JP6081124B2 - System stabilization apparatus and system stabilization method - Google Patents

Description

  Embodiments described herein relate generally to a system stabilization apparatus and a system stabilization method for a power system.

  2. Description of the Related Art Conventionally, a system stabilization system has been introduced in order to prevent a wide-area power outage when a serious accident occurs with the establishment of a new power source in the power system. Various types of power system stabilization systems are employed. In the power system stabilization system, the predicted value of the generator phase angle fluctuation at the estimated reclosing time of the accident transmission line, the total output of the generator before the accident, and the power system side from the generator near-end bus In some cases, a driving point reactance value after reclosing and a parameter including a preset generator constant are input to determine the stability after reclosing.

  In addition, when the accident protection by the main protection is not carried out and the rear-end protection operation is reached, data on the generator output or the transmission line active power during the accident is accumulated, and the phase angle of the generator is based on the accumulated data. There is also a power system stabilization system that calculates and uses output information. This power system stabilization system estimates a P-δ curve during and after an accident using information on the phase angle and output of the generator, and based on the estimated P-δ curve, acceleration energy and deceleration energy Is calculated. And this electric power system stabilization system performs stability discrimination | determination based on magnitude comparison of these two types of energy, and interrupts a generator from an electric power system when it is unstable.

  In the conventional system stabilization system, maintaining the transient stability of the system and controlling the frequency around 50 Hz or 60 Hz have been main problems. On the other hand, nowadays, it is necessary to deal with complex problems including voltage, such as the relationship between transient stability and voltage fluctuation, and the relationship between frequency stabilization and voltage fluctuation. Therefore, it is essential to construct a new system stabilization system that integrates multiple functions.

Japanese Patent Laid-Open No. 2004-282887 JP 2010-57253 A

  When an accident occurs due to the occurrence of lightning strikes or contact of an obstacle with a power transmission line in the power system, the system configuration changes compared to the normal time. In some cases, the voltage and frequency in the grid deviate from the operable range of the generator due to an imbalance between the output energy from the generator and the energy consumed by the load, which is highly important for grid operation. There is a possibility that the generator will step out and cause a large-scale power outage.

  Regarding stabilization control for preventing this, there is control called first-stage control. In this first-stage control, based on information such as the rated output and operating status of the generator connected to the grid and the power flow, voltage, and frequency in the grid that reflects this status, The amount of power control (hereinafter referred to as electric control) necessary for severe accidents such as position and 3φ4LG (three-phase four-wire ground fault) is determined in advance. In the first-stage control, when an accident occurs, the amount of electricity measured immediately before is used to determine whether or not electric control is necessary.

  The first stage control is implemented after the accident. However, if the angular velocity deviation or internal phase angle of an equivalent single-generator that tends to diverge due to the occurrence of an accident does not converge due to the first-stage control, additional control (hereinafter referred to as second-stage control) May be required).

  In implementing the second stage control, the amount of electric control is determined based on information such as power flow and voltage in the system after the accident. The accident track is reopened after a certain period of time. However, if the accident continues at this time, the track will be opened again (failure of reclosing), and depending on the timing, the system may become unstable due to the disturbance at that time.

  In the stability determination based on the P-δ curve described above, the drive point reactance value is used to calculate the stability after reclosing, and the stability determination is performed based on the equal area method. However, in this stability determination, the target is limited, for example, the accident line is a power line, and a plurality of generators in the same power plant are subject to electric control. For this reason, stability determination based on the P-δ curve is difficult to apply to an arbitrary system composed of a plurality of loads and power plants. Regardless of the success or failure of the reclosing, if the amount of electric control is determined on the assumption of the reclosing failure, excessive electric control will occur when the reclosing succeeds, and there is a possibility that the power supply may be hindered.

  The problem to be solved by the present invention is a system stabilization device and system stabilization that can stabilize a system while suppressing excessive power control in an arbitrary system composed of a plurality of loads and power plants. It is to provide a conversion method.

According to the embodiment, the grid stabilization device includes a generator connected to the power system in which the accident has occurred when an accident occurs in the power system in which the generator is connected via the transmission line. It has a measuring means for measuring the amount of electricity and the amount of electricity of the transmission line connected to the power system. This system stabilizing device is based on the measurement result of the measuring means, and based on the calculation result of the angular velocity deviation and the internal phase angle of the generator after the accident occurred, the accident point section was opened after the accident occurred. By comparing the calculated internal phase angle with a predetermined value up to a predetermined step-out determination time, and determining whether the calculated angular velocity deviation tends to increase at the step-out determination time The step-out determination means determines whether the electric power system at the step-out determination time is stable or unstable.

  This system stabilizing device predicts the internal phase angle of the generator at a predetermined stability determination time after the out-of-step determination time when the out-of-step determination means determines that the power system is unstable. It has a power generator target determination means. The power control target generator determining means determines whether the power system is stable or unstable at the stability determination time by comparing the predicted internal phase angle with a predetermined value. When the power generation target determining means determines that the power system is unstable, the power control target generator determines the power system at a predetermined power control execution time between the step-out determination time and the stability determination time. A generator to be subjected to power supply control is determined in consideration of the priority of electric control determined for each of the generators for stabilization. The power control target generator determining means repeats determining the generator until it is determined that the power system is stable at the stability determination time.

  This system stabilization device, when the power system is determined to be stable by the control target generator determining means, the reclosing when the fault line reclosing failure after the power control is assumed A reclosing stability evaluation means for predicting the internal phase angle of the generator at a predetermined reclosing stability determination time after the failure is provided. The reclosing stability evaluation means compares the predicted internal phase angle at the reclosing stability determination time with a predetermined value, so that the power system is stable or unstable at the reclosing stability determination time. Is determined. The re-closing stability evaluation means is defined for each of the generators for stabilizing the power system at the time of power supply control when it is determined that the power system is unstable. The power generator control target generator is determined again in consideration of power control priority. The re-closing stability evaluation means repeats the determination of the generator to be subject to power control until the power system is determined to be stable at the re-closing stability determination time.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to stabilize a system | strain, suppressing the excessive electric control in the arbitrary systems | strains comprised by several load and power plants.

The figure for demonstrating the structural example of the system | strain stabilization apparatus in embodiment. The figure which shows an example of the time characteristic of the phase angle difference between generators. The figure for demonstrating 1 machine infinite bus system. The flowchart which shows an example of the operation | movement procedure of the system | strain stabilization apparatus in embodiment. Diagram for explaining the stability determination time to predict the internal phase angle at t _s, to less than the threshold value, changes the power generator to be disconnected from the system. The figure for demonstrating the determination regarding the necessity of additional electric control by reclosing failure.

Hereinafter, embodiments will be described with reference to the drawings.
Drawing 1 is a figure for explaining the example of composition of the system stabilization device in an embodiment.
In this system stabilizing device, n generators 1a, 1b,..., 1n, which are a collection of several generators, and n circuit breakers 2a, 2b are connected on a one-to-one basis to interconnection buses 5a, 5b,... 5n via power transmission lines 3a1, 3b1,. Loads (L) 4a, 4b,... 4n are connected to the interconnection buses 5a, 5b,.

Interconnection buses 5a, 5b,... 5n are connected to interconnection bus 6 via power transmission lines 3a2, 3b2,.
Two power transmission lines 7 a and 7 b are connected to the interconnection bus 6. Each transmission line, that is, the transmission lines 3a1, 3b1,... 3n1, the transmission lines 3a2, 3b2,... 3n2, and the transmission lines 7a, 7b include impedance.

In addition, a load (L) 4A is connected to the interconnection bus 6.
Two transmission lines 7 a and 7 b are connected to the interconnection bus 8. Other power system 9 is also connected to interconnection bus 8.

The accident assumed in the present embodiment is assumed to occur in the section of the transmission lines 7a and 7b.
The system stabilizing device 10 includes a data measurement unit 11, a data transmission unit 12, an electric control amount determination unit 13, a generator rated output / priority data storage unit 14, and a control command transmission unit 18. The generator rated output / priority data storage unit 14 is realized by a storage device such as a nonvolatile memory.

Data measurement unit 11, each of the output data of n-number generator 1a~1n connected to the power system 9, and the transmission line 7a, 7b of the tide and the voltage of the interconnection bus 6 and interconnection bus 8 Measure data such as.
The data transmission unit 12 transmits the data measured by the data measurement unit 11 to the electric control amount determination unit 13.
The electric control amount determination unit 13 determines the electric control amount based on the data transmitted by the data transmission unit 12.
Based on the electric control amount determined by the electric control amount determination unit 13, the control command transmission unit 18 sends a cutoff command to the generator to be controlled.

  The electric control amount determination unit 13 uses output data of the generators 1a to 1n to determine the electric control amount. However, at this time, the calculation is performed assuming that the data of the generators 1a to 1n is equivalent to the data of the equivalent one-generator 301 replaced with one generator, and this data is used.

  For the equivalent single-generator 301, the data measurement unit 11 performs measurement every several tens of milliseconds so as to prevent the step-out at the first wave after the accident, and holds the data in the internal memory. The data transmission unit 12 transmits the data measured by the data measurement unit 11 to the control amount determination unit 13.

The electric control amount determination unit 13 includes a step-out determination unit 15, an electric control target generator determination unit 16, and a reclosing stability evaluation unit 17.
The control target generator determining unit 16 and the reclosing stability evaluation unit 17 refer to each other data stored in the generator rated output / priority data storage unit 14.

The electric control amount determination unit 13 calculates necessary variables as follows before the operation starts.
First, output values Pa0 to Pn0 of electric quantities before the occurrence of an accident of the n generators 1a to 1n are measured by the data measuring unit 11.
Further, the data measuring unit 11 performs measurement even during an accident. In FIG. 6A described later, the effective output power PG of the equivalent single-generator 301 at the time of occurrence of an accident will be described.

Next, after the accident occurs, the conditions in which the output values of the generators 1a to 1n measured by the data measuring unit 11 at intervals of Δt expressed by the following formula (1) are Pa (t) to Pn (t) are set. Think. In this condition, the electrically controlled amount determining section 13, agitation of the generator 1a~1n at time _{t k} time after the accident, that is calculated according to the angular speed deviation .omega.G _{(t k)} the following equation (3). The electronically controlled amount determining section 13, the time _{t k} generator 1a~1n internal phase angle at δ a _{(t k)} is calculated according to equation (4).
t _k = t _k−1 + Δt (1)

ωG (t _k ) = ωg (t _k−1 ) + Δω (3)

The data of each generator of the target system, the inertia constant M of the equivalent single-generator 301 (see Equation (2)), etc. are calculated before the accident occurs and stored in the generator rated output / priority data storage unit 14 in advance. Is done.
The inertia constant M is expressed by the following equation (5) using the inertia constant M _{gi of} each of the generators 1a to 1n converted on the basis of the equivalent one-generator generator capacity.

In formula (5), i is a generator number, and n is the number of generators.
Next, the information regarding the time required in the electric control amount determination part 13 in 2nd step control is shown. FIG. 2 is a diagram illustrating an example of time characteristics of the phase angle difference between the generators. In this figure, a diagram for explaining that to determine the need, unnecessary in the second stage control using the data up to the out-of-step detection time t _l.
First, after the accident occurrence time t _h, the fault point section is opened as the control of the first stage in the open time t _u. Here, the out-of-step detection time after the open and t _l. Also, the time to implement the subsequent second stage control and t _2. Further, the t _s a stability determination time is the time required for the prediction after the second stage control execution time t _2. In addition, the reclosing execution time of the accident point of the stability determination time t _s after a t _r.
When the reclosing is performed, if the accident has not been removed, it is determined that the reclosing has failed and it is necessary to open the line again. The time to open the line again at the time of the re-closure failure and re-open time t _o.

Further, the power system during reclosing failure and reclosing stability determination time t _p the time to assume determination of whether unstable or stable. In addition, the electric control amount determination unit 13 uses measurement data before the step-out determination time t ₁ when performing the prediction.

Next, the concept of contracting each of the generators 1a to 1n, the circuit breakers 2a to 2n, and the power transmission lines 3a1 to 3n1 illustrated in FIG. 1 will be described. FIG. 3 is a diagram for explaining a one-machine infinite bus system.
The equivalent one-machine generator 301 is connected to the interconnection bus 6 together with the d-axis transient reactance X _d ′ G302. The power system 9 in FIG. 1 includes all generators other than the target system. The combined equivalent inertia constant can be assumed to be much larger than the equivalent inertia constant of the generators 1a to 1n in the target system. Therefore, the power system 9 side from the interconnection bus 6 shown in FIG. 1 is modeled by the interconnection bus 6 corresponding to an infinite bus. Further, the generators 1a to 1n shown in FIG.

Based on the rated capacity SGR _i (MVA), the rated output PGR _i (MW), and the inertia constant M _i (s) of the generators 1 a to 1 n in the target system, the rated capacity SGRT (MVA) of the equivalent one-generator 301 Is represented by the following equation (6). Further, the rated output PGRT (MW) of the equivalent single-generator 301 is expressed by the following equation (7). Further, the equivalent inertia constant M (s) of the equivalent single-generator 301 is represented by the following formula (8).

Further, based on the active power output PG _i 0 (MW) of the generators 1a to 1n, which is the measurement value before the occurrence of the accident, the initial value P _m 0 of the mechanical input P _m of the equivalent one-machine generator 301 is expressed by the following equation: It is indicated by (9).

Based on the generator 1a~1n active power output _PG i (MW) is the measurement value after the accident, the effective output power PG _k The following equation at the measurement time _{t k} after an accident of the equivalent one-machine generator 301 ( 10).

As a representative example of a method for expressing the reduced model of the equivalent single-generator 301 shown in FIG. 3 by a mathematical formula, there is a simplified model represented by the following formula (11).

i is a generator number of n generators 1a-1n. n is the number of generators. M _i is an inertia constant. P _mi is a machine input. E _i is an internal voltage of the generators 1a to 1n. B _iJ is the susceptance part of the reduced Y matrix (reduced admittance) (= G + jB). The stability of the generator is determined by the difference between the reference phase that is the center of the system and the phase of the target generator.

Therefore, in general, for each of the phase angle and the angular frequency of the generator, the amount of change from the center of inertia (δ ₀ , ω ₀ ) of the system, which is expressed by the following equation (12), is introduced as a state variable. .

θ _i = δ _i −δ ₀ , ω = ω _i −ω ₀ ... (12)
However, δ ₀ and ω ₀ are calculated by the following equation (13).

  Information such as the output of the equivalent single-generator 301 and the generator end voltage is calculated in advance in the operating state before the accident. This information is registered in the generator rated output / priority data storage unit 14. Then, when the situation changes with the implementation of electric control after the accident occurs, the information setting is changed, and information such as the output of the equivalent one-generator generator 301 and the generator end voltage is recalculated and the generator is re-calculated. It is overwritten and updated on the rated output / priority data storage unit 14.

  The generator rated output / priority data storage unit 14 also includes information on the rated output of the generator connected to the system, whether or not the generator can be shut off at the time of an accident, and the shutting off priority when shutting off is possible. Is stored. When there is a change in the installation mode of the generator in operation, such as the addition or removal of a generator in the target system, the generator information on the database in the generator rated output / priority data storage unit 14 Updated from time to time.

The operation of the electric control amount determining unit 13 will be described using the flowchart shown in FIG.
As for the stabilization control in the event of an accident in the power system, as a result of the first stage control, the system may not be stable and additional power control may be required.

The step-out determination unit 15 has a function of determining whether or not the additional electric control is necessary. As shown in FIG. 2, the out-of-step determining unit 15 determines the angular velocity deviation ωG (t) and the internal phase angle δ of the equivalent single-generator 301 after the accident from the occurrence of the accident to the out-of-step determination time t ₁ . A plurality of pieces of measurement data obtained by the data measurement unit 11 are acquired (step S1).
The step-out determination unit 15 includes a prediction unit 151, a first comparison processing unit 152, and a second comparison processing unit 153. The prediction unit 151 predicts the angular velocity deviation ωG (t) and the internal phase angle δ after the measurement time using the acquired measurement data based on the set estimation equations (step S2).

  Examples of prediction methods include the following. The predicted value ωG (t) of the angular velocity deviation and the predicted value δ (t) of the internal phase angle of the generators 1a to 1n at time t are expressed as the following formulas (14) and (15).

ωG (t) = ωG (t _k−2 ) + α ₁ (t−t _k−2 ) + α ₂ (t−t _k−1 ) (t−t _k−2 )
... Formula (14)

here,

The first comparison processing unit 152 determines whether or not the internal phase angle of the equivalent single generator / generator 301 satisfies the condition that the threshold δ _limit has been exceeded by the step-out determination time t ₁ (step S3). In addition, the second comparison processing unit 153 determines whether or not the angular velocity deviation ωG (t _l ) at the step-out determination time t _l tends to increase, that is, satisfies the condition of dωG (t _l ) / dt> 0. Is determined (step S4). The step-out determination unit 15 determines that the power system is unstable at the step-out determination time t ₁ when both conditions are satisfied based on the determination results in S3 and S4. The both conditions, the internal phase angle of the equivalent one-machine generator 301, the out-of-step detection time _t exceeds the threshold value [delta] _limit before _l, and the out-of-step detection time _{t l} angular deviations in .omega.G _{(t l)} is increasing It is a condition that it exists in.

When step-out determination unit 15 and the power system is unstable is determined in the step-out determination time t _l, electronically controlled target generator determiner 16, electrically controlled to determine the generator required. The control target generator determination unit 16 includes a prediction unit 161, a comparison processing unit 162, and an electric control amount update unit 163. Prediction unit 161, was used in the step-out determination unit 15, using the internal phase angle of the equivalent one-machine generator 301, it predicts the transition of the internal phase angle to stability determination time t _s (step S5).

Stability determination time _{t s} until the angular deviation of the equivalent one-machine generator 301 .omega.G _{(t s)} is given by the following equation (16). The internal phase angle equivalent 1 aircraft generator 301 to stability determination time _{t s} [delta] _{(t s)} is given by the following equation (17).

P _m is the machine input of the equivalent single-machine generator 301. M is an equivalent inertia constant. PG _K is the effective output power at the measurement time _{t k} after the accident. ω ₀ is the angular velocity deviation before the accident occurred. ωG (t) is a predicted value of the angular velocity deviation at time t.

Equation (17) is the result of moving the equation (16) as shown by the following equation (18) and integrating with respect to t.

The data measuring unit 11 measures data between the occurrence of an accident and the step-out determination time t ₁ . Therefore, the prediction unit 161 uses measurement data up to the step-out determination time t ₁ . The predicting unit 161 calculates the angular velocity deviation ωG (t ₁ ) and the internal phase angle δ (t ₁ ) at the step-out determination time t ₁ using the above-described formulas (2) to (4).

Internal phase angle of the equivalent one-machine generator 301 at stability determination time _{t s} [delta] _{(t s)} is given by the following equation (19).

This equation (19) is obtained by replacing t in equation (17) with a step-out determination time t ₁ . 5 to predict the internal phase angle at stability determination time t _s, the internal phase angle, until less than the stability determining threshold set, for explaining that they would change the generator to cut off from the system The figure of is shown.
In the stability determination in the comparison processing unit 162, this stability determination threshold is used. The stability determination threshold is set by selecting appropriate data from a plurality of types of data based on information such as the generator operating state and power flow before the accident. For example, stability determination threshold in advance by simulation, and change and generator operating conditions and trends, and divided by the unstable and become stable Case Case, the boundary with respect to the internal phase angle δ (t _s) It is determined by selecting a value.

Comparison processing unit 162, as shown in FIG. 5 (a) and 5 (b), the stability determination time _{t s,} if the internal phase angle predicted [delta] _{(t s)} is smaller than the stability determining threshold (step S6 of NO), the power system in the stability determination time t _s is determined to be stable. The comparison processing unit 162, as shown in FIG. 5 (c), the at stability determination time _{t s,} if the internal phase angle predicted [delta] _{(t s)} is equal to or greater than the stability determining threshold (YES in step S6) , power system at stability determination time t _s is determined to be unstable.

If it is determined by the comparison processing unit 162 and the power system is unstable at stability determination time t _s is electrically controlled amount update unit 163, the generator rated power and the priority data storage unit 14, for each generator of, referring to the operating state of the priority and the rated output data and the generator to shut off from the system. Further, the power control amount update unit 163 refers to the output value of the active power with respect to the operating generator, and changes the generators to be disconnected from the system in order of decreasing power control amount (step S7).

Then, the prediction unit 161 uses the equation (17), re-predicting the internal phase angle of the equivalent one-machine generator 301 at stability determination time _{t s δ (t s).} Comparison processing unit 162 compares the the stability determination threshold internal phase angles this re prediction [delta] (t _s), the power system in a stable determination time t _s is again determined whether unstable or stable .

As the implementation of the re-prediction by the prediction unit 161, an operation using Expression (19) can be given. Since the third term on the right side of Equation (19) depends on the mechanical input P _m and the inertia constant M of the equivalent single-generator 301, the third term on the right side of Equation (19) when the generator that is shut off from the system is removed. The value of changes.

Excluding the generator to shut off, the effective output power PG _K While unchanged, mechanical input P _m is reduced. For example, when the generator 1f is shut off from the system among the generators 1a to 1n, if the rated output PGR _i is α, the power control amount is α. At this time, the machine input P _m ′ and the effective output power PG _K ′ of the new equivalent single-machine generator 301 are expressed by the following equation (20).

When the generator is disconnected from the system as described above, the output power PG _i for each generator increases in the equation (20). Therefore, the total amount of effective output power does not change, and PG _K = PG _K ′ shown in Expression (20).
Further, an equivalent inertia constant M ′ of the new equivalent single-machine generator 301 is expressed by the following formula (21).

When the out-of-step determination unit 15 determines that the second-stage control is necessary, the angular velocity deviation ωG (t _l ) at the out-of-step determination time t ₁ is increasing, and the equal sign in the equation (16) is sandwiched. Both values are positive values. Therefore, P _m > PG _K.

If the second-stage control is not performed as it is, the increasing tendency of the internal phase angle δ diverges unchanged. When the mechanical input P _m ′ decreases from P _m and becomes smaller than PG _K by shutting off the generator 1f from the system, the internal phase angle δ (t) tends to decrease. At this time, the power control amount update unit 163 changes the generator to be cut off from the system. The electronically controlled amount updating section 163, the power system in a stable determination time t _s until determined to be stable, sequentially repeating the calculation using equation (17).

When the power system at stability determination time t _s is determined by the comparison processing unit 162 to be stable, the generator to shut off from the system is electronically controlled target generator. Next electronically controlled quantity by interrupting the generator 1f from strains alpha, internal phase angle [delta] (t) is the internal phase angle at stability determination time t _s be a decreasing [delta] (t _s) is stable determination threshold value Not below. Therefore, the electric control amount update unit 163 changes the generator to be cut off from the system.

When the generator 1g is disconnected from the system, the rated output is β and the electric control amount is β. As shown in FIG. 5 (b), even if the re-prediction by the prediction unit 161 in this case, the comparison processing unit 162 determines that the electric power system becomes unstable in the stability determination time t _s. Further, the generator 1f and the generator 1g blocked from the system, when the electrically controlled amount is γ is lower than the stability determining threshold internal phase angle, as shown in FIG. 5 (c), the stability determination time t _s When the power system becomes stable, the comparison processing unit 162 determines. Based on the determination result, the control target generator determining unit 16 determines the generator 1f and the generator 1g as the control target generator.

FIG. 6 is a diagram for explaining the determination regarding the necessity of additional electric control due to reclosing failure in the reclosing stability evaluation unit 17. The re-closing stability evaluation unit 17 includes a prediction unit 171, a comparison processing unit 172, and an electric control amount update unit 173.
6 (a) is out-of-step detection time t _l later, reclosing stability determination time difference and mechanical input P _m of the equivalent one-machine generator 301 when the effective output power PG by performing additional electronically controlled to t _p The difference between the mechanical input _Pm and the effective output power PG of the equivalent one-machine generator 301 when no additional electric control is performed is shown.

Also, FIG. 6 (b), the step-out determination time t _l later, the angular velocity deviation ωG for performing additional electronically controlled to reclosing stability determination time t _p, the angular velocity deviation ωG when no additional electronically controlled The difference is shown.
FIG. 6 (c), the step-out determination time t _l later, and an internal phase angle δ in the case of performing additional electronically controlled to reclosing stability determination time t _p, and δ internal phase angle when no additional electronically controlled The difference is shown.

Next, an embodiment of the reclosing stability evaluation means in the reclosing stability evaluation unit 17 will be described. The angular velocity deviation ωG that tends to decrease after the second-stage control execution time t ₂ by the control target generator determination unit 16 is a time lapse as shown by the dotted line in FIG. 6B when the reclosing is successful. It is assumed that the trend will decrease with the increase. On the other hand, when the reclosing failure occurs, the angular velocity deviation ωG increases again as shown by the solid line portion in FIG.

As shown in FIG. 6A, the effective output power PG decreases due to the reclosing failure as in the case of the accident. In the present embodiment, the effective output power PG is assumed to be PG _f in the case of reclosing failure.

In equation (16), the effective output power PG _K in reclosing execution time _{t r} corresponds to PG _f. When the relationship of P _m ≈PG until the reclosing operation is changed to P _m > PG _f by the reclosing operation, the second term on the right side of the equation (16) contributes and becomes positive. From this, it can be seen that the angular velocity deviation ωG increases due to reclosing failure.

Receiving reclosing fails, the section including the fault point in reopening the time t _o is opened again available output power PG is increased. However, the effective output power PG is not necessarily the same output as before reclosing embodiment, sometimes the difference becomes larger with respect to the machine input P _m of the equivalent one-machine generator 301. Then, the degree of decrease in the angular velocity deviation ωG is weakened, and the decrease is weakened following the internal phase angle δ which is an integral value.

The internal phase angle δ increases if the difference between the mechanical input _Pm and the effective output power PG is large without returning to the relationship of P _m ≈PG before the reclosing in the equation (16). When the internal phase angle δ of the equivalent single generator / generator 301 increases due to a reclosing failure or when the degree of decrease decreases, the control target generator determination unit 16 determines that the power system is stable However, this power system becomes unstable again.
In order to avoid this, the predicting unit 171 of the reclosing stability evaluation unit 17 calculates the internal phase angle δ (t _p ) at the reclosing stability determination time t _p after the reopening time t _o using the equations (14) and (14). Estimate using (15) (step S8).

However, in between reclosing execution time _{t r} of reopening the time _{t o,} as in the case of accident, mechanical input _{P m} of the equivalent one-machine generator 301 and PG _r. In addition, the effective output power of the re-opening time t _o after PG is used as the value of the before reclosing execution time t _r.

The comparison processing unit 172 of the reclosing stability evaluation unit 17 calculates the predicted internal phase angle and the stability determination threshold value for each generator operating state set in the generator rated output / priority data storage unit 14 in advance. Make a comparison. Comparison processing unit 172, by performing this comparison, the power system in reclosing stability determination time t _p is discriminates whether unstable or stable (step S9).

In this embodiment, the stability determination threshold in reclosing stability determination time t _p, like the threshold used is electronically controlled target generator determining unit 16, in accordance with the information, such as an electrical generator operating conditions and power flow before the accident, a plurality Appropriate data is selected from various types of data. For example, the pre-simulation, any modifications to the power generator operating conditions and trends, and divided by the unstable and become stable Case Case regarding internal phase angle in reclosing stability determination time t _p δ (t _p) A boundary value is determined as a threshold value.

If it is determined that unstable by comparison processing unit 172, that is, if the internal phase angle in reclosing stability determination time t _p δ (t _p) is stable determination threshold value or more in reclosing stability determination time t _p (in step S9 YES), the electric control amount update unit 173 of the reclosing stability evaluation unit 17 performs additional electric control (step S10). Like the power control amount update unit 163 of the power control target generator determination unit 16, the power control amount update unit 173 prioritizes shutting off the generator from the generator rated output / priority data storage unit 14 from the system. degrees, with respect to the generator that is operating with the operating state of the rated output data, and the generator referring to the output value of the active power. Then, the power control amount update unit 173 changes the generator to be cut off in consideration of the order in which the power control amount decreases based on the reference result.

After performing the change, the prediction unit 171 performs the calculation of the mechanical input P _m of the equivalent single-machine generator 301 and the equivalent inertia constant M again. The prediction unit 171 again estimates the internal phase angle δ (t _p ) after the second stage control execution time t ₂ using the machine input P _m of the new equivalent single-generator 301 and the equivalent inertia constant M. . Comparison processing unit 172, the internal phase angle [delta] (t _p), by comparing the threshold value is set to the generator rated power, the priority data storage unit 14, the power in reclosing stability determination time t _p The system again determines whether the system is stable or unstable. Reclosing time stability evaluation unit 17, such a process, the comparison processing unit 172, the power system in reclosing stability determination time t _p is repeated sequentially until it can be determined to be in the stable. With the method described in this embodiment, the electric control amount determination unit 13 can determine the electric control amount according to the electric power generation target generator excluded from the electric power system (step S11).
Control command transmission unit 18 on the basis of the electrical control amount determined by the electronically controlled variable determining unit 13 transmits a command to cut off the required generator from the system to the circuit breaker 2 (step S12).

  As described above, in the system stabilizing device according to the embodiment, the required power control amount is determined when the second stage control needs to be performed due to the occurrence of an accident in any system composed of a plurality of loads and power plants. In addition, the necessary power control amount is added only when failure is assumed at the time of reclosing. Therefore, when the reclosing is successful, excessive power control is not performed, and when the reclosing fails, the system can be stabilized with a necessary power control amount.

  Although several embodiments of the invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 1a-1n ... Generator, 2a-2n ... Circuit breaker, 3a1-3n1 ... Load, 3a2-3n2 ... Power transmission line, 4a-4n, 4A ... Load, 5a-5n ... Interconnection bus, 6 ... Interconnection bus, 7a , 7b ... Transmission line, 8 ... Interconnection bus, 9 ... Power system, 10 ... System stabilization device, 11 ... Data measurement unit, 12 ... Data transmission unit, 13 ... Power control amount determination unit, 14 ... Generator rated output Priority data storage unit, 15 ... step-out determination unit, 16 ... control target generator determination unit, 17 ... reclosing stability evaluation unit, 18 ... control command transmission unit, 151 ... prediction unit, 152 ... first Comparison processing unit, 153... Second comparison processing unit, 161, 171... Prediction unit, 162, 172... Comparison processing unit, 163, 173 ... Electric control amount update unit, 301 ... Equivalent single machine generator, 302 ... d-axis transient reactance.

Claims (4)

When an accident occurs in a power system that is connected to a generator via a transmission line, the amount of electricity of the generator connected to the power system in which the accident has occurred and the transmission connected to the power system A measuring means for measuring the amount of electricity of the electric wire;
Based on the calculation result of the angular velocity deviation and internal phase angle of the generator after the occurrence of the accident based on the measurement result by the measuring means, from the occurrence of the accident to the predetermined step-out determination time after opening the section of the accident point And comparing the calculated internal phase angle with a predetermined value and determining whether the calculated angular velocity deviation tends to increase at the step-out determination time. Step-out determination means for determining whether the power system is stable or unstable;
When the out-of-step determining means determines that the power system is unstable, the internal phase angle of the generator at a predetermined stability determination time after the out-of-step determination time is predicted, and the predicted internal phase angle And the predetermined value to determine whether the power system is stable or unstable at the stability determination time, and when determining that the power system is unstable, the step-out determination The target of power control in consideration of the priority of power control determined for each of the generators for stabilizing the power system at a predetermined power control execution time between the time and the stability determination time A generator to be controlled to repeat the determination until the power system is determined to be stable at the stability determination time;
When it is determined by the control target generator determining means that the power system is stable, a predetermined reclosing after the reclosing failure when the reclosing failure of the accident line after the power supply control is assumed By predicting the internal phase angle of the generator at the stability determination time and comparing the predicted internal phase angle at the reclose stability determination time with a predetermined value, the power system is stabilized at the reclose stability determination time. Each of the generators for stabilizing the power system at the time when the power supply control is performed when the power system is determined to be unstable. The power generator control target generator is determined again in consideration of the given power control priority, and the power control target generator is determined again at the reclosing stability determination time. Force lineage system stabilizing device being characterized in that a reclosing time stability evaluating means repeated until determined to be stable. The reclosing stability evaluation means includes:
The generator at the reclosing stability determination time after the reclosing failure when assuming the failure of reclosing the accident line after the determined power control after determining the generator to be subjected to the power control. The internal phase angle is predicted again, and the predicted internal phase angle at the reclosing stability determination time is compared with a predetermined value, so that the power system is stable or unstable at the reclosing stability determination time. The system stabilization apparatus according to claim 1, wherein it is determined again whether or not it exists. The measuring means measures an amount of electricity equivalent to an equivalent one-generator of a generator connected to a power system in which an accident has occurred,
The step-out determination means includes
Based on the measurement result of the measuring means, the section of the accident point is released after the occurrence of the accident based on the calculation result of the angular velocity deviation and internal phase angle equivalent to the equivalent one-generator of the generator after the occurrence of the accident. Comparing the calculated internal phase angle with a predetermined value until a predetermined step-out determination time passed, and determining whether or not the calculated angular velocity deviation tends to increase at the step-out determination time The system according to claim 2, wherein it is determined whether additional power control is required for the power system by determining whether the power system is stable or unstable. Stabilizer. When an accident occurs in a power system that is connected to a generator via a transmission line, the amount of electricity of the generator connected to the power system in which the accident has occurred and the transmission connected to the power system Measure the amount of electricity in the wire,
Based on the calculation result of the angular velocity deviation and internal phase angle of the generator after the occurrence of the accident based on the measured result, from the occurrence of the accident to a predetermined step-out determination time after opening the section of the accident point And comparing the calculated internal phase angle with a predetermined value and determining whether the calculated angular velocity deviation tends to increase at the step-out determination time, thereby determining the power at the step-out determination time. Determine whether the system is stable or unstable,
When it is determined that the power system is unstable, the internal phase angle of the generator at a predetermined stability determination time after the step-out determination time is predicted, and the predicted internal phase angle is compared with a predetermined value. By determining whether the power system is stable or unstable at the stability determination time, and determining that the power system is unstable, the step-out determination time and the stability determination time are determined. The generator to be subject to power control is determined in consideration of the priority of power control determined for each of the generators for stabilizing the power system at a predetermined power control execution time between And repeating the determination of the generator until it is determined that the power system is stable at the stability determination time,
When it is determined that the power system is stable at the stability determination time, when a reclosing failure of the accident line after the power control is assumed, at a predetermined reclosing stability determination time after the reclosing failure By predicting the internal phase angle of the generator and comparing the predicted internal phase angle at the reclosing stability determination time with a predetermined value, it is determined whether the power system is stable at the reclosing stability determination time. It is determined whether the power system is stable, and when it is determined that the power system is unstable, the power control determined for each of the generators for stabilizing the power system at the time of the power supply control execution time. In consideration of the priority of the power system, the power system subject to power control is determined again and the power system subject to power control is determined again at the reclosing stability determination time. System stabilization method and repeating until judged to be stable.

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