CN115951216A - Automatic checking method for generator grid-related protection and excitation system limiting function - Google Patents
Automatic checking method for generator grid-related protection and excitation system limiting function Download PDFInfo
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Abstract
The invention belongs to the technical field of power systems, and particularly relates to a method for automatically checking the grid-related protection of a generator and the limiting function of an excitation system. The method comprises the following steps: automatic checking of overload protection of a generator rotor and an excitation system over-excitation limiting function; automatic checking of the generator loss-of-excitation protection and excitation system low excitation limiting function; automatic checking of generator over-excitation protection and excitation system volt-hertz limit function; automatic checking of overvoltage protection of a generator stator and overvoltage limiting function of an excitation system stator; and automatically checking the overload protection of the generator stator and the overcurrent limiting function of the excitation system stator. The invention improves the risk resistance of the generator, prevents grid-related protection and limitation from being refused to operate and misoperation, ensures the safe and stable operation of the system, reduces the failure damage range, enhances the checking and management work of the grid-related protection and limitation setting value of the power plant, checks whether the action characteristics of the grid-related protection of the generator and the limitation of the excitation system are correctly matched, and provides support for the safe operation analysis and decision of the generator.
Description
Technical Field
The invention belongs to the technical field of power systems, and particularly relates to a method for automatically checking the grid-related protection of a generator and the limiting function of an excitation system.
Background
In recent years, with the construction of extra-high voltage and high voltage direct current transmission of national power grids and the development of new energy sources such as pumped storage, wind power, photovoltaic and the like, the power industry increasingly attaches importance to the related requirements of machine-grid coordination. The latest national standard and the latest industry standard both put forward corresponding specific requirements.
The state puts forward a requirement on the aspects of machine-network coordination to prevent the machine-network coordination and large-area wind power off-network accidents. The contents involved include: the system comprises a generator excitation system, a speed regulation system, a generator, transformer relay protection, low-frequency load shedding, primary frequency modulation of the generator, generator phase-advancing operation, out-of-step oscillation, generator out-of-field asynchronous operation and the like.
The excitation system is functionally provided with perfect limiting and protecting units, including over-excitation limiting, low-excitation limiting, V/Hz limiting, overvoltage protection and the like. The generator-transformer group protection is also provided with protection related to an excitation system, such as excitation winding overload, field loss protection, over-excitation protection, generator overvoltage protection and the like. Therefore, the constant value parameters of the excitation system are matched with the protection constant value of the generator-transformer set according to the abnormal operation condition of the system, the limiting function of the excitation system is fully utilized, and the safe and stable operation of the unit is guaranteed.
At present, the fixed values of the generator grid-related protection and excitation system control parameters are generally entrusted to a debugging unit and an equipment manufacturer to be set or set, and some debugging fixed values even use a capital construction department. After the generator is normally put into operation, the problems of lack of grid-related protection and limitation of the generator, coordination between an actual power grid and the like are easily caused.
Disclosure of Invention
Aiming at the defects existing in the prior art, the invention provides an automatic checking method for the power generator grid-related protection and the excitation system limiting function. The invention aims to realize automatic checking of the matching relation between the power generator grid-related protection and the limiting function of an excitation system, prevent grid-related protection and limitation from refusing action and misoperation, ensure safe and stable operation of a system, reduce the fault damage range and enhance the checking and management work of the grid-related protection and limitation setting value of a power plant.
The technical scheme adopted by the invention for realizing the purpose is as follows:
a method for automatically checking the power generator grid-related protection and the limiting function of an excitation system comprises the following steps:
automatic checking of overload protection of a generator rotor and an excitation system over-excitation limiting function;
automatic checking of the generator loss-of-excitation protection and excitation system low excitation limiting function;
automatic checking of generator over-excitation protection and excitation system volt-hertz limit function;
automatic checking of overvoltage protection of a generator stator and overvoltage limiting function of an excitation system stator;
and automatically checking the overload protection of the generator stator and the overcurrent limiting function of the excitation system stator.
Furthermore, the automatic checking of the generator rotor overload protection and excitation system excitation limiting function comprises the following steps: the excitation system over-excitation limiting function needs an inverse time limit characteristic matched with the over-load protection of the generator rotor, and is a precondition for limiting excitation current during strong excitation time, the over-load protection fixed value of the generator rotor is greater than the action fixed value of the over-excitation limiter, the corresponding value of the over-load capacity of the generator rotor is greater than the protection fixed value of the rotor over-load, and the corresponding value of the over-load capacity of the generator rotor, the rotor over-load protection fixed value and the action fixed value of the over-excitation limiter are gradually decreased, so that a step difference is reserved for the over-load capacity corresponding value, the rotor over-load protection fixed value and the over-excitation limiter.
Furthermore, the generator loss-of-excitation protection and low excitation limiting function of the excitation system can be automatically checked: the excitation system low excitation limitation is prior to the principle of generator demagnetization protection action, a low excitation limitation curve is matched with a static stability limit boundary, a certain margin is reserved, the generator is subjected to demagnetization from the beginning until instability occurs at last, the power and the impedance at the end of a measuring machine enter a limited low excitation area firstly and then enter a protection low excitation area, and a demagnetization protection circle is obtained finally.
Furthermore, the generator over-excitation protection and the automatic checking of the excitation system volt-hertz limit function are as follows: the excitation system volt-hertz limitation is matched with the over-excitation characteristic of the generator, and has the characteristics of timing limit and inverse time limit, and the excitation regulation of the dynamic process of the generator is not influenced by the action of the ratio limiting unit of voltage and frequency; the inverse time limit characteristic adopts a non-functional multi-point expression mode and is matched with the timing limit and inverse time limit characteristic of the over-excitation protection.
Furthermore, the automatic checking of the overvoltage protection function of the stator of the generator and the overvoltage limitation function of the stator of the excitation system comprises the following steps: if the excitation system is provided with a stator overvoltage limiting function, the excitation system is matched with the generator stator overvoltage protection, the limiting link is required to act before the unit protection, and the stator overvoltage limitation of the excitation system is generally a fixed time limit and has the same characteristic as the generator stator overvoltage protection.
Furthermore, the automatic checking of the generator stator overload protection and excitation system stator overcurrent limiting function comprises the following steps: the stator overcurrent limiting of the excitation system is matched with the stator overload protection of the generator, the principle that the stator current limiting is prior to the stator overload protection action is followed, the stator overcurrent limiting action area is smaller than the stator overload protection action area, meanwhile, the stator overload protection action area is also smaller than the allowable overload capacity of the generator, and a proper margin is reserved.
Furthermore, automatic checking of the overload protection function and the overload limiting function of the excitation system of the generator rotor is carried out, wherein the type of an over-excitation inverse time limit characteristic function is consistent with that of a generator magnetic field overcurrent characteristic function, a level difference is reserved between an over-excitation inverse time limit and the generator rotor winding overload protection characteristic, and the over-excitation inverse time limit delay under the top current is reduced by 2s compared with the generator rotor overload protection delay;
the overexcitation inverse time limit starting value is smaller than the starting value of the generator rotor overload protection, the overexcitation inverse time limit starting value is 105% -110% of the rated field current of the generator, the starting value does not influence the inverse time limit characteristic, the forced excitation inverse time limit limiting value is reduced by 5% -10% of the rated field current of the generator compared with the starting value so as to release accumulated heat and limit the accumulated heat to the starting value, and then the field current is reduced according to a forced excitation limiting action signal;
the excitation system over-excitation limitation, generator rotor overload protection and generator rotor strong excitation capacity curve follows inverse time limit overheating characteristics:
in the formula: i is * Is the per unit value of the rotor current; a is a heat capacity constant; t is time.
Furthermore, the generator field loss protection and the automatic checking of the low excitation limiting function of the excitation system are realized, wherein an under excitation limiting action curve is determined according to different active power static stability limits of the generator and heating conditions of the end part of the generator; when a phase-entering curve is determined according to the static stability condition of the system, determining an underexcitation action curve of the system according to the equivalent impedance of the system in the minimum operation mode of the system; as active power P = P N Time allowed reactive power and Q = -0.05Q N And when P =0, Q = -0.3Q N Two points to determine the under-excitation limited action curve, where P N 、Q N Rated active power and rated reactive power respectively; when a large phase advance exists, 10% reserve coefficient is set according to a static stability limit value and does not exceed a P-Q operation curve provided by a manufacturer;
the general principle of setting the low excitation limit is as follows: reasonably defining the active output full range, meeting the thermal stability limit requirement of the end part of the stator and the static stability limit requirement, adjusting according to the voltage change of the generator end, and coordinating with the loss of excitation protection; the low excitation limiting action curve is set on a P-Q plane of the generator according to system reactive reserve determined by a phase advance test, the impedance type field loss protection is calculated on an R-X measurement impedance plane at the generator end, the low excitation limiting action curve and the impedance type field loss protection are reduced to the same coordinate plane for discussion, and when the low excitation limiting of the excitation system, the field loss protection of the generator, the phase advance test and the P-Q limit are checked, a power point is selected corresponding to an active power point set in a low excitation limiting fixed value.
Furthermore, the generator over-excitation protection and the automatic checking of the excitation system volt-hertz limiting function are realized, wherein the generator set over-excitation protection is provided with timing over-excitation protection or inverse time-limited over-excitation protection consisting of a low fixed value and a high fixed value, and the inverse time-limited over-excitation protection is preferably provided; when the generator set overexcitation protection configuration is protected by a timing limit, a low fixed value part acts on a signal, and a high fixed value part acts on disconnection; when the over-excitation protection of the generator set is configured with the inverse time limit protection, the inverse time limit protection acts on disconnection; the inverse time limit over-excitation protection starting value is 1.07 times higher than the rated value.
Furthermore, the automatic checking of the overvoltage protection function of the stator of the generator and the overvoltage limitation function of the stator of the excitation system is realized, wherein the setting value of the overvoltage protection of the stator adopts a high setting value on the premise that the overvoltage protection of the generator is not exceeded; for the hydroelectric generating set, the overvoltage protection setting value is determined according to the insulation condition of a stator winding, and is higher than 1.5 times of rated voltage according to the specification of DL/T684, and the action time limit is 0.5s; the silicon controlled rectifier is adopted for excitation, the voltage is 1.3 times higher than the rated voltage, and the action time limit is 0.3s; protection action is on the disconnection; for a steam turbine generator unit, an overvoltage protection setting value is determined according to the insulation condition of a stator winding, the overvoltage protection setting value is higher than 1.3 times of rated voltage according to the provisions of DL/T684, the action time limit is 0.5s, and protection action is performed in disconnection;
the automatic checking of the generator stator overload protection and excitation system stator overcurrent limiting functions is characterized in that the stator overcurrent limitation of an excitation system is inverse time limit characteristics, the excitation regulator action time corresponding to each stator current multiple is determined according to the excitation regulator stator overcurrent limitation and the stator overcurrent limitation fixed value or parameter setting in the excitation regulator, the overload protection time setting value corresponding to each stator current multiple is determined according to the generator protection setting value, the generator stator overload capacity represents the capacity of generator equipment passing the stator current, and the capacity curve of the generator stator overload capacity represents the allowable time corresponding to each stator current multiple.
The invention has the following beneficial effects and advantages:
the automatic checking method can improve the risk resistance of the generator, prevent grid-related protection and limitation from refusing and misoperation, ensure the safe and stable operation of the system, reduce the fault damage range, enhance the checking and management work of the grid-related protection and limitation setting value of the power plant, and check whether the action characteristics of the grid-related protection of the generator and the limitation of the excitation system are correctly matched. The automatic checking of the matching relation between the power generator grid-related protection and the excitation system limiting function is realized, and support is provided for the safe operation analysis and decision of the power generator.
Drawings
The above 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 graph of excitation system over-excitation limit and generator rotor overload protection characteristics of the present invention;
fig. 2 is a graph of the overvoltage protection and the hertz limitation characteristic of the excitation system of the generator of the invention.
Detailed Description
In order that the above objects, features and advantages of the present invention can be more clearly understood, a more particular description of the invention will be rendered by reference to the appended drawings. It should be noted that the embodiments and features of the embodiments of the present application may be combined with each other without conflict.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced in other ways than those specifically described herein, and therefore the scope of the present invention is not limited by the specific embodiments disclosed below.
The solution of some embodiments of the invention is described below with reference to fig. 1 and 2.
Example 1
The invention provides an embodiment, in particular to a method for automatically checking the power generator grid-related protection and the limiting function of an excitation system, which comprises the following steps:
automatic checking of overload protection of a generator rotor and an excitation system over-excitation limiting function;
automatic checking of the generator field loss protection and low excitation limiting function of an excitation system;
automatic checking of generator over-excitation protection and excitation system VoHz limitation function;
automatic checking of overvoltage protection of a generator stator and overvoltage limiting function of an excitation system stator;
and automatically checking the overload protection of the generator stator and the overcurrent limiting function of the excitation system stator.
The invention relates to an automatic checking method of the overload protection and excitation system overexcitation limiting function of a generator rotor, which comprises the following steps: the excitation system over-excitation limiting function needs an inverse time limit characteristic matched with the generator rotor overload protection, which is a precondition for limiting excitation current during strong excitation time, the generator rotor overload protection fixed value must be larger than the over-excitation limiter action fixed value, meanwhile, the generator rotor overload capacity corresponding value is larger than the rotor overload protection fixed value, the generator rotor overload capacity corresponding value, the rotor overload protection fixed value and the over-excitation limiter action fixed value are gradually decreased, and a certain level difference should be reserved for the three.
The invention relates to a generator loss-of-excitation protection and excitation system low excitation limiting function automatic checking method, which comprises the following steps: the excitation system low excitation limit is prior to the principle of generator demagnetization protection action, a low excitation limit curve is matched with a static stability limit boundary, a certain margin is reserved, the generator is demagnetized from the beginning until the final instability occurs, the power and the impedance at the measuring machine end are required to enter a limit low excitation area firstly and then enter a protection low excitation area, and finally a demagnetization protection circle is obtained.
The invention relates to a generator over-excitation protection and excitation system volt-hertz limiting function automatic check method, which comprises the following steps: the excitation system volt-hertz limit is matched with the over-excitation characteristic of the generator, and has the characteristics of a fixed time limit and an inverse time limit, and the excitation regulation of the dynamic process of the generator is not influenced by the action of the voltage-frequency ratio limiting unit. The inverse time limit characteristic is preferably expressed in a non-functional multi-point mode and should be matched with the timing limit and inverse time limit characteristic of the over-excitation protection.
The invention relates to an automatic checking method of overvoltage protection of a generator stator and overvoltage limiting function of an excitation system stator, which comprises the following steps: if the excitation system is provided with a stator overvoltage limiting function, the excitation system is matched with the generator stator overvoltage protection, the limiting link is required to act before the unit protection, and the stator overvoltage limitation of the excitation system is generally a fixed time limit and has the same characteristic as the generator stator overvoltage protection.
The invention relates to a method for automatically checking the overload protection of a generator stator and the overcurrent limiting function of an excitation system stator, which comprises the following steps: the stator overcurrent limiting of the excitation system is matched with the stator overload protection of the generator, the principle that the stator current limiting precedes the stator overload protection action is followed, the action area of the stator overcurrent limiting is smaller than the action area of the stator overload protection, and meanwhile, the action area of the stator overload protection is smaller than the allowable overload capacity of the generator, and a proper margin is reserved.
Example 2
The invention also provides an embodiment, which is a method for automatically checking the power generator grid-related protection and the excitation system limiting function, and the method specifically comprises the following steps:
and 1, automatically checking the overload protection of the generator rotor and the excitation system over-excitation limiting function.
The automatic checking of the over-load protection function of the generator rotor and the over-excitation limiting function of the excitation system has the advantages that the type of the over-excitation inverse time limit characteristic function is consistent with that of the over-current characteristic function of the generator magnetic field, a level difference is reserved between the over-excitation inverse time limit and the over-load protection characteristic of the generator rotor winding, the over-excitation inverse time limit delay under the top current is properly reduced than the over-load protection delay of the generator rotor, but is not too large, and can be generally 2s.
The overexcitation inverse time limit starting value is smaller than the starting value of the generator rotor overload protection, generally 105% -110% of the rated field current of the generator is achieved, the inverse time limit characteristic is not influenced by the starting value, the forced excitation inverse time limit limiting value is generally reduced by 5% -10% of the rated field current of the generator compared with the starting value so as to release accumulated heat and can be limited to the starting value, and then the field current is reduced by an operator according to a forced excitation limiting action signal.
The excitation system over-excitation limitation and generator rotor overload protection and the generator rotor strong excitation capacity curve generally follow the inverse time limit overheating characteristic:
in the formula:
I * -per unit value of rotor current;
a-heat capacity constant;
t is time.
The excitation system overexcitation limit and generator rotor overload protection characteristic curve is shown in fig. 1, a requirement a for a steam turbine generator is not less than 33.75, and a typical excitation system overexcitation limit is 30.
And 2, automatically checking the loss of excitation protection of the generator and the low excitation limiting function of an excitation system.
And the under-excitation limiting action curve is determined according to different active power static stability limits of the generator and heating conditions of the end part of the generator. When the phase-entering curve is determined according to the static stability condition of the system, the underexcitation action curve of the system is determined according to the equivalent impedance of the system in the minimum operation mode of the system. If no special phase advance requirement exists, the active power P = P can be generally set N Time allowed reactive power and Q = -0.05Q N And when P =0, Q = -0.3Q N Two points to determine the under-excitation limited action curve, where P N 、Q N Rated active power and rated reactive power respectively. When a large phase advance is required, the reserve coefficient setting can be generally kept about 10% according to the static stability limit value, but the reserve coefficient setting cannot exceed a P-Q operation curve provided by a manufacturing plant.
The general principle of setting the low excitation limit can be summarized as: the method is reasonably defined in the full range of active output, meets the limit requirement of thermal stability of the end part of the stator, meets the limit requirement of static stability, adjusts according to the change of terminal voltage, and is in coordination with the loss of excitation protection. The low excitation limiting action curve is set on a P-Q plane of the generator according to system reactive reserve determined by a phase-entering test, the impedance type field loss protection is calculated on an R-X measurement impedance plane at the generator end, in order to correctly check the matching relation between the low excitation limiting action curve and the impedance type field loss protection, the low excitation limiting action curve and the impedance type field loss protection must be reduced to the same coordinate plane for discussion, and when the low excitation limiting action curve, the field loss protection curve, the phase-entering test and the P-Q limit of the excitation system are checked, a power point can be selected according to an active power point set in a low excitation limiting fixed value.
And 3, automatically checking the over-excitation protection and the volt-hertz limit function of the excitation system of the generator.
The generator over-excitation protection and the automatic checking of the excitation system VoHz limitation function are characterized in that the generator set over-excitation protection is provided with timing over-excitation protection or inverse time-limited over-excitation protection consisting of a low fixed value part and a high fixed value part, and preferably the inverse time-limited over-excitation protection is preferentially provided. When the generator set overexcitation protection configuration is time limit protection, the low fixed value part of the generator set overexcitation protection configuration should act on a signal, and the high fixed value part of the generator set overexcitation protection configuration should act on disconnection. When the over-excitation protection of the generator set is configured with the inverse time limit protection, the inverse time limit protection should act on disconnection. The inverse time limit over-excitation protection starting value is 1.07 times higher than the rated value.
The generator over-excitation protection and excitation system Hertz limit characteristic curve is shown in figure 2.
And 4, automatically checking the overvoltage protection function of the generator stator and the overvoltage limiting function of the excitation system stator.
The automatic checking of the overvoltage protection function of the stator of the generator and the overvoltage limitation function of the stator of the excitation system ensures that the setting value of the overvoltage protection of the stator adopts a higher setting value on the premise of not exceeding the overvoltage capacity of the generator. For the hydroelectric generating set, the overvoltage protection setting value is determined according to the insulation condition of a stator winding, is higher than 1.5 times of rated voltage according to the specification of DL/T684, and the action time limit is 0.5s; the silicon controlled rectifier is adopted for excitation, the voltage is 1.3 times higher than the rated voltage, and the action time limit is 0.3s. The protection acts on the split. For the steam turbine generator unit, the overvoltage protection setting value is determined according to the insulation condition of the stator winding, is higher than 1.3 times of rated voltage according to the specification of DL/T684, the action time limit is 0.5s, and the protection action is performed in disconnection.
And 5, automatically checking the overload protection function of the generator stator and the over-current limiting function of the excitation system stator.
The automatic checking of the generator stator overload protection and excitation system stator overcurrent limiting function is characterized in that the stator overcurrent limitation of an excitation system is generally inverse time-lag characteristic, the excitation regulator action time corresponding to each stator current multiple can be determined according to the excitation regulator stator overcurrent limitation and the stator overcurrent limitation fixed value or parameter setting in the excitation regulator, the overload protection time setting value corresponding to each stator current multiple is determined according to the generator protection setting value, the generator stator overload capacity represents the capacity of a generator device passing through the stator current, and the capacity curve of the generator stator overload capacity represents the allowable time corresponding to each stator current multiple.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting the same, and although the present invention is described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications and equivalents may be made to the embodiments of the invention without departing from the spirit and scope of the invention, which is to be covered by the claims.
Claims (10)
1. A method for automatically checking the power generator grid-related protection and the limiting function of an excitation system is characterized by comprising the following steps: the method comprises the following steps:
automatic checking of overload protection of a generator rotor and an excitation system over-excitation limiting function;
automatic checking of the generator field loss protection and low excitation limiting function of an excitation system;
automatic checking of generator over-excitation protection and excitation system volt-hertz limit function;
automatic checking of overvoltage protection of a generator stator and overvoltage limiting function of an excitation system stator;
and automatically checking the overload protection of the generator stator and the overcurrent limiting function of the excitation system stator.
2. The method for automatically checking the power generator grid-related protection and excitation system limiting function according to claim 1, is characterized in that: the automatic checking of the overload protection of the generator rotor and the excitation limiting function of the excitation system comprises the following steps: the excitation system over-excitation limiting function needs inverse time limit characteristics matched with over-load protection of a generator rotor, and is a precondition for limiting excitation current during strong excitation time, an over-load protection fixed value of the generator rotor is larger than an action fixed value of an over-excitation limiter, meanwhile, an over-load capacity corresponding value of the generator rotor is larger than a protection fixed value of the rotor over-load, and the over-load capacity corresponding value of the generator rotor, the over-load protection fixed value of the rotor and the action fixed value of the over-excitation limiter are gradually decreased, so that a level difference is reserved for the over-load capacity corresponding value, the over-load protection fixed value of the rotor and the action fixed value of the over-excitation limiter.
3. The method for automatically checking the power generator grid-related protection and excitation system limiting function according to claim 1, is characterized in that: the automatic checking of the generator field loss protection and excitation system low excitation limiting function comprises the following steps: the excitation system low excitation limit is prior to the principle of generator demagnetization protection action, a low excitation limit curve is matched with a static stability limit boundary, a certain margin is reserved, the generator is demagnetized from the beginning until the final instability occurs, the power and the impedance at the measuring machine end are required to enter a limit low excitation area firstly and then enter a protection low excitation area, and finally a demagnetization protection circle is obtained.
4. The method for automatically checking the power generator grid-related protection and excitation system limiting function according to claim 1, is characterized in that: the automatic checking of the over-excitation protection and the Hertz limit function of the excitation system of the generator comprises the following steps: the excitation system volt-hertz limit is matched with the over-excitation characteristic of the generator, and has the characteristics of a fixed time limit and an inverse time limit, and the excitation regulation of the dynamic process of the generator is not influenced by the action of the voltage-frequency ratio limiting unit; the inverse time limit characteristic adopts a non-functional multi-point expression mode and is matched with the timing limit and inverse time limit characteristic of the over-excitation protection.
5. The method for automatically checking the power generator grid-related protection and excitation system limiting function according to claim 1, is characterized in that: the automatic checking of the overvoltage protection function of the generator stator and the overvoltage limiting function of the excitation system stator comprises the following steps: if the excitation system is provided with a stator overvoltage limiting function, the excitation system is matched with the generator stator overvoltage protection, the limiting link is required to act before the unit protection, and the stator overvoltage limitation of the excitation system is generally a fixed time limit and has the same characteristic as the generator stator overvoltage protection.
6. The method for automatically checking the power generator grid-related protection and excitation system limiting function according to claim 1, is characterized in that: the automatic checking of the generator stator overload protection and excitation system stator overcurrent limiting function comprises the following steps: the stator overcurrent limiting of the excitation system is matched with the stator overload protection of the generator, the principle that the stator current limiting is prior to the stator overload protection action is followed, the stator overcurrent limiting action area is smaller than the stator overload protection action area, meanwhile, the stator overload protection action area is also smaller than the allowable overload capacity of the generator, and a proper margin is reserved.
7. The method for automatically checking the power generator grid-related protection and excitation system limiting function according to claim 1, is characterized in that: the automatic checking of the overload protection function of the generator rotor and the overload limiting function of an excitation system is carried out, wherein the type of an over-excitation inverse time limit characteristic function is consistent with that of a generator magnetic field overcurrent characteristic function, a level difference is reserved between an over-excitation inverse time limit and the generator rotor winding overload protection characteristic, the over-excitation inverse time limit delay under the top current is reduced by 2s compared with the generator rotor overload protection delay;
the overexcitation inverse time limit starting value is smaller than the starting value of the generator rotor overload protection, the overexcitation inverse time limit starting value is 105% -110% of the rated field current of the generator, the starting value does not influence the inverse time limit characteristic, the forced excitation inverse time limit limiting value is reduced by 5% -10% of the rated field current of the generator compared with the starting value so as to release accumulated heat and limit the accumulated heat to the starting value, and then the field current is reduced according to a forced excitation limiting action signal;
the excitation system over-excitation limitation, generator rotor overload protection and generator rotor strong excitation capacity curve follows inverse time limit overheating characteristics:
in the formula: i is * Is the per unit value of the rotor current; a is a heat capacity constant; t is time.
8. The method for automatically checking the power generator grid-related protection and excitation system limiting function according to claim 1, is characterized in that: the generator magnetic loss protection and the automatic checking of the low excitation limiting function of the excitation system are realized, wherein the low excitation limiting action curve is determined according to different active power static stability limits of the generator and heating conditions of the end part of the generator; when a phase-entering curve is determined according to the static stability condition of a system, determining an underexcitation action curve of the system according to the equivalent impedance of the system in the minimum operation mode of the system; as active power P = P N Time allowed reactive power and Q = -0.05Q N And when P =0, Q = -0.3Q N Two points to determine the under-excitation-limited action curve, where P N 、Q N Rated active power and rated reactive power respectively; when a large phase advance exists, 10% reserve coefficient setting is reserved according to a static stability limit value, and a P-Q operation curve provided by a manufacturer is not exceeded;
the general principle for setting the low excitation limit is as follows: reasonably defining the active output full range, meeting the thermal stability limit requirement of the end part of the stator and the static stability limit requirement, adjusting according to the voltage change of the generator end, and coordinating with the loss of excitation protection; the low excitation limiting action curve is set on a P-Q plane of the generator according to system reactive reserve determined by a phase advance test, the impedance type field loss protection is calculated on an R-X measurement impedance plane at the generator end, the low excitation limiting action curve and the impedance type field loss protection are reduced to the same coordinate plane for discussion, and when the low excitation limiting of the excitation system, the field loss protection of the generator, the phase advance test and the P-Q limit are checked, a power point is selected corresponding to an active power point set in a low excitation limiting fixed value.
9. The method for automatically checking the power generator grid-related protection and excitation system limiting function according to claim 1, is characterized in that: the generator over-excitation protection and the automatic check of the excitation system Vocal Hertz limit function are realized, wherein the generator set over-excitation protection is provided with timing over-excitation protection or inverse time limit over-excitation protection consisting of a low fixed value part and a high fixed value part, and the inverse time limit over-excitation protection is preferably provided; when the generator set overexcitation protection configuration is time-limited protection, the low fixed value part acts on a signal, and the high fixed value part acts on disconnection; when the over-excitation protection of the generator set is configured with the inverse time limit protection, the inverse time limit protection acts on disconnection; the starting value of the inverse time limit over-excitation protection is 1.07 times higher than the rated value.
10. The method for automatically checking the power generator grid-related protection and excitation system limiting function according to claim 1, is characterized in that: the automatic checking of the overvoltage protection function of the stator of the generator and the overvoltage limiting function of the stator of the excitation system is carried out, wherein a high fixed value is adopted on the premise that the setting value of the overvoltage protection of the stator does not exceed the overvoltage capacity of the generator; for the hydroelectric generating set, the overvoltage protection setting value is determined according to the insulation condition of a stator winding, and is higher than 1.5 times of rated voltage according to the specification of DL/T684, and the action time limit is 0.5s; the silicon controlled rectifier is adopted for excitation, the voltage is 1.3 times higher than the rated voltage, and the action time limit is 0.3s; protection action is on the disconnection; for a steam turbine generator unit, an overvoltage protection setting value is determined according to the insulation condition of a stator winding, the overvoltage protection setting value is higher than 1.3 times of rated voltage according to the specification of DL/T684, the action time limit is 0.5s, and protection action is performed in disconnection;
the automatic checking of the generator stator overload protection and excitation system stator overcurrent limiting functions is characterized in that the stator overcurrent limitation of an excitation system is inverse time limit characteristics, the excitation regulator action time corresponding to each stator current multiple is determined according to the excitation regulator stator overcurrent limitation and the stator overcurrent limitation fixed value or parameter setting in the excitation regulator, the overload protection time setting value corresponding to each stator current multiple is determined according to the generator protection setting value, the generator stator overload capacity represents the capacity of generator equipment passing the stator current, and the capacity curve of the generator stator overload capacity represents the allowable time corresponding to each stator current multiple.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202211659947.4A CN115951216A (en) | 2022-12-23 | 2022-12-23 | Automatic checking method for generator grid-related protection and excitation system limiting function |
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| CN202211659947.4A CN115951216A (en) | 2022-12-23 | 2022-12-23 | Automatic checking method for generator grid-related protection and excitation system limiting function |
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