CN115562013A - Evaluation method and control method of maximum power step of full power pumped storage unit - Google Patents

Abstract

The invention discloses a method for evaluating the maximum power step of a full-power pumped-storage unit, a control method, and obtaining a data set of working conditions; constructing a load model, and calculating the frequency response curve of the reduced-order active frequency response model under power step excitation; according to The frequency response curve calculates the maximum power step amount corresponding to each group of data in the working condition data set under the safety constraint condition, and obtains the maximum power step amount data set; obtains the working condition data and the power adjustment command; converts the maximum power step Match the jump data set to obtain the maximum power step data corresponding to the working condition data; based on the power adjustment command, judge whether the step capability of the maximum power step data is within the power regulation capability range, and if so, then The full-power pumped-storage unit is directly processed in steps; the beneficial effect of the present invention is to realize the release of the rapid power step adjustment capability of the full-power pumped-storage unit, so that the full-power pumped-storage unit can fully exert its fast power under the premise of ensuring safety. support capacity.

Description

Evaluation method and control method of maximum power step of full power pumped storage unit

technical field

The invention relates to the technical field of operation control of a full-power variable-speed constant-frequency pumped-storage unit, and specifically relates to a method for evaluating and controlling a maximum power step of a full-power pumped-storage unit.

Background technique

The full-power pumped-storage unit has speed regulation, excitation and frequency converter control systems, and the dynamic stability and coordination of each control system ensure the stable operation of the unit. The converter controls the power and the speed governor controls the fast power control mode. However, in this control mode, the rapid adjustment of the power of the full-power pumped storage unit will cause the unit speed (or frequency) to deviate from the optimal operating condition. Frequent adjustment will affect the operating efficiency of the unit, increase the vibration of the unit, and shorten the life of the unit. Usually, the control of the full-power pumped-storage unit is realized by strictly limiting the rapid power step of the full-power pumped-storage unit. However, this method , will result in the unit not being able to give full play to its rapid power support capability.

In view of this, this application is proposed.

Contents of the invention

The technical problem to be solved by the present invention is that the existing technology adopts the method of limiting the rapid power step to adjust the full-power pumped storage, which will cause the full-power pumped-storage unit to be unable to fully exert the supporting capacity of the fast power, and the purpose is to provide full-power pumped storage. The evaluation method and control method of the maximum power step of the storage unit can realize the support ability of the full-power pumped storage unit to fully exert the rapid power.

The present invention realizes through following technical scheme:

A method for evaluating the maximum power step of a full-power pumped storage unit, the method steps include:

Obtaining a working condition data set, the working condition data set is a unit power data set and a head data set of a full-power pumped storage unit during operation;

Construct a reduced-order active frequency response model, and calculate the frequency response curve of the reduced-order active frequency response model under power step excitation. The equivalent model under the influence of the device;

According to the frequency response curve, calculate the maximum power step amount corresponding to each set of data in the working condition data set under the safety constraint condition, and obtain the maximum power step amount data set.

Preferably, the specific calculation method of the frequency response curve includes:

A reduced-order active frequency response model is constructed, a small-signal model is constructed according to the reduced-order active frequency response model, and a frequency response curve of the small-signal model is extracted under load step excitation.

Preferably, the calculation method of the maximum power step includes:

Calculate a power step corresponding to each set of data in the working condition data set according to the frequency response curve and the working condition data set;

It is judged whether the corresponding frequency in the frequency response curve satisfies the safety constraint condition, and if so, the maximum power step amount is obtained.

Preferably, the security constraints specifically include:

During the unit power step process, the highest frequency f _max is greater than the frequency limit f _maxall corresponding to the overspeed protection, but the duration t _over is less than the action delay t _overdelay of the overspeed protection;

During the unit power step process, the minimum frequency f _min is less than the frequency limit f _minall corresponding to the underfrequency protection, but the duration t _low is less than the action delay t _lowdelay of the underfrequency protection;

During the unit power step process, the absolute value of the deviation |f _err | between the actual frequency f _real and the optimal frequency f _opt of the unit is greater than the allowable frequency absolute value |f _errall |, but the duration t _err is less than the maximum tolerance time t _errdelay .

Preferably, the reduced-order active frequency response model includes a governor, a water turbine, and a generator, the output of the governor is connected to the input of the water turbine, and the output of the water turbine is connected to the generator. The input end is connected, the output end of the generator outputs the actual power of the full-power pumped storage unit, and the actual power and the reference frequency of the full-power pumped storage unit are input to the governor, and the generator adopts a second-order model , the load model adopts a constant power load model and is connected in parallel at the generator end.

Preferably, the hydraulic turbine adopts an equivalent model that can consider the influence of initial operating head and load, and the specific expression is:

s is the Laplace operator; ΔPm is the mechanical power deviation of the turbine output; Δy is the guide vane opening deviation; T _wN is the water hammer time constant at the rated operating point; G _ht (s) is the transfer function of the turbine . P _m0 is the initial steady-state value of the output mechanical power of the turbine, and _h0 is the initial operating water head of the turbine.

Preferably, the specific expression of the small signal model is:

X is the state variable of the small signal model, Y is the output variable of the small signal model, U is the input variable of the small signal model; A is the state matrix of the small signal model, B is the input matrix of the small signal model, and C is the small signal model The output matrix of D is the transmission matrix of the small signal model.

Preferably, the specific expression of the maximum power step is:

t is the time, t _s is the adjustment time required for the frequency deviation of the unit to be less than the maximum allowable frequency deviation after the power step, and △P is the power step amount.

The present invention also provides a method for controlling the maximum power step of the full-power pumped storage unit, and the method steps include:

Obtain real-time operating condition data and power adjustment instructions of full-power pumped storage units;

Matching the working condition data with the maximum power step data set calculated by the evaluation method described above to obtain the maximum power step data corresponding to the working condition data;

Based on the power adjustment command, it is judged whether the step capability of the maximum power step data is within the power regulation capability range, if so, the full power pumped storage unit is directly step processed, otherwise, the power is added in stages.

Traditionally, when the power of the full-power pumped-storage unit is quickly adjusted, the control of the full-power pumped-storage unit is usually achieved by strictly limiting the rapid power step of the full-power pumped-storage unit, but this method , will cause the unit to fail to give full play to the fast power support capability; the invention provides a method for controlling the maximum power step of the full-power pumped storage unit, by matching the real-time working condition data with the calculated maximum power step, directly according to The matched data adjusts the full-power pumped-storage unit in real time, realizing the rapid power step adjustment capability of the full-power pumped-storage unit, so that the full-power pumped-storage unit can fully exert the supporting capacity of fast power.

Preferably, the specific method steps of adding power in stages include: performing the first adjustment with the maximum power step capability, and after delaying time t, adding power linearly with slope k until reaching the target power.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

The method for evaluating and controlling the maximum power step of a full-power pumped storage unit provided by the embodiment of the present invention matches the real-time working condition data with the calculated maximum power step, and directly adjusts the full-power pumping power according to the matched data. The real-time adjustment of the storage unit releases the rapid power step adjustment capability of the full-power pumped-storage unit, allowing the full-power pumped-storage unit to give full play to the support capacity of fast power under the premise of ensuring safety.

Description of drawings

In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention. Therefore, it should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained according to these drawings without creative work.

Figure 1 is a schematic diagram of the evaluation method;

Fig. 2 is the control method flowchart;

Figure 3 is the frequency response curve of the unit;

Figure 4 shows the active power of the unit under the condition of operating water head 130m and load 4MW;

Figure 5 shows the frequency of the unit under the condition of operating water head 130m and load 4MW;

Fig. 6 is a schematic diagram of a reduced-order active frequency response model.

detailed description

In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the examples and accompanying drawings. As a limitation of the present invention.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that these specific details need not be employed to practice the present invention. In other instances, well-known structures, circuits, materials or methods have not been described in detail in order not to obscure the present invention.

Throughout this specification, reference to "one embodiment," "an embodiment," "an example," or "example" means that a particular feature, structure, or characteristic described in connection with the embodiment or example is included in the present invention. In at least one embodiment. Thus, appearances of the phrases "one embodiment," "an embodiment," "an example," or "example" in various places throughout this specification are not necessarily all referring to the same embodiment or example. Furthermore, particular features, structures or characteristics may be combined in any suitable combination and/or subcombination in one or more embodiments or examples. Furthermore, those of ordinary skill in the art will appreciate that the drawings provided herein are for illustrative purposes and are not necessarily drawn to scale. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

In the description of the present invention, the terms "front", "rear", "left", "right", "upper", "lower", "vertical", "horizontal", "higher", "lower", "inner ", "outside" and other indicated orientations or positional relationships are based on the orientations or positional relationships shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific Orientation, construction and operation in a particular orientation, therefore, should not be construed as limiting the scope of the invention.

Embodiment one

This embodiment discloses a method for evaluating the maximum power step of a full-power pumped-storage unit. This embodiment is an evaluation of the power step adjustment capability of a full-power pumped-storage unit before the full-power pumped-storage unit is regulated. That is, under the influence of the excitation system and the converter of the unit, the maximum power step corresponding to the working condition data is calculated by constructing an equivalent model, and then when the full-power pumped storage unit is running in real time, it is carried out through the implementation data. Match the corresponding maximum power step to adjust. The core idea of this method is to ignore the influence of the excitation system and the converter of the unit, and the full-power variable speed pumped storage unit is equivalent to a single unit with a constant power load model that retains the speed control system. Compared with the complete unit model, the model reduces the model order, so the present invention is called a reduced-order active frequency response model; based on the model, the unit frequency response under power step excitation is solved. Based on the frequency response curve, in order to meet the requirements of not triggering frequency protection and the actual frequency deviation from the optimal frequency as constraints, the maximum power step allowed under each working condition is obtained.

As shown in Figure 1, the method steps include:

S1: Acquire the working condition data set, which is the unit power data set and water head data set of the full-power pumped storage unit during operation; in step S1, the obtained working condition data set is the full-power pumped-storage unit The power data and water head data of the unit in the real-time operation state of the unit, and in the working condition data set, it includes the combination of different data sets under various conditions. Maximum power step size under influence.

S2: Construct a load model, and calculate the frequency response curve of the reduced-order active frequency response model under power step excitation, and the negative reduced-order active frequency response model is ignoring the excitation system of the full-power pumped storage unit and the converter Equivalent model under influence;

The concrete calculating method of described frequency response curve comprises:

A reduced-order active frequency response model is constructed, a small-signal model is constructed according to the reduced-order active frequency response model, and a frequency response curve of the small-signal model is extracted under load step excitation.

In this embodiment, the constructed load model is shown in Figure 6, in which _ω0 is the reference frequency of the unit, ω is the actual frequency of the unit, and P _e is the equivalent load of the unit. Compared with the complete model of the full-power unit, this model does not consider the influence of the excitation system, but considers the detailed model of the governor, and the generator adopts a second-order model.

The reduced-order active frequency response model includes a governor, a water turbine, a generator, and a load. The output of the governor is connected to the input of the water turbine, and the output of the water turbine is connected to the input of the generator. The output terminal of the generator outputs the actual power of the full-power pumped-storage unit, and the actual power and the reference frequency of the full-power pumped-storage unit are input to the governor, and the generator adopts a second-order model, The load model adopts a constant power load model, which is connected in parallel at the generator end.

The hydraulic turbine adopts an equivalent model that can consider the influence of initial operating head and load, and the specific expression is:

s is the Laplace operator; ΔPm is the mechanical power deviation of the turbine output; Δy is the guide vane opening deviation; T _wN is the water hammer time constant at the rated operating point; G _ht (s) is the transfer function of the turbine . P _m0 is the initial steady-state value of the output mechanical power of the turbine, and _h0 is the initial operating water head of the turbine.

According to the reduced-order active frequency response model described in Fig. 6, set up its small-signal model, the concrete expression of described small-signal model is:

X is the state variable of the small signal model, Y is the output variable of the small signal model, U is the input variable of the small signal model; A is the state matrix of the small signal model, B is the input matrix of the small signal model, and C is the small signal model The output matrix of D is the transmission matrix of the small signal model.

S3: According to the frequency response curve, calculate the maximum power step amount corresponding to each set of data in the working condition data set under the safety constraint condition, and obtain the maximum power step amount data set.

The calculation method of the maximum power step comprises:

Calculate a power step corresponding to each set of data in the working condition data set according to the frequency response curve and the working condition data set;

It is judged whether the corresponding frequency in the frequency response curve satisfies the safety constraint condition, and if so, the maximum power step amount is obtained.

The specific expression of the security constraints is:

Specifically include:

During the unit power step process, the highest frequency f _max is greater than the frequency limit f _maxall corresponding to the overspeed protection, but the duration t _over is less than the action delay t _overdelay of the overspeed protection;

During the unit power step process, the minimum frequency f _min is less than the frequency limit f _minall corresponding to the underfrequency protection, but the duration t _low is less than the action delay t _lowdelay of the underfrequency protection;

During the unit power step process, the absolute value of the deviation |f _err | between the actual frequency f _real and the optimal frequency f _opt of the unit is greater than the allowable frequency absolute value |f _errall |, but the duration t _err is less than the maximum tolerance time t _errdelay .

The specific expression of the maximum power step is:

t is the time, t _s is the adjustment time required for the frequency deviation of the unit to be less than the maximum allowable frequency deviation after the power step, and △P is the power step amount.

Specific examples:

Taking a full-power pumped-storage unit with a power level of 5MW as an example, the response of the reduced-order active frequency small-signal model proposed in this patent is obtained. Under different working conditions, the frequency response under a certain power step signal excitation is shown in Figure 3.

The method for evaluating the maximum power step of the full-power pumped-storage unit disclosed in this embodiment is to calculate the corresponding frequency response curve by setting the equivalent load model of the full-power pumped-storage unit, and calculate the working condition data through the frequency response curve The maximum power step corresponding to the set can realize the calculation of the maximum power step corresponding to each set of data.

Embodiment two

This embodiment discloses a method for controlling the maximum power step of a full-power pumped storage unit, as shown in Figure 2, the method steps include:

Obtain real-time operating condition data and power adjustment instructions of full-power pumped storage units;

Matching the working condition data with the maximum power step data set calculated by an evaluation method in the embodiment to obtain the maximum power step data corresponding to the working condition data;

Based on the power adjustment command, it is judged whether the step capability of the maximum power step data is within the power regulation capability range, if so, the full power pumped storage unit is directly step processed, otherwise, the power is added in stages.

The specific method steps of adding power in stages include: performing the first adjustment with the maximum power step capability, and after a delay time t, linearly adding power with a slope k until reaching the target power.

In actual control, according to the power adjustment command of the unit and the current operating conditions, query the current maximum allowable power step and compare it with the power regulation command. If the maximum allowable step is greater than the power regulation command, the power step is directly performed jump adjustment. Otherwise, first perform power step control with the maximum allowable step amount, and after the standby unit runs stably, increase the power with a certain slope until the target power.

Specific examples:

In the absence of on-site measured data, the allowable value of the deviation between the actual speed of the unit during the transient process of fast power adjustment and the optimal speed is considered as ferrall less than ±80r/min (frequency deviation is ±4Hz), and the duration is less than 5s. The specific value still needs to be considered. Determined by on-site analysis. In the process of fast loading, the minimum allowable frequency shall not exceed 30Hz.

Based on the evaluation method proposed in this patent, under the condition of the minimum water head of 130m and the initial load of 4MW, the maximum power step of the unit is 0.54MW, the minimum frequency of the unit is 45.1Hz, the maximum frequency is 53.5Hz, and the frequency difference exceeds 4Hz The duration is 5s, and the proposed constraints are met. The power and frequency change curves are shown in Figure 4 and Figure 5.

As disclosed in this embodiment, by matching the real-time working condition data with the calculated maximum power step, and directly adjusting the full-power pumped-storage unit in real time according to the matched data, the fast power of the full-power pumped-storage unit is realized. The step adjustment capability enables the full-power pumped storage unit to fully exert the supporting capacity of rapid power.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the scope of the present invention. Protection scope, within the spirit and principles of the present invention, any modification, equivalent replacement, improvement, etc., shall be included in the protection scope of the present invention.

Claims (10)

1. A method for evaluating the maximum power step of a full-power pumped storage unit, characterized in that the method steps include: Obtaining a working condition data set, the working condition data set is a unit power data set and a head data set of a full-power pumped storage unit during operation; Construct the reduced-order active frequency response model of the pumped-storage unit, and calculate the frequency response curve of the reduced-order active frequency response model under power step excitation. and the equivalent model under the influence of the converter; According to the frequency response curve, calculate the maximum power step amount corresponding to each set of data in the working condition data set under the safety constraint condition, and obtain the maximum power step amount data set. 2. The method for evaluating the maximum power step of a full-power pumped storage unit according to claim 1, wherein the specific calculation method of the frequency response curve comprises: A reduced-order active frequency response model is constructed, a small-signal model is constructed according to the reduced-order active frequency response model, and a frequency response curve of the small-signal model is extracted under load step excitation. 3. The method for evaluating the maximum power step of a full-power pumped storage unit according to claim 1, wherein the method for calculating the maximum power step comprises: Calculate the power step corresponding to each set of data in the working condition data set according to the frequency response curve and the working condition data set; Judging whether the corresponding frequency in the frequency response curve satisfies the safety constraint condition, and if so, obtaining the maximum power step amount. 4. The method for evaluating the maximum power step of a full-power pumped storage unit according to claim 3, wherein the safety constraints specifically include: During the unit power step process, the highest frequency f _max is greater than the frequency limit f _maxall corresponding to the overspeed protection, but the duration t _over is less than the action delay t _overdelay of the overspeed protection; During the unit power step process, the minimum frequency f _min is less than the frequency limit f _minall corresponding to the underfrequency protection, but the duration t _low is less than the action delay t _lowdelay of the underfrequency protection; During the unit power step process, the absolute value of the deviation |f _err | between the actual frequency f _real and the optimal frequency f _opt of the unit is greater than the allowable frequency absolute value |f _errall |, but the duration t _err is less than the maximum tolerance time t _errdelay . 5. The method for evaluating the maximum power step of a full-power pumped-storage unit according to claim 1, wherein the reduced-order active frequency response model includes a governor, a water turbine, a generator and a constant power load, so The output end of the governor is connected to the input end of the water turbine, the output end of the water turbine is connected to the input end of the generator, and the output end of the generator outputs the actual power of the full-power pumped storage unit, and the The actual power and the reference frequency of the full-power pumped-storage unit are input to the governor, and the generator adopts a second-order model, and the load model adopts a constant power load model, which is connected in parallel at the generator end. 6. The method for evaluating the maximum power step of a full-power pumped-storage unit according to claim 5, wherein the hydraulic turbine adopts an equivalent model of initial operation head and load influence, and the specific expression is:

s is the Laplace operator; ΔPm is the mechanical power deviation of the turbine output; Δy is the guide vane opening deviation; T _wN is the water hammer time constant at the rated operating point; G _ht (s) is the transfer function of the turbine ; P _m0 is the initial steady-state value of the output mechanical power of the turbine, and h ₀ is the initial operating water head of the turbine. 7. The method for evaluating the maximum power step of a full-power pumped storage unit according to claim 2, wherein the specific expression of the small-signal model is:

X is the state variable of the small signal model, Y is the output variable of the small signal model, U is the input variable of the small signal model; A is the state matrix of the small signal model, B is the input matrix of the small signal model, and C is the small signal model The output matrix of D is the transmission matrix of the small signal model. 8. The method for evaluating the maximum power step of a full-power pumped storage unit according to claim 4, wherein the specific expression of the maximum power step is:

t is the time, t _s is the adjustment time required for the frequency deviation of the unit to be less than the maximum allowable frequency deviation after the power step, and △P is the power step amount. 9. A method for controlling the maximum power step of a full-power pumped storage unit, characterized in that the method steps include: Obtain real-time operating condition data and power adjustment instructions of full-power pumped storage units; Matching the working condition data with the maximum power step data set calculated by the evaluation method described in any one of claims 1 to 8 to obtain the maximum power step data corresponding to the working condition data; Based on the power adjustment command, it is judged whether the step capability of the maximum power step data is within the power regulation capability range, and if so, step-up power is directly applied to the full-power pumped storage unit, otherwise, step-wise power-up is performed. 10. The method for controlling the maximum power step of the full-power pumped-storage unit according to claim 9, characterized in that, the specific method steps of adding power in stages include: performing the first adjustment with the maximum power step capability , and after a delay time t, then linearly increase the power with a slope k until the target power is reached.

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