阅读说明：本技术 基于轴系转速的汽轮机组暂态扭矩保护方法与装置 (Turboset transient torque protection method and device based on shafting rotating speed ) 是由 谢小荣 刘朋印 于 2019-09-29 设计创作，主要内容包括：本发明公开了一种基于轴系转速的汽轮机组暂态扭矩保护方法与装置,其中,方法包括以下步骤：利用滤波器对机组轴系转速信号进行滤波,得到机组的当前模态转速；利用当前模态转速进行暂态扭矩辨识,得到暂态扭矩辨识值；若当前模态转速大于第一预设值,则判断暂态扭矩辨识值是否大于第二预设值；若暂态扭矩辨识值大于第二预设值,且处于持续增长状态,则发出跳闸指令,以切除当前机组。该方法可以避免扭矩过大对机组轴系产生损坏,保障汽轮发电机组轴系安全,有效解决汽轮机组与串联电容补偿输电网之间的SSR问题。(The invention discloses a method and a device for protecting transient torque of a steam turbine set based on shafting rotating speed, wherein the method comprises the following steps: filtering the rotating speed signal of the shafting of the unit by using a filter to obtain the current modal rotating speed of the unit; performing transient torque identification by using the current modal rotating speed to obtain a transient torque identification value; if the current modal rotating speed is larger than a first preset value, judging whether the transient torque identification value is larger than a second preset value; and if the transient torque identification value is larger than the second preset value and is in a continuous increasing state, a tripping command is sent out to cut off the current unit. The method can avoid damage to the shafting of the turbine generator set due to overlarge torque, ensure the safety of the shafting of the turbine generator set and effectively solve the SSR problem between the turbine generator set and the series capacitance compensation power transmission network.)

1. A transient torque protection method of a turboset based on a shafting rotating speed is characterized by comprising the following steps:

filtering the rotating speed signal of the shafting of the unit by using a filter to obtain the current modal rotating speed of the unit;

performing transient torque identification by using the current modal rotating speed to obtain a transient torque identification value;

if the current modal rotating speed is larger than a first preset value, judging whether a transient torque identification value is larger than a second preset value; and

and if the transient torque identification value is larger than a second preset value and is in a continuous increasing state, a tripping command is sent out to cut off the current unit.

2. The method of claim 1, wherein the step of issuing a trip command if the transient torque identification value is greater than a second predetermined value and in a continuously increasing state comprises:

judging whether the transient torque identification value is larger than the second preset value or not;

if the current cycle torque peak value is larger than the second preset value, delaying one cycle to judge whether the current cycle torque peak value is in a continuous increasing state or not according to the current cycle torque peak value and the previous cycle torque peak value;

and if the continuously increasing state is adopted, generating the tripping instruction.

3. The method according to claim 1, wherein the performing transient torque identification according to the current modal speed to obtain a transient torque identification value comprises:

converting the current modal rotating speed into a modal rotating speed signal of a shafting position corresponding to the torque;

integrating modal rotating speed signals of a shafting position corresponding to the torque to obtain a torsion angle corresponding to each mode;

converting the torsion angles corresponding to the modes into electric torsion angles of the mass relative to a synchronous rotation coordinate system;

and solving the torque between the shaft sections according to the electric torsion angle of the mass relative to the synchronous rotating coordinate system.

4. The method of claim 3, wherein the modal speed signal is converted by the formula:

ω^(m)＝ω./k，

wherein, omega is the current mode rotating speed,/is defined as the division of the corresponding elements of the matrix, and k is the coefficient row vector;

for omega^(m)Integrating to obtain the torsion angle delta corresponding to each mode^(m)；

The conversion formula of the electric torsion angle is as follows:

[δ₁ δ₂ … δ_n-1 δ_n]^T＝Q·[δ₁ ^(m) δ₂ ^(m) … δ_n-1 ^(m) 0]^T，

where Q is the coefficient matrix, δ^(m)The twist angle corresponding to each mode is δ is the electrical twist angle.

5. The method of claim 4, wherein the torque between the shaft segments is calculated by the formula:

T_ij＝K_ij(δ_i-δ_j)，

wherein, K_ijRepresenting the spring constant between the shaft segments.

6. The utility model provides a turboset transient state moment of torsion protection device based on shafting rotational speed which characterized in that includes:

the modal rotating speed acquisition module is used for filtering the rotating speed signal of the shafting of the unit by using the filter to obtain the current modal rotating speed of the unit;

the transient torque identification module is used for identifying transient torque by using the current modal rotating speed to obtain a transient torque identification value;

the starting logic module is used for judging whether the transient torque identification value is larger than a second preset value or not when the current modal rotating speed is larger than a first preset value; and

and the protection criterion module is used for sending a tripping command to cut off the current unit when the transient torque identification value is larger than a second preset value and is in a continuous increasing state.

7. The apparatus of claim 6, wherein the protection criterion module is further configured to determine whether the transient torque identification value is greater than the second predetermined value; if the current cycle torque peak value is larger than the second preset value, delaying one cycle to judge whether the current cycle torque peak value is in a continuous increasing state or not according to the current cycle torque peak value and the previous cycle torque peak value; and if the continuously increasing state is adopted, generating the tripping instruction.

8. The apparatus of claim 6, wherein the transient torque recognition module is further configured to convert the current modal rotation speed into a modal rotation speed signal of a shafting position corresponding to a torque; integrating modal rotating speed signals of a shafting position corresponding to the torque to obtain a torsion angle corresponding to each mode; converting the torsion angles corresponding to the modes into electric torsion angles of the mass relative to a synchronous rotation coordinate system; and solving the torque between the shaft sections according to the electric torsion angle converted into the mass relative to the synchronous rotating coordinate system.

9. The apparatus of claim 8, wherein the modal speed signal is transformed by the formula:

ω^(m)＝ω./k，

wherein, omega is the current mode rotating speed,/is defined as the division of the corresponding elements of the matrix, and k is the coefficient row vector;

for omega^(m)Integrating to obtain the torsion angle delta corresponding to each mode^(m)(ii) a The conversion formula of the electric torsion angle is as follows:

[δ₁ δ₂ … δ_n-1 δ_n]^T＝Q·[δ₁ ^(m) δ₂ ^(m) … δ_n-1 ^(m) 0]^T，

where Q is the coefficient matrix, δ^(m)The twist angle corresponding to each mode is δ is the electrical twist angle.

10. The apparatus of claim 9, wherein the torque between the shaft segments is calculated by the formula:

T_ij＝K_ij(δ_i-δ_j)，

wherein, K_ijRepresenting the spring constant between the shaft segments.

Technical Field

The invention relates to the technical field of power system protection, in particular to a method and a device for protecting transient torque of a steam turbine set based on shafting rotating speed.

Background

Long-distance and large-capacity power transmission is an objective requirement for the development of the power industry in China, and the series capacitance compensation technology is more and more widely applied to the purposes of improving the transmission capacity of a long-distance power transmission line and improving the stability of a system. However, the interaction between the turbo generator set and the series capacitance compensation power transmission network causes a problem of the stability of the sub-synchronous frequency range, namely, a sub-synchronous resonance (SSR) problem. When the SSR problem occurs, higher transient torque and stress can be generated among all the blocks of the unit shafting, so that the fatigue life loss is caused, and the service life of the unit shafting is reduced; under extreme conditions, the transient torque of a shafting of the unit is too large, and even the large shaft of the unit is broken, so that serious equipment and even personal safety accidents are caused.

In order to ensure the shafting safety of the steam turbine generator unit, ensure that the shafting of the steam turbine generator unit does not generate excessive fatigue life loss when the SSR problem occurs, and avoid the problem of one-time fracture of the large shaft of the steam turbine generator unit, some protection methods such as TSR (torsion stress relay) have been proposed in the prior art. However, the TSR has a long delay (about 0.5s) in response, cannot reflect the impact torque generated by the shaft system when the unit generates the SSR, and can only act when the unit torque diverges. However, too large impact torque of the unit can also cause too large fatigue life loss of the shafting of the unit, and even cause one-time fracture of the large shaft of the unit. Therefore, it is necessary to develop a transient torque protection technique and device for a steam turbine set with faster response speed and higher reliability.

Disclosure of Invention

The present invention is directed to solving, at least to some extent, one of the technical problems in the related art.

Therefore, the invention aims to provide a transient torque protection method of a steam turbine set based on the rotating speed of the shafting, which can avoid damage to the shafting of the set due to overlarge torque, ensure the safety of the shafting of the steam turbine set and effectively solve the SSR problem between the steam turbine set and a series capacitance compensation power transmission network.

The invention also aims to provide a transient torque protection device of the steam turbine set based on the rotating speed of the shafting.

In order to achieve the above object, an embodiment of the present invention provides a transient torque protection method for a steam turbine set based on a shafting rotation speed, including the following steps: filtering the rotating speed signal of the shafting of the unit by using a filter to obtain the current modal rotating speed of the unit; performing transient torque identification by using the current modal rotating speed to obtain a transient torque identification value; if the current modal rotating speed is larger than a first preset value, judging whether a transient torque identification value is larger than a second preset value; and if the transient torque identification value is larger than a second preset value and is in a continuous increasing state, a tripping command is sent out to cut off the current unit.

According to the transient torque protection method of the steam turbine set based on the shafting rotating speed, disclosed by the embodiment of the invention, based on modal rotating speed acquisition and transient torque identification, firstly, filtering is carried out on the shafting rotating speed of the steam turbine set by using a filter to obtain the modal rotating speed of the steam turbine set; then, a transient torque of the unit is obtained by utilizing a torque identification link; and finally, judging whether a tripping instruction is sent out or not by utilizing a protection criterion to disconnect the unit from the power grid, thereby avoiding the damage of the unit shafting caused by overlarge torque, ensuring the safety of the turboset shafting and effectively solving the SSR problem between the turboset and the series capacitance compensation power transmission network.

In addition, the transient torque protection method for the turboset based on the shafting rotating speed according to the embodiment of the invention can also have the following additional technical characteristics:

further, in an embodiment of the present invention, if the transient torque identification value is greater than a second preset value and is in a continuously increasing state, the issuing a trip command includes: judging whether the transient torque identification value is larger than the second preset value or not; if the current cycle torque peak value is larger than the second preset value, delaying one cycle to judge whether the current cycle torque peak value is in a continuous increasing state or not according to the current cycle torque peak value and the previous cycle torque peak value; and if the continuously increasing state is adopted, generating the tripping instruction.

Further, in an embodiment of the present invention, the performing transient torque identification according to the current modal rotation speed to obtain a transient torque identification value includes: converting the current modal rotating speed into a modal rotating speed signal of a shafting position corresponding to the torque; integrating modal rotating speed signals of a shafting position corresponding to the torque to obtain a torsion angle corresponding to each mode; converting the torsion angles corresponding to the modes into electric torsion angles of the mass relative to a synchronous rotation coordinate system; and solving the torque between the shaft sections according to the electric torsion angle of the mass relative to the synchronous rotating coordinate system.

Further, in an embodiment of the present invention, the conversion formula of the modal rotation speed signal is:

ω^(m)＝ω./k，

wherein, omega is the current mode rotating speed,/is defined as the division of the corresponding elements of the matrix, and k is the coefficient row vector;

for omega^(m)Integrating to obtain the torsion angle delta corresponding to each mode^(m)；

The conversion formula of the electric torsion angle is as follows:

[δ₁ δ₂ … δ_n-1 δ_n]^T＝Q·[δ₁ ^(m) δ₂ ^(m) … δ_n-1 ^(m) 0]^T，

where Q is the coefficient matrix, δ^(m)The twist angle corresponding to each mode is δ is the electrical twist angle.

Further, in one embodiment of the present invention, the torque between the shaft segments is calculated by the formula:

T_ij＝K_ij(δ_i-δ_j)，

wherein, K_ijRepresenting the spring constant between the shaft segments.

In order to achieve the above object, an embodiment of the present invention provides a transient torque protection device for a steam turbine set based on a rotational speed of a shaft system, including: the modal rotating speed acquisition module is used for filtering the rotating speed signal of the shafting of the unit by using the filter to obtain the current modal rotating speed of the unit; the transient torque identification module is used for identifying transient torque by using the current modal rotating speed to obtain a transient torque identification value; the starting logic module is used for judging whether the transient torque identification value is larger than a second preset value or not when the current modal rotating speed is larger than a first preset value; and the protection criterion module is used for sending a tripping command to cut off the current unit when the transient torque identification value is larger than a second preset value and is in a continuous increasing state.

According to the transient torque protection device of the steam turbine set based on the shafting rotating speed, disclosed by the embodiment of the invention, based on modal rotating speed acquisition and transient torque identification, firstly, filtering is carried out on the shafting rotating speed of the steam turbine set by using a filter to obtain the modal rotating speed of the steam turbine set; then, a transient torque of the unit is obtained by utilizing a torque identification link; and finally, judging whether a tripping instruction is sent out or not by utilizing a protection criterion to disconnect the unit from the power grid, thereby avoiding the damage of the unit shafting caused by overlarge torque, ensuring the safety of the turboset shafting and effectively solving the SSR problem between the turboset and the series capacitance compensation power transmission network.

In addition, the transient torque protection device for the turboset based on the shafting rotating speed according to the embodiment of the invention can also have the following additional technical characteristics:

further, in an embodiment of the present invention, the protection criterion module is further configured to determine whether the transient torque identification value is greater than the second preset value; if the current cycle torque peak value is larger than the second preset value, delaying one cycle to judge whether the current cycle torque peak value is in a continuous increasing state or not according to the current cycle torque peak value and the previous cycle torque peak value; and if the continuously increasing state is adopted, generating the tripping instruction.

Further, in an embodiment of the present invention, the transient torque identification module is further configured to convert the current modal rotation speed into a modal rotation speed signal of a shafting position corresponding to a torque; integrating modal rotating speed signals of a shafting position corresponding to the torque to obtain a torsion angle corresponding to each mode; converting the torsion angles corresponding to the modes into electric torsion angles of the mass relative to a synchronous rotation coordinate system; and solving the torque between the shaft sections according to the electric torsion angle of the mass relative to the synchronous rotating coordinate system.

Further, in an embodiment of the present invention, the conversion formula of the modal rotation speed signal is:

ω^(m)＝ω./k，

wherein, omega is the current mode rotating speed,/is defined as the division of the corresponding elements of the matrix, and k is the coefficient row vector;

for omega^(m)Integrating to obtain the torsion angle delta corresponding to each mode^(m)；

The conversion formula of the electric torsion angle is as follows:

[δ₁ δ₂ … δ_n-1 δ_n]^T＝Q·[δ₁ ^(m) δ₂ ^(m) … δ_n-1 ^(m) 0]^T，

where Q is the coefficient matrix, δ^(m)The twist angle corresponding to each mode is δ is the electrical twist angle.

Further, in one embodiment of the present invention, the torque between the shaft segments is calculated by the formula:

T_ij＝K_ij(δ_i-δ_j)，

wherein, K_ijRepresenting the spring constant between the shaft segments.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The foregoing and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a schematic diagram of an overall scheme according to an embodiment of the present invention;

FIG. 2 is a flow chart of a transient torque protection method for a steam turbine set based on shafting rotational speed according to an embodiment of the present invention;

FIG. 3 is a flow chart of a modal rotation speed link implementation method according to an embodiment of the invention;

fig. 4 is a schematic structural diagram of a transient torque protection device of a steam turbine set based on a shafting rotation speed according to an embodiment of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

The technical scheme of the embodiment of the invention is as shown in fig. 1, and the method mainly comprises four links of modal rotating speed acquisition, starting logic, transient torque identification and protection criterion based on modal rotating speed acquisition and transient torque identification.

The basic principle of the implementation of the scheme is as follows: a modal rotating speed obtaining link: obtaining the shafting rotating speed (the rotating speed of a machine head or a machine tail) of the machine set by using a rotating speed sensor, and filtering the rotating speed signal to obtain a modal rotating speed signal of the machine set; starting a logic link: judging whether to send out a starting signal or not according to the modal rotating speed; transient torque identification link: calculating transient torque of the unit by using a unit modal rotating speed signal and a unit shafting parameter; a protection criterion link: when the starting signal exists, the protection criterion judges whether a tripping command needs to be sent according to the torque identification value. When the transient torque of the shafting of the steam turbine generator unit exceeds a preset value and is in a continuous increasing state, the protection device sends a tripping command to disconnect the unit from the power grid, and the phenomenon that the shafting of the unit is greatly damaged due to overlarge torque is avoided.

The method and the device for transient torque protection of a steam turbine set based on shafting rotation speed according to an embodiment of the present invention are described below with reference to the accompanying drawings.

FIG. 2 is a flow chart of a transient torque protection method for a steam turbine set based on shafting rotational speed according to an embodiment of the present invention.

As shown in fig. 2, the transient torque protection method for a steam turbine set based on the shafting rotation speed includes the following steps:

in step S201, the filter is used to filter the rotating speed signal of the shafting of the unit, so as to obtain the current modal rotating speed of the unit.

It can be understood that, in the embodiment of the present invention, the rotation speed sensor is used to obtain the rotation speed signal, and the filter is used to filter the rotation speed signal of the shafting of the unit to obtain the modal rotation speed of the unit in each mode.

Specifically, as shown in fig. 1, a modal rotation speed obtaining link

The main function of the modal rotation speed acquisition link is to convert a rotation speed pulse signal acquired by a rotation speed sensor into a rotation speed digital signal under each mode by using a filter, and the implementation method is as shown in fig. 3, and specifically includes:

(1) signal conversion

The main function of the signal conversion is to convert the pulse quantity of the rotating speed signal acquired by the rotating speed sensor into a digital signal, and then the digital signal is used for filtering.

(2) Low-pass, high-pass filter

The low-pass filter and the high-pass filter are mainly used for filtering direct-current components, low-frequency components and power frequency components in the rotating speed signal and ensuring that the obtained modal rotating speed is more accurate. The characteristic frequency of the low-pass filter and the high-pass filter needs to avoid the modal frequency of the unit, and the modal rotating speed signal obtained by filtering is ensured not to be distorted.

For example, the high-pass filter may have a characteristic frequency of 10Hz and the low-pass filter may have a characteristic frequency of 40 Hz.

(3) Band-pass and band-stop filter

The rotating speed signals filtered by the low-pass filter and the high-pass filter pass through the band-pass filter and the band-stop filter to obtain modal rotating speed signals under various modes. In designing a band-pass, band-stop filter, the characteristic frequency and bandwidth of a given filter are required. Wherein the characteristic frequency is the modal frequency of the unit; the selection principle of the bandwidth is that the signals obtained by the band-pass and band-stop filters must be modal rotating speed signals under single modal frequency. There are many design methods for designing band-pass and band-stop filters, and the common design methods include FIR filters, chebyshev filters, bezier filters, elliptic filters, and the like.

In addition, the steam turbine set containing n masses corresponds to n-1 modes in total, and the method for acquiring the mode rotating speed signal is described by taking one mode as an example:

first, the signal passes through at ω₁Obtaining a modal rotation speed signal for a band-pass filter of the characteristic frequency; then, respectively by the following equation₂、ω₃…ω_n-1The filter is a band elimination filter of characteristic frequency, and eliminates the influence of other modal frequency signals.

Then, the rotating speed signal is filtered by a band-pass filter and a band-stop filter, so that accurate modal rotating speed signals under various modal frequencies can be obtained.

In step S202, transient torque identification is performed using the current mode rotation speed to obtain a transient torque identification value.

It can be appreciated that after obtaining the modal rotation speed, embodiments of the present invention perform transient torque identification, determining the start-up logic. That is, the embodiment of the present invention may calculate the transient torque by using the modal rotation speed, and determine the start logic, wherein the start logic is described in detail below and is not described in detail herein. Step S202 is a transient torque identification step shown in fig. 1: and solving the torque between the shaft sections of the steam turbine set by using the modal rotating speed.

Further, in an embodiment of the present invention, the performing the transient torque identification according to the current modal rotation speed to obtain a transient torque identification value includes: converting the current modal rotating speed into a modal rotating speed signal of a shafting position corresponding to the torque; integrating modal rotating speed signals of a shafting position corresponding to the torque to obtain torsion angles corresponding to the modes; converting the torsion angles corresponding to the modes into electric torsion angles of the mass relative to a synchronous rotation coordinate system; and solving the torque between the shaft sections according to the electric torsion angle of the mass relative to the synchronous rotating coordinate system.

Specifically, a transient torque identification link

The transient torque identification link mainly has the advantages that the shafting transient torque of the unit is calculated by utilizing the modal rotating speed and the shafting parameters of the unit, the calculation steps are as follows, taking the currently obtained rotating speed signal as the rotating speed of the high-pressure cylinder as an example:

1) converting the modal rotating speed signal omega at the high-pressure cylinder into a modal rotating speed signal omega of a shafting position corresponding to the torque^(m)Namely:

ω^(m)ω/k (/ is defined as the division of the corresponding elements of the matrix),

ω＝[ω₁ ω₂ … ω_n-1 0],ω^(m)＝[ω₁ ^(m) ω₂ ^(m) … ω_n-1 ^(m) 0]，

wherein the coefficient row vector K is determined by the rotational inertia M of the shafting of the unit and the elastic coefficient K;

2) to, forω^(m)Integral solution is carried out to obtain the torsion angle delta corresponding to each mode^(m)；

3) The torsion angle delta corresponding to each mode^(m)The transformation is the electrical torsion angle delta of the mass relative to the synchronous rotating coordinate system, namely:

[δ₁ δ₂ … δ_n-1 δ_n]^T＝Q·[δ₁ ^(m) δ₂ ^(m) … δ_n-1 ^(m) 0]^T，

the coefficient matrix Q is determined by the rotational inertia M of a unit shafting and an elastic coefficient K;

4) solving the torque T between the shaft sections_ijNamely:

T_ij＝K_ij(δ_i-δ_j)，

wherein, K_ijRepresenting the spring constant between the shaft segments.

Through the steps, the transient torque of the steam turbine set can be solved by using the rotating speed of the shafting.

In step S203, if the current mode rotation speed is greater than the first preset value, it is determined whether the transient torque identification value is greater than the second preset value.

It can be understood that after the starting logic is met, the protection criterion is started to collect the current voltage, current and rotating speed of the unit. Specifically, the method comprises the following steps: step S203 is a start logic as shown in fig. 1: and judging whether the modal rotating speed exceeds a first preset value, if so, sending a starting signal, judging whether the transient torque identification value is larger than a second preset value and is in a continuous increase state, and collecting the current voltage, current and rotating speed of the unit.

Specifically, a logical link is initiated

When the modal rotating speed of the unit is lower than a certain value, the torque between the blocks of the unit shafting is small, and the risk of overlarge fatigue loss or damage does not exist in the unit shafting. In order to reduce the calculation amount of the protection device, a first preset value can be set in the protection device, and the protection device can send out a starting signal only when the module mode rotating speed of the unit is higher than the first preset value, otherwise, the protection device does not send out the starting signal. Only when the starting signal exists, the protection device can judge whether the transient torque identification value is larger than a second preset value and is in a continuous increasing state, and the current voltage, current and rotating speed of the unit are collected.

In step S204, if the transient torque identification value is greater than the second preset value and is in a continuously increasing state, a trip command is issued to cut off the current unit.

It can be understood that after the starting signal is detected, the protection device starts to acquire the current voltage, current and rotating speed of the unit and carries out protection criterion, and when the criterion is met, the protection device sends a tripping command; and when the criterion is not met, the protection device does not act.

Further, in an embodiment of the present invention, if the transient torque identification value is greater than the second preset value and is in a continuously increasing state, the issuing of the trip command includes: judging whether the transient torque identification value is larger than a second preset value or not; if the current cycle torque peak value is larger than the second preset value, delaying one cycle to judge whether the current cycle torque peak value is in a continuous increase state or not according to the current cycle torque peak value and the previous cycle torque peak value; if the status is continuously increasing, a trip instruction is generated.

Specifically, as shown in fig. 1, the protection criterion links

After the start logic sends out a start signal, the protection device starts to perform protection criterion. And when the transient torque identification value of the unit is in a second preset value and is in a continuous increasing state, judging that the transient torque identification value meets the protection criterion, and sending a tripping command. The concrete implementation method of the criterion is as follows:

firstly, comparing the transient torque identification value with a second preset value, and judging that the transient torque is out of limit if the identification value is greater than the second preset value; then, delaying a cycle, comparing the current cycle torque peak value with the previous cycle torque peak value, and judging whether the transient torque is in a continuous increase state.

Only when the two are satisfied simultaneously, the protection device can send a tripping command to disconnect the unit from the power grid, so that the shafting of the unit is prevented from being damaged more greatly.

To sum up, the embodiment of the invention firstly utilizes the filter to filter the rotating speed signal of the shafting of the unit to obtain the modal rotating speed of the unit; then, transient torque identification and starting logic judgment are carried out; and finally, judging whether the unit shafting has the risk of damage or overlarge fatigue life loss by comparing the transient torque identification value with a second preset value. If the transient torque identification value exceeds the second preset value and is in a continuous increase state, the protection device can send a tripping command to rapidly cut off the unit, and the unit is prevented from being damaged greatly due to overlarge torque.

According to the transient torque protection method based on the shafting rotating speed for the steam turbine set, which is provided by the embodiment of the invention, the modal rotating speed acquisition and the transient torque identification are based. Firstly, filtering the rotating speed of a shafting of the unit by using a filter to obtain the modal rotating speed of the unit; then, a transient torque of the unit is obtained by utilizing a torque identification link; and finally, judging whether a tripping instruction is sent out or not by utilizing a protection criterion to disconnect the unit from the power grid, thereby avoiding the damage of the unit shafting caused by overlarge torque, ensuring the safety of the turboset shafting and effectively solving the SSR problem between the turboset and the series capacitance compensation power transmission network.

The transient torque protection device of the steam turbine set based on the rotating speed of the shafting is described next with reference to the attached drawings.

FIG. 4 shows an embodiment of the transient torque protection device for a steam turbine set based on the rotational speed of the shafting

As shown in fig. 4, the transient torque protection device 10 for a steam turbine set based on the rotational speed of the shafting includes: a modal rotational speed acquisition module 100, a transient torque identification module 200, a startup logic module 300, and a protection criteria module 400.

The modal rotating speed obtaining module 100 is configured to filter a set shafting rotating speed signal by using a filter to obtain a current modal rotating speed of the set; the transient torque identification module 200 is configured to perform transient torque identification by using the current modal rotation speed to obtain a transient torque identification value; the starting logic module 300 is configured to determine whether the transient torque identification value is greater than a second preset value when the current modal rotation speed is greater than a first preset value; the protection criterion module 400 is configured to issue a trip command to cut off the current unit when the transient torque identification value is greater than the second preset value and is in a continuously increasing state. The device 10 of the embodiment of the invention can avoid damage to the shafting of the turbine generator set due to overlarge torque, ensure the safety of the shafting of the turbine generator set and effectively solve the SSR problem between the turbine generator set and the series capacitance compensation power transmission network.

Further, in an embodiment of the present invention, the protection criterion module 400 is further configured to determine whether the transient torque identification value is greater than a second preset value; if the current cycle torque peak value is larger than the second preset value, delaying one cycle to judge whether the current cycle torque peak value is in a continuous increase state or not according to the current cycle torque peak value and the previous cycle torque peak value; if the status is continuously increasing, a trip instruction is generated.

Further, in an embodiment of the present invention, the transient torque identification module 200 is further configured to convert the current modal rotation speed into a modal rotation speed signal of the shafting position corresponding to the torque; integrating modal rotating speed signals of a shafting position corresponding to the torque to obtain torsion angles corresponding to the modes; converting the torsion angles corresponding to the modes into electric torsion angles of the mass relative to a synchronous rotation coordinate system; and solving the torque between the shaft sections according to the electric torsion angle of the mass relative to the synchronous rotating coordinate system.

Further, in one embodiment of the present invention, the conversion formula of the modal rotation speed signal is:

ω^(m)＝ω./k，

wherein, omega is the current mode rotating speed,/is defined as the division of the corresponding elements of the matrix, and k is the coefficient row vector;

for omega^(m)Integrating to obtain the torsion angle delta corresponding to each mode^(m)；

The conversion formula of the electric torsion angle is as follows:

[δ₁ δ₂ … δ_n-1 δ_n]^T＝Q·[δ₁ ^(m) δ₂ ^(m) … δ_n-1 ^(m) 0]^T，

where Q is the coefficient matrix, δ^(m)The twist angle corresponding to each mode is δ is the electrical twist angle.

Further, in one embodiment of the present invention, the torque between the shaft segments is calculated by the formula:

T_ij＝K_ij(δ_i-δ_j)，

wherein, K_ijRepresenting the spring constant between the shaft segments.

It should be noted that the explanation of the embodiment of the method for protecting transient torque of a steam turbine set based on rotational speed of a shaft system is also applicable to the device for protecting transient torque of a steam turbine set based on rotational speed of a shaft system in the embodiment, and is not repeated herein.

The transient torque protection device for the steam turbine set based on the shafting rotating speed is based on modal rotating speed acquisition and transient torque identification. Firstly, filtering the rotating speed of a shafting of the unit by using a filter to obtain the modal rotating speed of the unit; then, a transient torque of the unit is obtained by utilizing a torque identification link; and finally, judging whether a tripping instruction is sent out or not by utilizing a protection criterion to disconnect the unit from the power grid, thereby avoiding the damage of the unit shafting caused by overlarge torque, ensuring the safety of the turboset shafting and effectively solving the SSR problem between the turboset and the series capacitance compensation power transmission network.

In addition, the method and apparatus of the embodiments of the present invention can be implemented by various methods in the specific analysis, including but not limited to:

(1) the integral structure of the protection device is changed into other forms;

(2) obtaining the modal rotating speed by adopting a filter design method different from that of the invention;

(3) using shafting rotating speed signals at other positions, such as the rotating speed of the intermediate pressure cylinder, the rotating speed of the low pressure cylinder and the like;

(4) the invention is realized by combining circuits or/and various functional modules in various analysis software;

(5) the combined application of the above implementation methods.

On the basis of the technical scheme of the invention, the improvement and equivalent transformation of the module structures in the protection device according to the principle of the invention are not excluded from the protection scope of the invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.