阅读说明：本技术 一种风力发电机组独立变桨控制方法和系统 (Independent variable pitch control method and system for wind generating set ) 是由 金强 蔡安民 林伟荣 焦冲 张俊杰 于 2021-09-28 设计创作，主要内容包括：本发明公开了一种风力发电机组独立变桨控制方法和系统,属于风力发电领域。通过检测三支叶片在旋转坐标系下的载荷及叶轮方位角,对风力发电机组进行状态空间建模,对其进行简化,在简化模型的基础上对风力发电机组的状态进行有效估计,将估计的状态进行全状态反馈并使用线性二次调节器对控制增益进行计算,最大程度避免多个单输入单输出回路之间耦合的影响,并兼顾控制成本与控制效果,在复杂风况下通过独立变桨提高机组在极端风况下的运行安全。本发明对不同叶轮方位角下的叶片模态塔架模态进行了线性化建模,克服了传统方式中采用单输入单输出多回路的方式,采用状态估计并使用线性二次调节器进行全状态反馈的方式来进行独立变桨控制。(The invention discloses an independent variable pitch control method and system for a wind generating set, and belongs to the field of wind power generation. The method comprises the steps of carrying out state space modeling on the wind generating set by detecting the load and the impeller azimuth angle of three blades under a rotating coordinate system, simplifying the model, effectively estimating the state of the wind generating set on the basis of the simplified model, carrying out full-state feedback on the estimated state and calculating control gain by using a linear secondary regulator, avoiding the influence of coupling among a plurality of single-input single-output loops to the greatest extent, considering the control cost and the control effect, and improving the operation safety of the wind generating set under the extreme wind condition through independent pitch control under the complex wind condition. The invention carries out linear modeling on the modal tower modes of the blade under different impeller azimuth angles, and overcomes the defects that the traditional mode adopts a single-input single-output multi-loop mode, and adopts a state estimation mode and a linear secondary regulator to carry out full-state feedback mode to carry out independent variable pitch control.)

1. An independent variable pitch control method of a wind generating set is characterized by comprising the following steps:

step 1) setting a detection period, detecting blade root load and an impeller azimuth angle of a blade of a wind turbine generator in the detection period, and establishing a rotating coordinate system;

step 2) establishing a linearization model based on the blade mode, the generator mode and the tower mode of the wind turbine generator; carrying out coordinate transformation on the blade root load under the rotating coordinate system to obtain a component under a non-rotating coordinate system, and carrying out state estimation on the linearized model based on the component under the non-rotating coordinate system;

step 3) calculating the control gain of the full-state negative feedback through the estimated state of the wind turbine generator, and further calculating to obtain a control instruction under a non-rotating coordinate system;

step 4) calculating an independent variable pitch angle instruction in a rotating coordinate system by the control instruction in the non-rotating coordinate system through coordinate inverse transformation;

and 5) detecting the rotating speed of the generator in a detection period, calculating a unified variable pitch angle instruction, combining the independent variable pitch angle instruction, calculating to obtain three blade variable pitch angle instructions, and performing variable pitch action based on the three blade variable pitch angle instructions.

2. The independent pitch control method of the wind generating set according to claim 1, wherein in the step 2), state bloom estimation is performed by combining a linearized model based on components in a non-rotational coordinate system, calculation is performed in a Kalman filtering manner, and a Ricatti equation is used for calculating gains of a Kalman filter.

3. The independent pitch control method of the wind generating set according to claim 1, wherein in step 3), the calculation of the control gain of the full-state negative feedback specifically comprises:

and (3) introducing a cost equation to balance the control cost, and then calculating the control gain of the full-state negative feedback by using a Riccati equation.

4. The independent pitch control method of the wind generating set according to claim 1, wherein in the step 4), the method further comprises limiting the amplitude of the independent pitch angle command.

5. The independent pitch control method of the wind generating set according to claim 1, wherein in the step 5), in the process of calculating the unified pitch angle command, the PID control of the rotating speed-pitch control loop is performed with the rotating speed of the generator as a target.

6. The independent pitch control method of the wind generating set according to claim 4, wherein in the step 5), the specific calculation process of the three blade pitch angle commands is as follows:

and superposing the independent variable pitch angle instructions after amplitude limiting with unified variable pitch angle instructions to obtain three blade variable pitch angle instructions, and transmitting the three blade variable pitch angle instructions to a variable pitch executing mechanism to perform variable pitch action so as to perform independent variable pitch load reduction and generator rotating speed control.

7. An independent variable pitch control system of a wind generating set is characterized by comprising:

the rotating coordinate system establishing unit is used for acquiring blade root loads and impeller azimuth angles of blades of the wind generating set in a detection period and establishing a rotating coordinate system;

the state estimation unit is interacted with the rotating coordinate system establishing unit and establishes a linear model based on the blade mode, the generator mode and the tower mode of the wind turbine; carrying out coordinate transformation on the blade root load under the rotating coordinate system to obtain a component under a non-rotating coordinate system, and carrying out state estimation on the linearized model based on the component under the non-rotating coordinate system;

the full-state negative feedback processing unit is interacted with the state estimation unit and used for calculating the control gain of full-state negative feedback and further calculating to obtain a control instruction under a non-rotating coordinate system;

and the variable pitch action control unit is interacted with the full-state negative feedback processing unit, detects the rotating speed of the generator in a detection period, calculates a unified variable pitch angle instruction, further calculates to obtain three blade variable pitch angle instructions, and performs variable pitch action based on the three blade variable pitch angle instructions.

8. The independent pitch control system of the wind generating set according to claim 7, wherein the pitch action control unit comprises an independent pitch angle instruction module for calculating the independent pitch angle instruction in the rotating coordinate system through coordinate inverse transformation of the control instruction in the non-rotating coordinate system; the three blade pitch angle instructions are obtained by combining and calculating the unified pitch angle instruction and the independent pitch angle instruction.

Technical Field

The invention belongs to the field of wind power generation, and relates to an independent variable pitch control method and system for a wind generating set.

Background

With the development of large-scale wind generating sets, the length of the blades and the height of the tower are increased continuously, the stress condition of each large component under different wind conditions is also complicated, and the ultimate load level is increased continuously. The problem of extreme load caused by the facing of complex wind conditions can be effectively solved by an advanced control strategy framework and a control strategy introduced by using a new sensor.

The existing technical scheme aiming at the problem comprises the following steps: and a load sensor is arranged at the root of the blade to detect the load of the blade root in real time. The coordinates are converted into a d-axis load component and a q-axis load component, two PID controllers are used for respectively taking the two load components as control inputs, and three different variable pitch angles are output to three variable pitch actuating mechanisms. However, the coupling phenomenon occurs in the two PID control loops, and the control system input noise and the measurement noise cannot be ignored. Meanwhile, the control gain can be set only by one-way adjustment, and the control cost and the control effect can not be considered at the same time.

Disclosure of Invention

The invention aims to overcome the defects that in the prior art, the traditional single-input single-output mode decomposes blade root loads of three blades into two shafts to be controlled respectively, but the mode of multiple control loops is easy to cause coupling, and the control gain cannot take into account two contradictory indexes of control cost and control deviation, and provides an independent variable pitch control method and system for a wind generating set.

In order to achieve the purpose, the invention adopts the following technical scheme to realize the purpose:

an independent variable pitch control method of a wind generating set comprises the following steps:

step 1) setting a detection period, detecting blade root load and an impeller azimuth angle of a blade of a wind turbine generator in the detection period, and establishing a rotating coordinate system;

step 2) establishing a linearization model based on the blade mode, the generator mode and the tower mode of the wind turbine generator; carrying out coordinate transformation on the blade root load under the rotating coordinate system to obtain a component under a non-rotating coordinate system, and carrying out state estimation on the linearized model based on the component under the non-rotating coordinate system;

step 3) calculating the control gain of the full-state negative feedback through the estimated state of the wind turbine generator, and further calculating to obtain a control instruction under a non-rotating coordinate system;

step 4) calculating an independent variable pitch angle instruction in a rotating coordinate system by the control instruction in the non-rotating coordinate system through coordinate inverse transformation;

and 5) detecting the rotating speed of the generator in a detection period, calculating a unified variable pitch angle instruction, combining the independent variable pitch angle instruction, calculating to obtain three blade variable pitch angle instructions, and performing variable pitch action based on the three blade variable pitch angle instructions.

Preferably, in step 2), based on components in a non-rotating coordinate system, performing state-bloom estimation by combining a linearized model, calculating in a kalman filtering manner, and calculating a gain of a kalman filter by using a ricitti equation.

Preferably, in step 3), calculating the control gain of the full-state negative feedback specifically includes:

and (3) introducing a cost equation to balance the control cost, and then calculating the control gain of the full-state negative feedback by using a Riccati equation.

Preferably, in the step 4), amplitude limiting is further performed on the independent pitch angle command.

Preferably, in the step 5), during the calculation of the unified pitch angle command, the PID control of the rotation speed-pitch control loop is performed with the control of the rotation speed of the generator as a target.

Preferably, in step 5), the specific calculation process of the three blade pitch angle commands is as follows:

and superposing the independent variable pitch angle instructions after amplitude limiting with unified variable pitch angle instructions to obtain three blade variable pitch angle instructions, and transmitting the three blade variable pitch angle instructions to a variable pitch executing mechanism to perform variable pitch action so as to perform independent variable pitch load reduction and generator rotating speed control.

An independent pitch control system of a wind generating set, comprising:

the rotating coordinate system establishing unit is used for acquiring blade root loads and impeller azimuth angles of blades of the wind generating set in a detection period and establishing a rotating coordinate system;

the state estimation unit is interacted with the rotating coordinate system establishing unit and establishes a linear model based on the blade mode, the generator mode and the tower mode of the wind turbine; carrying out coordinate transformation on the blade root load under the rotating coordinate system to obtain a component under a non-rotating coordinate system, and carrying out state estimation on the linearized model based on the component under the non-rotating coordinate system;

the full-state negative feedback processing unit is interacted with the state estimation unit and used for calculating the control gain of full-state negative feedback and further calculating to obtain a control instruction under a non-rotating coordinate system;

and the variable pitch action control unit is interacted with the full-state negative feedback processing unit, detects the rotating speed of the generator in a detection period, calculates a unified variable pitch angle instruction, further calculates to obtain three blade variable pitch angle instructions, and performs variable pitch action based on the three blade variable pitch angle instructions.

Preferably, the variable pitch motion control unit comprises an independent variable pitch angle instruction module, which is used for calculating the independent variable pitch angle instruction in the rotating coordinate system through coordinate inverse transformation of the control instruction in the non-rotating coordinate system; the three blade pitch angle instructions are obtained by combining and calculating the unified pitch angle instruction and the independent pitch angle instruction.

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

the invention provides an independent variable pitch control method of a wind generating set, which is characterized in that the state space modeling of the wind generating set is carried out by detecting the load and the impeller azimuth angle of three blades under a rotating coordinate system, the state space modeling is simplified, the state of the wind generating set is effectively estimated on the basis of the simplified model, the estimated state is subjected to full-state feedback, and the control gain is calculated by using a linear secondary regulator, so that the influence of coupling among a plurality of single-input single-output loops is avoided to the greatest extent, the control cost and the control effect are considered, and the operation safety of the wind generating set under the extreme wind condition is improved by the independent variable pitch under the complex wind condition. The invention carries out linear modeling on the modal tower modes of the blade under different impeller azimuth angles, overcomes the defect that the traditional mode adopts a single-input single-output multi-loop mode, and innovatively adopts a mode of state estimation and full-state feedback by using a linear secondary regulator to carry out independent variable pitch control.

The invention also discloses an independent variable pitch control system of the wind generating set, which replaces the existing scheme of independent variable pitch, thereby avoiding the influence on the control effect caused by the input noise and the measurement noise due to the coupling among multiple loops. Meanwhile, a unit linearization model can be estimated according to the collected blade root load signal, the impeller azimuth angle signal, the tower displacement signal and the like, and the unit state information can be estimated more accurately according to the model, so that more accurate feedback closed-loop control can be performed.

Drawings

FIG. 1 is a flow chart of an independent pitch control method of a wind generating set based on a linear secondary regulator;

FIG. 2 is a control architecture diagram of the linear quadratic regulator + Kalman filter.

Detailed Description

The invention is described in further detail below with reference to the accompanying drawings:

example 1

An independent variable pitch control method of a wind generating set comprises the following steps:

step 1) setting a detection period, detecting blade root load and an impeller azimuth angle of a blade of a wind turbine generator in the detection period, and establishing a rotating coordinate system;

step 2) establishing a linearization model based on the blade mode, the generator mode and the tower mode of the wind turbine generator; carrying out coordinate transformation on the blade root load under the rotating coordinate system to obtain a component under a non-rotating coordinate system, and carrying out state estimation on the linearized model based on the component under the non-rotating coordinate system;

step 3) calculating the control gain of the full-state negative feedback through the estimated state of the wind turbine generator, and further calculating to obtain a control instruction under a non-rotating coordinate system;

step 4) calculating an independent variable pitch angle instruction in a rotating coordinate system by the control instruction in the non-rotating coordinate system through coordinate inverse transformation;

and 5) detecting the rotating speed of the generator in a detection period, calculating a unified variable pitch angle instruction, combining the independent variable pitch angle instruction, calculating to obtain three blade variable pitch angle instructions, and performing variable pitch action based on the three blade variable pitch angle instructions.

Example 2

An independent variable pitch control method of a wind generating set comprises the following steps:

detecting blade root loads and impeller azimuth angles of three blades in a current detection period, carrying out linear modeling on the whole generator set, simultaneously carrying out coordinate transformation on the blade root loads in a rotating coordinate system, converting the blade root loads into components in a non-rotating coordinate system, carrying out state estimation on the components by combining the components with a built linear model, calculating the state estimation in a Kalman filtering mode, and calculating the gain of a Kalman filter by using a Riccati equation.

After the estimated state of the wind generating set is obtained, a full-state negative feedback mode is used, a cost equation is introduced to balance the control cost and the control effect, and a Riccati equation is used for calculating the control gain of the full-state negative feedback to calculate the control instruction under a non-rotating coordinate system.

And calculating the independent variable pitch angle instruction in the rotating coordinate system according to the control instruction in the non-rotating coordinate system through coordinate inverse transformation. And carrying out amplitude limiting on the independent pitch angle instruction.

And detecting the rotating speed of the generator in the current detection period, carrying out PID control on a rotating speed-variable pitch loop by taking the rotating speed of the generator as a target, and calculating a unified variable pitch angle instruction.

And superposing the independent variable pitch angle instructions after amplitude limiting with unified variable pitch angle instructions to obtain final three blade variable pitch angle instructions, and transmitting the final three blade variable pitch angle instructions to a variable pitch actuating mechanism for variable pitch action so as to perform independent variable pitch load reduction and generator rotating speed control.

Example 3

An independent pitch control method of a wind generating set is shown in fig. 1, and comprises the following steps:

1) the nonlinear aerodynamic equation of motion of the wind generating set can be described asWherein M is a mass matrix, f is a nonlinear equation of motion,respectively displacement, speed and acceleration of the variable of the degree of freedom of the wind generating set,uin order to control the input vector, _duan interference vector is input for the wind, and t is time.

2) By pairsAt the operating point, a slight perturbation (Δ) is made, which is recorded asWhere op is denoted as the operating point.

3) Taylor expansion is carried out on the formula of the first step with the slight perturbation of the second step on the operating point to form a second-order linearized equation, andto be provided withSubstitution to obtain the state space equationWherein A is_RIs a state matrix, B_RAs an input matrix, B_dRFor wind input of interference matrix, D_dRConverting the matrix for wind input, x_RIs a state variable, u_RAs an input variable, y_RAs an output variable, w_RFor wind input of disturbance variable, v_RFor measuring noise, the subscript R represents a rotating coordinate system, meaning that it is time-varying.

4) Since the above state space equation is time-varying, it needs to be converted into a non-rotational coordinate system in order to apply a linear time-invariant model.

5) The b-th blade wheel azimuth may be expressed as: Ψ_bΨ + (b-1) × (2 × pi/3). Where b is the number of blades and Ψ is the impeller azimuth. Defined as Ψ -0 with the first blade facing vertically upward.

6) Since the non-rotating coordinate system is a projection of the rotating coordinate system, the rotating coordinate system of the three blades can be converted into the non-rotating coordinate system of the two axes in the relationshipWherein q is₀In a unified mode, q_cIn cos cycle mode, q_sIn sin loop mode. Marking this as a transformation matrix, and taking x in the state space equation of the first step_R＝T_s(Ψ)x_NR，u_R＝T_c(Ψ)u_NR，y_R＝T_o(Ψ)y_NRThe state space equation after conversion can be obtained asWhere NR represents a non-rotating coordinate system.

7) Since it has been converted to a weak impeller azimuth correlation, averaging each impeller azimuth can yield a linear time-invariant state space equation without missing important modal information, and is recorded as

8) In this embodiment, the degree of freedom of the wind turbine generator system represented by q may be selected from the flapwise displacement of the blades 1, 2, and 3, the azimuth of the impeller, and the first-order forward-backward displacement of the tower. The u input variable is selected as three blade pitch angles beta₁，β₂，β₃。

9) The LQG algorithm in the multi-input multi-output control framework is introduced to solve the problem of mutual coupling of multiple control loops. And (4) recording w and v in the state space equation obtained in the step 7 as wind input interference noise and measurement noise, wherein the w and v are zero mean Gaussian white noise, and the w and v are not related to each other.

10) LQG optimal control uses the least control cost to obtain the least control deviation, so a cost equation is introducedWherein Q represents the state trade-off matrix, R represents the input trade-off matrix, and both matrices are defined as semi-positive, i.e., Q ═ Q^TNot less than 0 and R ═ R^TIs more than or equal to 0. The two matrices represent control matrices that balance fast control and low control cost, respectively, with the least cost equation as the control objective.

11) The cost equation in the step 10 leads out the relation K between the state variable and the input variable to be determined_cUsing an all-state negative feedback relationship, i.e. a linear quadratic regulator, denoted as u-K_cx. Wherein K_c＝R^-1B^TP_cIn which P is_cIs also a semi-positive definite matrix, P_c＝P_c ^T≥0，P_cIs obtained by calculating the Ricitti equation with the formula of A^TP_c+P_cA-P_cBR^-1B^TP_c+M^TQM＝0。

12) Since the 11 th step needs full-state feedback, the state variables are estimated by a Kalman filter to be recorded as the state of the wind generating setIts Kalman gain is given by K_f＝P_fC^TV^-1With the aim of reducing Wherein P is_fIs also a semi-positive definite matrix, P_f＝P_f ^T≥0，P_cIs obtained by calculating the Ricitti equation with the formula P_fA^T+AP_f-P_fC^TV^-1CP_f+B_dWB_d ^T＝0。

13) The state of the wind generating set can be estimated by the model obtained by the linearization in the step 7, and the formula isLinear quadratic regulator u ═ K_cx and y ═ Cx + Du + D_av instead of the entire LQG control framework available asWherein, A is a system state coefficient matrix, B is a system control coefficient matrix, C is an output state coefficient matrix, D is an output control coefficient matrix, Kf is a state estimation gain, Kc is an all-state feedback gain, x is a system state vector, y is a system output vector, and w is a noise input vector.

14) By means of a linear quadratic regulator u-K_cx is still in the non-rotating coordinate system, so the independent pitch angle instruction in the rotating coordinate system needs to be obtained by coordinate inverse transformation on the control instruction in the non-rotating coordinate system.

15) And after amplitude limiting is carried out on the three different independent variable pitch angle instructions, the same unified variable pitch angle instruction is superposed to obtain a final variable pitch angle instruction, and the final variable pitch angle instruction is sent to a variable pitch executing mechanism to carry out variable pitch action so as to complete independent variable pitch control.

With reference to FIG. 2, y represents the output of the wind turbine, and u represents the control input of the wind turbine, which is defined by the control gain-Kc and the estimated system state vectorThe product is obtained. This is a full state negative feedback. The estimated system state vector can be obtained by combining A, B, C, D and Kf with the equation of step 13When obtaining the estimated system state vectorAnd controlThe control gain-Kc can be derived from the control input u of the overall control algorithm.

Example 4

An independent pitch control system of a wind generating set, comprising:

the linear model establishing unit is used for acquiring blade root load and an impeller azimuth angle of blades of the wind turbine generator set in a detection period and establishing a linear model;

the state estimation unit is used for carrying out coordinate transformation on the blade root load under the rotating coordinate system to obtain a component under a non-rotating coordinate system and carrying out state estimation on the linearized model;

the full-state negative feedback processing unit is interacted with the state estimation unit and used for calculating the control gain of full-state negative feedback and further calculating to obtain a control instruction under a non-rotating coordinate system;

the variable pitch action control unit detects the rotating speed of the generator in a detection period, calculates a unified variable pitch angle instruction, calculates three blade variable pitch angle instructions by combining the independent variable pitch angle instruction, and performs variable pitch action based on the three blade variable pitch angle instructions.

The invention innovatively introduces a multi-input multi-output mode, simplifies and models a nonlinear strong-coupling time-varying wind generating set model, converts the model under a rotating coordinate system into a non-rotating coordinate system in a coordinate conversion mode, effectively estimates the state in the set by utilizing a linearized model, and performs full-state feedback on the estimated state, wherein the control gain is calculated by adopting a cost equation, so that the problem of contradiction between the control cost and the control deviation can be effectively solved, namely, the life of a variable pitch actuator can be considered while the load reduction problem is solved. And (3) performing amplitude limiting operation, for example, when the calculated independent pitch instruction exceeds 50% of the unified pitch instruction, the maximum output instruction value is 50% of the unified pitch instruction.

It should be noted that, since the three blades rotate continuously, the measured blade root load changes continuously with the azimuth angle of the impeller, and the rotating coordinate system represents a coordinate system that changes with time and changes with the azimuth angle of the impeller. After modeling and linearly simplifying the motion equations including the blade mode, the generator mode, the tower mode and the like, the state can be estimated because the motion equations already contain relevant mode information. The step of calculating the unified variable pitch angle instruction specifically comprises the following steps: the rotating speed of the generator is kept at the rated rotating speed by changing the pitch by adopting a PID or PI control mode, so that the control input is the rotating speed of the generator, the control algorithm is PID or PI, and the control output is a pitch angle instruction (three blades are consistent).

The method adopts the impeller azimuth angle averaging mode in the process of converting the rotating coordinate system into the non-rotating coordinate system, the more impeller azimuth angles are divided, the larger the calculation amount of the linearization process is, but the method is not limited to, and other methods do not adopt the impeller azimuth angle averaging mode, namely, do not consider the difference of state space equations under different impeller azimuth angles within 360 degrees. The method for controlling the pitch angles of three different blades by considering the unbalanced load is not limited to this method, and other methods such as torque control may be included. In the linearization process, only the blade flap direction mode, the tower first-order mode and the generator rotation state are included, so that the number of the state variables is 10, but the method is not limited to this, and other modes such as the blade mode and the tower mode including higher orders adopt more state variables so that the linearization model includes more mode information. The full-state negative feedback method adopted in the process of using the linear quadratic regulator is not limited to the method, and other methods such as partial-state feedback, positive feedback and the like. The method is characterized in that a unified variable pitch instruction given by a traditional rotating speed variable pitch single-input single-output control loop is superposed with a multi-input multi-output controller to give an independent variable pitch mode, but the method is not limited to the mode, and other modes such as a multi-input multi-output mode are adopted to control the rotating speed of a generator and the load of a blade root simultaneously. The method of using the root load of three rotating blades is adopted, but the method is not limited to the method, and other methods such as directly acquiring the bearing load and the tower load in a non-rotating coordinate system.

In summary, the invention provides a method for controlling the independent pitch variation of the wind generating set based on the linear secondary regulator, which replaces the existing scheme of the independent pitch variation, thereby avoiding the influence on the control effect caused by the input noise and the measurement noise due to the coupling among multiple loops. Meanwhile, a unit linearization model can be estimated according to the collected blade root load signal, the impeller azimuth angle signal, the tower displacement signal and the like, and the unit state information can be estimated more accurately according to the model, so that more accurate feedback closed-loop control can be performed. The invention designs a method for controlling the independent variable pitch of a wind generating set based on a linear secondary regulator, so that the independent variable pitch control can be more accurately carried out by combining the state estimation of Kalman filtering and the closed loop feedback of the linear secondary regulation according to the measured blade root load. The invention innovatively adopts Kalman filtering to carry out state estimation and uses a linear secondary regulator to carry out state control according to the state estimation, and combines a multi-input multi-output control framework on the basis of the original independent variable pitch control, thereby avoiding the problems of multi-loop coupling, non-compromise of control cost and effect, and non-consideration of system input and measurement noise.

The above-mentioned contents are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any modification made on the basis of the technical idea of the present invention falls within the protection scope of the claims of the present invention.