p is the proportional gain of the speed regulator under frequency regulation, K i is the loop integral gain under the governor frequency regulation, e(k) is the error between the guide vane regulation value and the regulation target during the regulation process, z is the action slowness coefficient, and q is the action slowness time coefficient; e(k) = y(i) - y(k); When k = q, it enters the later stage of the action, and the action law is as follows: y(k)=y(k-1)-{K p [e(k)-e(k-1)]+K i e(k)△t} Where: k is the number of sampling times, △t is the sampling period, K p K is the proportional gain of the speed regulator under frequency regulation; i is the loop integral gain under the frequency regulation of the speed regulator; e(k) is the error between the guide vane regulation value and the regulation target during the regulation process; e(k) = y(i) - y(k).