JP2008199848A - Excitation controller of synchronous power generator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an excitation controller of a synchronous power generator for always and properly setting a low excitation limit in response to a change in a phase advance operation allowed region, and expanding a reactive power adjustment range on the phase advance side in comparison with a conventional apparatus. <P>SOLUTION: The excitation controller 4 is provided with a MEL function section 44, and an AVR 45. The MEL function section 44 does not uniquely set the low excitation limit, discriminates the phase advance operation allowed region in response to conditions such as a power system state and an operation state of the synchronous power generator 1, and sets the low excitation limit (MEL curve) for limiting a low excitation operation range of the synchronous power generator 1 so as to reflect it. The AVR 45 limits an excitation current supplied to an excitation winding 2 of the synchronous power generator 1, and automatically adjusts its output voltage so as to prevent the low excitation limit (the MEL curve) set by the MEL function section 44 from being exceeded. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an excitation control device for a synchronous generator, and more particularly to a technique for setting a low excitation limit value (hereinafter referred to as MEL) provided for an automatic voltage regulator (hereinafter referred to as AVR).

  Generally, in a synchronous generator, turbine output (active power) is controlled by adjusting the opening degree of a guide vane by a governor (governor). Further, the output voltage of the synchronous generator is adjusted by adjusting the field current supplied to the field winding of the rotor of the synchronous generator by AVR.

  In such a synchronous generator, in the PQ characteristic diagram showing the relationship between the active power P and the reactive power Q in FIG. 27, the field winding, the stator winding, the core, etc. constituting the synchronous generator An output possible limit curve L1 based on the temperature limit of each part is defined, and it is necessary to operate within the range of this output possible limit curve L1 in order to operate the synchronous generator safely without failure.

  In addition, in order to maintain stable operation without causing inconvenience such as the output of the synchronous generator becoming unstable and stepping out of the power system, it is determined by factors such as the impedance of the power system and the synchronous generator. It is necessary not to exceed the steady state stability limit curve L2. In this figure, the steady-state stability limit curve L2 is located outside the region surrounded by the output possible limit curve L1, but is surrounded by the output possible limit curve L1 depending on the operating power system state. May go inside the area.

  Further, when the output voltage of the synchronous generator is extremely lowered, the protective relay operation curve L3 is set so that the protective relay operates to trip the synchronous generator from the power system and cut off the power supply to the system. .

  If the output of the synchronous generator deviates from the output possible limit curve L1 as described above, it will cause a failure, and if the reactive power of the synchronous generator falls below the steady-state stability limit curve L2, it will step out of the power system. Then, the synchronous operation cannot be performed, and further, when the protective relay operating curve L3 or less is reached, the protective relay operates to trip the synchronous generator from the system and cut off the power supply to the system.

  Therefore, in order to prevent such a situation from occurring, a low excitation limit curve (hereinafter referred to as “safety operation”) is considered so that the reactive power is not excessively reduced by limiting the excitation current supplied to the excitation winding of the synchronous generator in advance. L0) (referred to as MEL curve).

  In setting the MEL curve L0, if the power system is switched or the load fluctuates during the actual operation of the synchronous generator, the output possible limit curve L1 and the steady state stability limit curve L2 are accompanied accordingly. Therefore, in consideration of driving under adverse conditions, the MEL curve L0 is always located above the curves L1 to L3 (on the side where the reactive power is small) on the phase advance side. It is set with a certain margin. Conventionally, once this MEL curve L0 is set, it is maintained at a fixed value without being affected by fluctuations in the operating power system state. That is, conventionally, the MEL curve L0 is uniquely set with a certain margin with respect to the output possible limit curve L1 and the steady state stability limit curve L2.

  During operation of the synchronous generator, the active power Pe is determined by the turbine output of the synchronous generator, and the reactive power is determined by the operable range determined by the output limit curve L1 and the MEL curve L0 according to the turbine output. The adjustment range Qe-Qe ′ is determined, and the reactive power is adjusted within the adjustment range Qe-Qe ′.

  That is, the output voltage of the synchronous generator is controlled by adjusting the field current of the synchronous generator with AVR, and the reactive power corresponding to the active power is always within the adjustment range Qe-Qe ′ due to the armature reaction. The reactive power of the synchronous generator is adjusted so as to be settled. In particular, when the reactive power of the synchronous generator during load operation decreases (that is, shifts to the phase advance operation side) and reaches the MEL curve L0, the field of the synchronous generator is set so that the reactive power does not fall below the MEL curve L0. The magnetic current is increased to prevent the synchronous generator from failing.

  In the prior art, when a system fault occurs, the second preset value along the output possible limit curve L1 from the preset first MEL curve along the steady-state stability limit curve L2. A technique has also been proposed in which a failure of a synchronous generator is prevented by switching to the MEL curve (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 2-7900

  By the way, as described above, the MEL curve L0 is always positioned above the curves L1 to L3 (on the side where the reactive power is small) on the phase advance side in consideration of operation under adverse conditions. The MEL curve L0 is set with a sufficient margin, and once set, the MEL curve L0 has a fixed value without being affected by fluctuations in the power system state during operation. For this reason, in the conventional technology, there is a problem that the reactive power adjustment range on the phase advance side is narrowed, and as a result, it becomes difficult to maintain the voltage of the system.

  Further, when the phase advanceable operation region becomes narrower than the design value due to a change in the power system state or a decrease in the cooling gas pressure of the synchronous generator, for example, even if the MEL curve L0 is set in advance, the output When the region on the phase advance operation side of the possible limit curve L1 becomes narrow due to a decrease in cooling gas pressure or the like, if the MEL curve L0 is uniquely set as in the prior art, the low excitation state cannot be restricted correctly. There is.

  Furthermore, the prior art described in Patent Document 1 is a method for coping with a system fault. In normal operation in which no system fault has occurred, a low excitation limit is set under a MEL curve that is uniquely set in advance. As a result, the reactive power adjustment range on the phase advance side is still narrow, and the low excitation state cannot be correctly restricted if the phase advanceable operating range is narrower than the design value. The point is the same.

  The present invention has been made to solve the above-described problems, and does not uniquely set the MEL as in the prior art, but proceeds according to conditions such as the power system state and the operating state of the synchronous generator. The phase operation possible region is automatically determined, and the MEL is always set appropriately according to the change in the phase advance operation possible region, so that the occurrence of a failure of the synchronous generator is surely avoided and the phase advance side It is an object of the present invention to provide an excitation control device for a synchronous generator capable of expanding the adjustment range of reactive power in the conventional type.

  The excitation control device for a synchronous generator according to the present invention includes a stability limit calculation means for calculating a value of a steady state stability limit or a dynamic stability limit based on an output voltage of the synchronous generator and an impedance value of a power system, Based on the value of the steady-state stability limit or dynamic stability limit calculated by the stability limit calculation means, a low excitation limit value that limits the low excitation operation range of the synchronous generator reflecting this value is set. Adjust the output voltage by limiting the excitation current supplied to the excitation winding of the synchronous generator so that it does not exceed the low excitation limit value setting means and the low excitation limit value set by this low excitation limit value setting means And an automatic voltage adjusting means.

  According to the present invention, the MEL is not uniquely set as in the prior art, but the phase-advanceable region is automatically determined according to conditions such as the power system state and the operation state of the synchronous generator, MEL is set according to the change in the phase advanceable region. That is, since the MEL is dynamically set according to conditions such as the power system state and the synchronous generator operating state, it is not necessary to secure an excessive margin when setting the MEL, and the MEL can always be set appropriately. it can. As a result, the reactive power adjustment range on the phase advance side can be expanded more than before while reliably avoiding the failure of the synchronous generator.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram showing a power generation system including an excitation control device for a synchronous generator according to Embodiment 1 of the present invention.

  In the first embodiment, 1 is a synchronous generator, 2 is a field winding of the synchronous generator 1, and 3 is an exciter including an element such as a thyristor for supplying a field current to the field winding 2. Reference numeral 4 denotes an excitation control device that controls the excitation current output from the exciter 3. Reference numeral 5 denotes a voltage detector (PT) that detects an output voltage (terminal voltage) to the power system of the synchronous generator 1, and 6 denotes a current that detects an output current (terminal current) to the power system of the synchronous generator 1. It is a detector (CT).

  The excitation control device 4 includes a voltage setting unit 41, a difference unit 42, a power calculation unit 43, a MEL function unit 44, and an AVR 45.

  Here, the voltage setting unit 41 sets a reference voltage as a control target, and the difference unit 42 is detected by the reference voltage set by the voltage setting unit 41 and the voltage detector (PT) 5. A voltage deviation ΔV from the output voltage is output. The power calculation unit 43 calculates active power and reactive power based on both detection outputs of the voltage detector 5 and the current detector 6, respectively.

  The MEL function unit 44 calculates the steady-state stability limit curve L2 based on the output voltage Vg detected by the voltage detector 5 and the value of the current impedance Xe of the power system, and the calculated steady-state stability. Based on the limit curve L2 and the values of the active power Pg and the reactive power Qg calculated by the power calculation unit 43, the MEL curve L0 that limits the low excitation operation range of the synchronous generator 1 is set. Further, when the reactive power Qg shifts to the phase advance side and reaches the MEL curve L0, the MEL function unit 44 outputs a low excitation limit signal to the AVR 45 so as not to exceed the MEL curve L0. The MEL function unit 44 corresponds to the stability limit calculation means and the low excitation limit value setting means in the claims.

  The AVR 45 controls the exciter 3 on the basis of the voltage deviation ΔV output from the differentiator 42 within the normal operable range, thereby adjusting the field current supplied to the field winding 2 of the synchronous generator 1. By adjusting the output voltage, when the low excitation limit signal is output from the MEL function unit 4, the low excitation limit signal is fetched in preference to the output from the deviation unit 42, and this low excitation limit is set. Based on the signal, the exciter 3 is controlled so as not to exceed the MEL curve L0 and the output voltage of the synchronous generator 1 is adjusted.

  Next, the operation of the excitation control apparatus having the above configuration will be described with reference to the flowchart shown in FIG. 2 and the explanatory diagram of FIG.

  The output voltage Vg detected by the voltage detector (PT) 5 is supplied to the differentiator 42, the power calculation unit 43, and the MEL function unit 44, respectively. The output current detected by the current detector (CT) 6 is given to the power calculation unit 43.

  The difference unit 42 outputs a voltage deviation ΔV between the reference voltage set by the voltage setting unit 41 and the output voltage Vg detected by the voltage detector (PT) 5. The value of the voltage deviation ΔV is given to the AVR 45. The power calculation unit 43 calculates active power Pg and reactive power Qg based on both detection outputs of the voltage detector 5 and the current detector 6 (step A1). The values of the active power Pg and the reactive power Qg are given to the MEL function unit 44. Furthermore, the current impedance Xe value of the power system measured by an external device (not shown) is input to the MEL function unit 44 (step A2).

  The MEL function unit 44 calculates the steady-state stability limit curve L2 shown in FIG. 3 based on the values of the output voltage Vg and impedance Xe detected by the voltage detector 5 (step A3).

Next, the MEL function unit 44 calculates the phase advanceable operation point in the no-load (active power = 0) P ₀ and the rated active power P ₁ . That is, in the first embodiment, the no load (active power = 0) P ₀ and the rated active power P ₁ are considered in consideration of the output possible limit curve L1, the steady state stability limit curve L2, and the protection relay operation curve L3. The value of each reactive power on the corresponding steady state stability limit curve L2 is calculated | required, and these values are made into a phase advance operation possible point (step A4). Then, two points Q ₀ and Q ₁ including a certain margin are selected for each of these phase advanceable points, and a MEL curve L0 connecting both points Q ₀ and Q ₁ with a straight line is set (step) A5).

  Thus, when the MEL function unit 44 sets the MEL curve L0, subsequently, the reactive power Qg corresponding to the current active power Pg based on the values of the active power Pg and the reactive power Qg calculated by the power calculation unit 43. Is compared with the MEL curve L0, and if the current reactive power Qg value exceeds the MEL curve L0, a low excitation limit signal is output to the AVR 45.

  The AVR 45 controls the exciter 3 on the basis of the voltage deviation ΔV output from the differentiator 42 within the normal operable range, thereby adjusting the field current supplied to the field winding 2 of the synchronous generator 1. Thus, the output voltage is adjusted, but when the low excitation limit signal is output from the MEL function unit 4, the low excitation limit signal is preferentially taken in over the output from the differentiator 42. The exciter 3 is controlled based on the low excitation limit signal to adjust the output voltage of the synchronous generator 1. That is, the excitation current supplied from the exciter 3 to the excitation winding 2 of the synchronous generator 1 is increased by the control of the AVR 45, and the output voltage rises. The reactive power of the synchronous generator 1 is adjusted so as not to exceed the MEL curve L0 by the armature reaction accompanying this.

  As described above, in the first embodiment, the MEL curve L0 is not uniquely set as in the prior art, but the steady-state stability limit curve L2 is sequentially generated by inputting the current impedance Xe of the power system. Since the MEL curve L0 that is calculated and reflects the calculated steady state stability limit curve L2 is dynamically set, it is not necessary to secure an excessive margin as in the prior art when setting the MEL curve L0. Therefore, the reactive power adjustment range on the phase advance side can be expanded more than before while reliably avoiding the failure of the synchronous generator 1.

  In the first embodiment, the excitation control device 4 is configured by hardware by each functional block. However, the present invention is not limited to this, and may be configured by software. The same applies to the following embodiments.

Embodiment 2. FIG.
FIG. 4 is a flowchart showing the setting operation of the low excitation limit value in the excitation control apparatus of the synchronous generator according to the second embodiment, and FIG. 5 is an explanatory diagram for setting the low excitation limit value in the second embodiment. .

  In the first embodiment, the current impedance Xe value of the power system measured by an external device (not shown) is input to the MEL function unit 44 (see step A2 in FIG. 2). If the impedance changes depending on the power system pattern, each impedance corresponding to a plurality of power system patterns is set in advance in the MEL function unit 44, and the impedance corresponding to this is set by switching the power system pattern. Is possible.

  Therefore, in the second embodiment, a plurality of power system patterns and respective impedances Xe corresponding to these power system patterns are set and registered in the MEL function unit 44 in advance. For example, impedance values corresponding to the daytime pattern and nighttime pattern of the power system are set. Furthermore, in the MEL function unit 44, each steady state stability limit curve L2 corresponding to each impedance value is set and registered in advance.

  Then, when one of the power system patterns is selected (B2), the MEL function unit 44 determines an impedance corresponding to the selected power system pattern (B3), and subsequently corresponds to this impedance. The steady state stability limit curve L2 is selected (B4). Thereafter, the MEL curve L0 is set in the same manner as in the first embodiment.

As described above, in the second embodiment, each impedance Xe and the steady state stability limit curve L2 can be set in advance corresponding to the power system pattern, so that the MEL curve is compared with the first embodiment. There is an advantage that the arithmetic processing when setting L0 can be simplified.
Since other configurations and operations are the same as those in the first embodiment, detailed description thereof is omitted here.

Embodiment 3 FIG.
FIG. 6 is a block diagram showing a power generation system including an excitation control device for a synchronous generator according to a third embodiment of the present invention, and FIG. 7 shows an operation for setting a low excitation limit value in the excitation control device according to the third embodiment. A flowchart and FIG. 8 are explanatory diagrams when the low excitation limit value is set in the third embodiment.

In the first embodiment, the current impedance Xe value of the power system measured by an external device (not shown) is input to the MEL function unit 44 (see step A2 in FIG. 2). From the change ΔVg of the output voltage Vg of the synchronous generator 1 and the accompanying change ΔQg of the reactive power Qg, the impedance Xe of the power system can be calculated by the following equation.
Xe = ΔVg / ΔQg (1)
(Here Δ indicates the amount of change)

  Therefore, in the third embodiment, each value of the output voltage Vg of the synchronous generator 1 detected by the voltage detector 5 and the reactive power Qg calculated by the power calculator 43 is taken in, and the change ΔVg of the output voltage Vg is taken. And an impedance calculation unit 46 for calculating the impedance Xe of the power system by the above equation (1) from the change ΔQg of the reactive power Qg associated therewith. The impedance Xe obtained by the impedance calculation unit 46 is provided to the MEL function unit 44 (see step C2 in FIG. 7).

As described above, in the third embodiment, the current impedance Xe inside the excitation control device 4 without inputting the value of the impedance Xe of the power system measured by an external device (not shown) into the MEL function unit 44. Therefore, there is an advantage that it is possible to save labor and labor such as providing an external measuring device or performing external wiring.
Since other configurations and operations are the same as those in the first embodiment, detailed description thereof is omitted here.

Embodiment 4 FIG.
FIG. 9 is a flowchart showing the setting operation of the low excitation limit value in the excitation control apparatus of the fourth embodiment, and FIG. 10 is an explanatory diagram for setting the low excitation limit value in the fourth embodiment.

In Embodiments 1 to 3 above embodiment, MEL functional unit 44, the output can limit curves L1, Teitai stability limit curve L2, in consideration of the protection relay operation curve L3, the no-load _{P 0} and the rated active power _{P 1} 2 points Q ₀ and Q ₁ corresponding to the above are selected, and the MEL curve L0 connecting both points Q ₀ and Q ₁ with a straight line is set, but not limited to this, for example, corresponding to 50% load active power The point Q ₂ can be further obtained, and the MEL curve L 0 can be set by a broken line connecting these points Q ₀ , Q ₂ , Q ₁ with straight lines (see step D 4 in FIG. 9 and FIG. 10).

By setting the MEL curve L0 as a broken line as in the fourth embodiment, it is possible to further expand the reactive power adjustment range on the phase advance side than in the first to third embodiments.
Since other configurations and operations are the same as those in the first embodiment, detailed description thereof is omitted here.

Embodiment 5. FIG.
FIG. 11 is a flowchart showing the setting operation of the low excitation limit value in the excitation control apparatus of the fifth embodiment, and FIG. 12 is an explanatory diagram for setting the low excitation limit value in the fifth embodiment.

In the first to fourth embodiments described above, the MEL function unit 44 sets the MEL curve L0 by connecting a plurality of points with straight lines, but is not limited thereto, and sets the MEL curve L0 with an arc passing through the plurality of points. You can also For example, the two points Q ₀ and Q ₁ corresponding to the no-load P ₀ and the rated active power P ₁ are selected, and the MEL curve L 0 is set by the arc of the center R passing through both points Q ₀ and Q ₁ (FIG. 11). Step E4 and FIG. 12).

According to the fifth embodiment, even when the output possible limit curve L1 and the steady state stability limit curve L2 of the synchronous generator 1 are set to arcs, the curves L1 and L2 Therefore, it is possible to appropriately set the MEL curve L0, so that it becomes less necessary to secure an excessive margin when setting the MEL curve L0, and the reactive power adjustment range on the phase advance side can be further expanded.
Since other configurations and operations are the same as those in the first embodiment, detailed description thereof is omitted here.

Embodiment 6 FIG.
FIG. 13 is a flowchart showing the setting operation of the low excitation limit value in the excitation control apparatus of the sixth embodiment, and FIG. 14 is an explanatory diagram when setting the low excitation limit value in the sixth embodiment.

In the above first to fifth embodiments, the MEL function unit 44 calculates and sets the MEL curve L0 each time the steady state stability limit curve L2 is obtained. Instead, the MEL function A plurality (four in this example) of MEL curves L0 _{1 to} L0 ₄ are preset and registered in the unit 44, and each time the steady state stability limit curve L2 is obtained, the obtained steady state stability limit curve L2 One of the plurality of MEL curves L0 _{1 to} L0 ₄ may be selected according to the value (see step F5 in FIG. 13 and FIG. 14).

According to the sixth embodiment, the MEL function unit 44 only needs to select one of a plurality of preset MEL curves L0. Therefore, every time the steady state stability limit curve L2 is obtained, There is an advantage that the calculation process for determining the MEL curve L0 can be simplified as compared with the case where the MEL curve L0 is calculated and set each time.
Since other configurations and operations are the same as those in the first embodiment, detailed description thereof is omitted here.

Embodiment 7 FIG.
FIG. 15 is a flowchart showing the setting operation of the low excitation limit value in the excitation control apparatus of the seventh embodiment, and FIG. 16 is an explanatory diagram for setting the low excitation limit value in the seventh embodiment.

  In the first to sixth embodiments described above, every time the steady state stability limit curve L2 is obtained, the MEL function unit 44 obtains the MEL curve L0 represented by a straight line, a broken line, or an arc. In addition to the above, in the MEL function unit 44, the current excitation power value of the synchronous generator 1 and the current steady state stability limit curve L2 are used to determine the low excitation limit value under the current active power. Can be set individually.

  For example, when the current active power in the operation state of the synchronous generator 1 is Pa, the output possible limit curve L1, the steady state stability limit curve L2, and the protection relay operation curve L3 are taken into consideration, and this active power Pa is supported. The value of each reactive power on the steady state stability limit curve L2 is obtained, and the value of this reactive power is set as a phase advanceable point, and the low excitation limit value Qa including a certain margin with respect to this phase advanceable point Set. Similarly, when the active power in the current operating state is Pb, the value of each reactive power on the steady-state stability limit curve L2 corresponding to this active power Pb is obtained, and this reactive power value is determined as a phase advanceable point And a low excitation limit value Qb including a certain margin is set for the phase advanceable point (see step G4 in FIG. 15 and FIG. 16).

As described above, in the seventh embodiment, the MEL function unit 44 determines the current effective power during operation from the current active power value of the synchronous generator 1 and the current value of the steady state stability limit curve L2. Since the low excitation limit value under electric power is sequentially set individually, the most suitable low excitation limit value reflecting the current operation state and power system state of the synchronous generator can be set individually. For this reason, compared with Embodiment 1-6, it becomes possible to expand the adjustment range of the reactive power in the phase advance side to the maximum.
Since other configurations and operations are the same as those in the first embodiment, detailed description thereof is omitted here.

Embodiment 8 FIG.
FIG. 17 is a flowchart showing the setting operation of the low excitation limit value in the excitation control apparatus of the eighth embodiment, and FIG. 18 is an explanatory diagram for setting the low excitation limit value in the eighth embodiment.

  In the above-described first to sixth embodiments, the values of each reactive power on the steady-state stability limit curve L2 are obtained, and these values are set as phase advanceable points, and are constant with respect to each phase advanceable point. The MEL curve L0 is set in consideration of the margin of the current, but during the actual operation of the synchronous generator 1, the output voltage of the synchronous generator 1 is adjusted by the AVR 45, so the dynamic stability limit curve L2 It is possible to set the MEL curve L0 reflecting '.

That is, in the eighth embodiment, the MEL function unit 44 inputs the current impedance Xe of the power system measured by an external device (not shown) (step H2), and is detected by the impedance Xe and the voltage detector 5. Based on the value with the output voltage Vg, the dynamic stability limit curve L2 ′ shown in FIG. 18 is calculated (step H3). Subsequently, the MEL function unit 44 considers the output possible limit curve L1, the dynamic stability limit curve L2 ′, and the protection relay operation curve L3, and the dynamic stability limit corresponding to the no-load P ₀ and the rated active power P _1. The values of each reactive power on the curve L2 ′ are obtained, and these values are set as phase advanceable points (step H4), and two points Q ₀ , including a certain margin with respect to each phase advanceable point, to select the Q _1. Then, set the MEL curve L0 connecting the both points _Q 0, _{Q 1} by a straight line (step H5).

  Instead of setting the MEL curve L0, as in the case of the seventh embodiment, in the MEL function unit 44, the current active power value of the synchronous generator 1 and the current dynamic stability limit curve L2 ′ The low excitation limit value under the current active power may be set individually and sequentially from the value.

As described above, in the eighth embodiment, in consideration of the output voltage adjustment function by the AVR 45, the MEL which reflects the dynamic stability limit curve L2 ′ having a wider phase advanceable operation region than the steady state stability limit curve L2. Since the curve L0 can be set dynamically, or the low excitation limit value can be sequentially set individually, the reactive power adjustment range on the phase advance side can be further expanded.
Since other configurations and operations are the same as those in the first embodiment, detailed description thereof is omitted here.

Embodiment 9 FIG.
FIG. 19 is a flowchart showing the setting operation of the low excitation limit value in the excitation control apparatus of the ninth embodiment, and FIG. 20 is an explanatory diagram when setting the low excitation limit value in the ninth embodiment.

  In the above-described eighth embodiment, the current impedance Xe of the power system measured by an external device (not shown) is input to the MEL function unit 44 (see step H2 in FIG. 17). 3, the impedance calculation unit 46 is provided, and the impedance Xe of the power system is calculated from the change ΔVg of the output voltage Vg of the synchronous generator 1 and the change ΔQg of the reactive power Qg according to the above-described equation (1). The dynamic stability limit curve L2 ′ may be calculated based on the calculated impedance Xe and the value of the output voltage Vg detected by the voltage detector 5 (step I3). .

  Alternatively, as in the case of the above-described second embodiment, if the impedance changes depending on the power system pattern, each impedance corresponding to a plurality of power system patterns is set in advance in the MEL function unit 44. The impedance corresponding to this may be set by switching.

Thereby, in addition to the effects of the eighth embodiment, the effects described in the second and third embodiments can be added.
Since other configurations and operations are the same as those in the first embodiment, detailed description thereof is omitted here.

Embodiment 10 FIG.
FIG. 21 is a flowchart showing the setting operation of the low excitation limit value in the excitation control apparatus of the tenth embodiment, and FIG. 22 is an explanatory diagram for setting the low excitation limit value in the tenth embodiment.

  In the above first to ninth embodiments, the output possible limit curve L1 of the synchronous generator 1 is fixed, but the output possible limit curve L1 of the synchronous generator 1 is a condition such as the pressure or temperature of the cooling gas. It depends on.

Therefore, in the tenth embodiment, the MEL function unit 44 inputs an operation state signal such as the pressure and temperature of the cooling gas of the synchronous generator 1 (step J2), and based on this, the current output possible limit curve L1 is obtained (step J3). Then, this output can limit curve L1, and Teitai considering the stability limit curve L2 and the protection relay operation curve L3, the invalid on no-load P ₀ and the output can limit curve L1 corresponding to the rated active power P ₁ Electric power values are obtained, and these values are set as the phase advanceable points (step J4). Then, two points Q ₀ and Q ₁ including a certain margin are selected for each of these phase advanceable points, and a MEL curve L0 connecting both points Q ₀ and Q ₁ with a straight line is set (step) J5).

  Instead of setting the MEL curve L0, the MEL function unit 44 uses the current active power value of the synchronous generator 1 and the current output possible limit curve L1 value as in the seventh embodiment. The low excitation limit value under the current effective power may be set individually and sequentially.

As described above, in the tenth embodiment, the output possible limit curve L1 is sequentially calculated, and the MEL curve L0 reflecting the calculated current output possible limit curve L1 or the low value under the current effective power is calculated. Since the excitation limit values are set individually one after another, the operating conditions of the synchronous generator 1 are taken into account even when the phase advance operation region has to be narrowed, such as when the cooling gas pressure of the synchronous generator 1 decreases. It is possible to set the appropriate MEL curve L0.
Since other configurations and operations are the same as those in the first embodiment, detailed description thereof is omitted here.

Embodiment 11 FIG.
FIG. 23 is a flowchart showing the setting operation of the low excitation limit value in the excitation control apparatus of the eleventh embodiment, and FIG. 24 is an explanatory diagram for setting the low excitation limit value in the eleventh embodiment.

In the tenth embodiment, the MEL curve L0 is set based on the output possible limit curve L1, assuming that the steady state stability limit curve L2 of the synchronous generator 1 is fixed. On the other hand, in the eleventh embodiment, the MEL function unit 44 inputs the current impedance Xe of the electric power system and inputs the operation state signals such as the pressure and temperature of the cooling gas of the synchronous generator 1. (Step K2 ′), both the current steady state stability limit curve L2 and the output possible limit curve L1 of the synchronous generator 1 are calculated (Step K3, K3 ′), and the no-load P ₀ and the rated active power P ₁ are calculated. The reactive power values on the output possible limit curve L1 and the steady-state stability limit curve L2 corresponding to are obtained (step K4), and the reactive power values at these points are compared, and a margin is included. Two points Q ₀ and Q ₁ are selected, and an MEL curve L0 connecting both points Q ₀ and Q ₁ with a straight line is set (step K5).

Thus, in the eleventh embodiment, the MEL curve L0 considering both the current output possible limit curve L1 and the current steady state stability limit curve L2 of the synchronous generator 1 is dynamically set. It is possible to set an optimal MEL curve L0.
Since other configurations and operations are the same as those in the first embodiment, detailed description thereof is omitted here.

Embodiment 12 FIG.
FIG. 25 is a flowchart showing the setting operation of the low excitation limit value in the excitation control apparatus of the twelfth embodiment, and FIG. 26 is an explanatory diagram for setting the low excitation limit value in the twelfth embodiment.

In the eleventh embodiment, both the current output possible limit curve L1 and the steady state stability limit curve L2 of the synchronous generator 1 are calculated (see steps K3 and K3 ′ in FIG. 23). On the other hand, in the twelfth embodiment, both the current output possible limit curve L1 and the current dynamic stability limit curve L2 ′ of the synchronous generator 1 are calculated (steps M3 and M3 ′), and no load P ₀ and the rated active power P ₁ to determine the value of the reactive power of each of the above possible output limit curve L1 corresponding and dynamic stability limit curve L2 '(step M4), compares the value of reactive power of each of these points Then, two points Q ₀ and Q ₁ including a margin are selected, and an MEL curve L0 connecting both points Q ₀ and Q ₁ with a straight line is set (step M5).

As described above, in the twelfth embodiment, in addition to the current output possible limit curve L1, in consideration of the output voltage adjustment function by the AVR 45, a wide dynamic range of the phase advanceable operation range is also obtained by the steady state stability limit curve L2. Since the MEL curve L0 reflecting the stability limit curve L2 ′ can be set dynamically, the reactive power adjustment range on the phase advance side can be further expanded as compared with the eleventh embodiment.
Since other configurations and operations are the same as those in the first embodiment, detailed description thereof is omitted here.

  In addition, this invention is not limited to the structure of said each Embodiment 1-12, It is possible to combine the structure of each Embodiment 1-12 suitably.

It is a block diagram which shows the whole excitation control apparatus in Embodiment 1 of this invention. It is a flowchart which shows the setting operation | movement of the excitation limit value in the excitation control apparatus of Embodiment 1 of this invention. It is explanatory drawing in the case of setting the low excitation limit value in Embodiment 1 of this invention. It is a flowchart which shows the setting operation | movement of the low excitation limit value in the excitation control apparatus of Embodiment 2 of this invention. It is explanatory drawing in the case of setting the low excitation limit value in Embodiment 2 of this invention. It is a block diagram which shows the whole excitation control apparatus in Embodiment 3 of this invention. It is a flowchart which shows the setting operation | movement of the low excitation limit value in the excitation control apparatus of Embodiment 3 of this invention. It is explanatory drawing in the case of setting the low excitation limit value in Embodiment 3 of this invention. It is a flowchart which shows the setting operation | movement of the low excitation limit value in the excitation control apparatus of Embodiment 4 of this invention. It is explanatory drawing in the case of setting the low excitation limit value in Embodiment 4 of this invention. It is a flowchart which shows the setting operation | movement of the low excitation limit value in the excitation control apparatus of Embodiment 5 of this invention. It is explanatory drawing in the case of setting the low excitation limit value in Embodiment 5 of this invention. It is a flowchart which shows the setting operation | movement of the low excitation limit value in the excitation control apparatus of Embodiment 6 of this invention. It is explanatory drawing in the case of setting the low excitation limit value in Embodiment 6 of this invention. It is a flowchart which shows the setting operation | movement of the low excitation limit value in the excitation control apparatus of Embodiment 7 of this invention. It is explanatory drawing in the case of setting the low excitation limit value in Embodiment 7 of this invention. It is a flowchart which shows the setting operation | movement of the low excitation limit value in the excitation control apparatus of Embodiment 8 of this invention. It is explanatory drawing in the case of setting the low excitation limit value in Embodiment 8 of this invention. It is a flowchart which shows the setting operation | movement of the low excitation limit value in the excitation control apparatus of Embodiment 9 of this invention. It is explanatory drawing in the case of setting the low excitation limit value in Embodiment 9 of this invention. It is a flowchart which shows the setting operation | movement of the low excitation limit value in the excitation control apparatus of Embodiment 10 of this invention. It is explanatory drawing in the case of setting the low excitation limit value in Embodiment 10 of this invention. It is a flowchart which shows the setting operation | movement of the low excitation limit value in the excitation control apparatus of Embodiment 11 of this invention. It is explanatory drawing in the case of setting the low excitation limit value in Embodiment 11 of this invention. It is a flowchart which shows the setting operation | movement of the low excitation limit value in the excitation control apparatus of Embodiment 12 of this invention. It is explanatory drawing in the case of setting the low excitation limit value in Embodiment 12 of this invention. It is a figure for demonstrating how to set the low excitation limit value in the conventional synchronous generator.

Explanation of symbols

1 synchronous generator, 2 excitation winding, 3 excitation machine, 4 excitation control device,
5 voltage detector (PT), 6 current detector (CT), 41 voltage setter, 42 subtractor, 43 power calculator,
44 MEL function section (stationary stability limit calculation means, dynamic stability limit calculation means, output possible limit calculation means, low excitation limit value setting means, impedance selection means),
45 Automatic voltage regulator (AVR), 46 Impedance calculator.

Claims (9)

Stability limit calculation means for calculating the value of the steady state stability limit or dynamic stability limit based on the output value of the synchronous generator and the impedance of the power system, and the steady state calculated by the stability limit calculation means Based on the value of the stability limit or dynamic stability limit, a low excitation limit value setting means for setting a low excitation limit value for limiting the low excitation operation range of the synchronous generator reflecting the value, and the low excitation limit Automatic voltage adjusting means for limiting the excitation current supplied to the excitation winding of the synchronous generator and adjusting the output voltage so as not to exceed the low excitation limit value set by the value setting means. The synchronous generator excitation control device. 2. An electric power system switching pattern is registered in advance, and impedance selection means is provided for determining the impedance corresponding to the switching pattern according to selection of the switching pattern and giving the impedance to the stability limit calculation means. An excitation control device for a synchronous generator as described. 2. The synchronous power generation according to claim 1, further comprising impedance calculation means for calculating an impedance of the power system from a change in output voltage of the synchronous generator and a change in reactive power and supplying the calculated impedance to the stability limit calculation means. Excitation control device. The low excitation limit value setting means is based on the values of a plurality of points of the steady state stability limit or the dynamic stability limit calculated by the stability limit calculation means, and the low excitation limit value setting means includes a straight line passing through the plurality of points. The excitation control device for a synchronous generator according to any one of claims 1 to 3, wherein a limit value is set. The low excitation limit value setting means is based on the values of a plurality of points of the steady state stability limit or dynamic stability limit calculated by the stability limit calculation means, and the low excitation limit value setting means has an arc passing through the plurality of points. The excitation control device for a synchronous generator according to any one of claims 1 to 3, wherein a limit value is set. The low excitation limit value setting means includes a plurality of preset low excitation limit curves, and the low excitation limit value setting means corresponds to the steady state stability limit or the kinetic stability limit value calculated by the stability limit calculation means. The excitation control device for a synchronous generator according to any one of claims 1 to 3, wherein one of a plurality of low excitation limit curves is selected. The low excitation limit value setting means is based on the current active power value of the synchronous generator and the current steady state stability limit or current dynamic stability limit value calculated by the stability limit calculation means. 4. The excitation control device for a synchronous generator according to any one of claims 1 to 3, wherein the low excitation limit value under the current active power is set individually and sequentially. . In place of the stability limit calculation means, the low excitation limit value setting is provided with output possible limit calculation means for calculating an output possible limit value that defines an output possible range such as the pressure and temperature of the cooling gas of the synchronous generator. The means is for setting a low excitation limit value for limiting the low excitation operation range of the synchronous generator reflecting the value based on the value of the output possible limit calculated by the output possible limit calculation means. The excitation control device for a synchronous generator according to any one of claims 1 to 7, wherein: An output possible limit calculating means for calculating an output possible limit for defining an output possible range such as the pressure and temperature of the cooling gas of the synchronous generator is provided, and the low excitation limit value setting means is calculated by the stability limit calculating means. Based on the values of both the steady state stability limit or dynamic stability limit determined and the output possible limit calculated by the output possible limit calculating means, the low excitation operation range of the synchronous generator reflecting these values is reflected. The excitation control device for a synchronous generator according to any one of claims 1 to 7, wherein a low excitation limit value for limiting the current is set.

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