JP2005223986A - Interconnection system for power system, and power control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain the power quality on the side of a large-capacity system, by minimizing the influence on the side of the large-capacity system, even if the balance between the power demand and the power supply changes within a small-capacity system, and to reduce cost, while maintaining the power quality on the side of the small-capacity system to a required level. <P>SOLUTION: An interconnecting device 150 for regulating the quantity of circulating power is connected, in series with an interconnection point 130 between the large-capacity system 110 and the small-capacity system 120, and a power detector 140 detects the quantity of circulating power passing this interconnecting device 150. An adder 160 extracts the difference between the detected value of the quantity of circulating power detected with the power detector 140 and the fixed command value of the quantity of circulating power inputted separately, and outputs the obtained difference. A controller 170 receives the input of the difference between the detected value of the quantity of circulating power from the adder 160 and the command value of the circulating power and generates a control output signal for zeroing this difference, thereby controlling the interconnecting device 150. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a grid interconnection method in the case where a small capacity power system generally called a microgrid or the like is connected to a large capacity power system such as a power company.

  In recent years, due to the widespread use of small-capacity power generation systems such as natural energy power generation and micro gas turbines and the deregulation of power, power in specific areas is covered by power generation in those areas, and only excess or deficiency is provided by large companies such as power companies. An interconnection system such as a so-called microgrid that can be accommodated from a capacity power system has been studied. In such a power system interconnection system, an operation service related to maintenance of power quality, such as frequency control, is traded as an ancillary service separately from trading of electric energy (see, for example, Patent Document 1). In addition, in such a power system interconnection system, the power generation amount and load amount in the region are adjusted so that fluctuations in the power flowing through the connection points with one or more power company systems are as small as possible. And driving is done.

  As a conventional method for reducing the fluctuation of the power flowing through the interconnection point, as shown in FIG. 9, the interconnection point between a large capacity system 110 such as an electric power company system and a small capacity system 120 having a smaller capacity than that. The power interchange amount in 130 is detected by the power detector 140, and the detected value is monitored by the monitoring device 900, and the power generation of the generators 121 and 122 in the small capacity system 120 according to the increase / decrease in the detected power interchange amount. A method of increasing or decreasing the output is generally adopted. In this method, when the power accommodation amount accommodated from the large capacity system 110 increases, the power generation output of the generators 121 and 122 in the small capacity system 120 is increased, and conversely, when the power accommodation amount decreases. Decreases the power generation output of the generators 121 and 122 (see, for example, Patent Document 2).

  Further, as a conventional method for finely adjusting the power generation output of the generator, a governor is generally used to control the rotation speed of the power generator to finely adjust the power output and stabilize it (for example, And Patent Document 3).

JP 2003-284244 A JP-A-7-177664 JP 2000-217260 A

  In the conventional power system interconnection system as described above, the frequency on the small-capacity system side is the same as the frequency on the large-capacity system side of an electric power company or the like, so that the power quality can be basically maintained. . However, since the power at the interconnection point is not always constant and fluctuates constantly, it is necessary to adjust the fluctuation by generator control on the large capacity system side. Bad load. Further, even from the small capacity system side, there is a problem that the running cost of the interconnection system becomes expensive because it is necessary to pay an extra cost as an ancillary service to the large capacity system side, that is, the power company.

  On the other hand, the reason for connecting a large capacity system such as a power company without operating a small capacity system alone is to prevent the frequency from fluctuating greatly when the power supply and demand balance is disrupted in the small capacity system. However, in recent years, an increasing number of loads are used by converting alternating current to direct current with an inverter or the like. Since such loads are less affected by frequency fluctuations, some frequency fluctuations can be tolerated. In spite of this, it can be said that the conventional interconnection system of the power system has an excessive quality in which the frequency fluctuation is suppressed to be smaller than necessary in the small capacity system, and the cost is accordingly increased.

  The object of the present invention is to minimize the influence on the large capacity system side even when the power supply and demand balance fluctuates in the small capacity system, thereby maintaining the power quality on the large capacity system side, It is intended to provide a power system interconnection system and a power control method capable of reducing the cost while maintaining the power quality of the power supply to a necessary level.

  In order to achieve the above object, the present invention detects the amount of power passing through the interconnection means connected in series to the interconnection point, and connects the detected value and the command value given separately. By controlling the system means, when the power supply-demand balance fluctuates in a small-capacity system, the supply-demand balance and frequency can be recovered quickly by controlling the rotational speed using the governor of the generator even if some frequency fluctuations occur. In this way, the required power quality can be maintained.

  The invention of claim 1 is an interconnection system of a power system in which a small capacity power system having a smaller capacity is connected to a large capacity power system, and includes an interconnection means, a power detection means, and a control means. It is a feature. Here, the interconnection means is means for adjusting the power accommodation amount by being connected in series to the interconnection point connecting the large-capacity and small-capacity power systems. The power detection means is means for detecting the amount of power interchanged through the interconnection means. The control means is means for controlling the interconnection means by generating a control output signal for making the power accommodation amount detected value detected by the power detection means equal to a separately provided power accommodation amount command value.

  According to the invention as described above, when the load in the small capacity system fluctuates and the power supply and demand balance in the small capacity system is disrupted, the power is supplied from the large capacity system through the connection means at the connection point. Since the power interchange amount is controlled to a constant command value, the frequency of the small capacity system temporarily fluctuates, but the power generation output is gradually adjusted by the rotational speed control by the governor of the generator in the small capacity system ( The power supply / demand balance of the small capacity system can be recovered in a short time, and the frequency of the small capacity system can be recovered in a short time.

  Therefore, when viewed from the large capacity system side, stable operation can be performed without being affected by disturbances such as load fluctuations in the small capacity system. On the other hand, when viewed from the small capacity system side, although some frequency fluctuations occur, the rotational speed control by the governor of the generator in the system is performed, so the frequency does not deviate greatly and is generally necessary. Therefore, it is not necessary to pay an extra cost related to the ancillary service for maintaining the excessive quality for the large-capacity system side, so that the power cost can be reduced.

  According to the present invention, the amount of power passing through the interconnecting means connected in series to the interconnecting point is detected, and the interconnecting means is controlled to equalize the detected value and the command value given separately. Even if the power supply / demand balance fluctuates in the capacity system, the impact on the large capacity system side is minimized, thereby maintaining the power quality on the large capacity system side and maintaining the power quality on the small capacity system side to the required level. Thus, it is possible to provide a power system interconnection system and a power control method capable of reducing costs.

  Hereinafter, a plurality of embodiments for carrying out the present invention as described above will be sequentially described with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the same part as the prior art shown in FIG.

[First Embodiment]
FIG. 1 is a block diagram showing a configuration of a power system interconnection system according to a first embodiment to which the present invention is applied. As shown in FIG. 1, the point that the power detector 140 detects the power interchange amount at the connection point 130 between the large capacity system 110 and the small capacity system 120 is the same as in the prior art. In the present embodiment, in addition to this configuration, an interconnection device (interconnection means) 150 that adjusts the amount of power accommodation is connected in series to the interconnection point 130, and the amount of power accommodation that passes through this interconnection device 150 is reduced. The power detector 140 is configured to detect the power, and an adder 160 and a control device 170 are provided as control means for controlling the interconnection device 150. The power detector 140, the interconnection device 150, the adder 160, and the control device 170 constitute an interconnection system S in a narrow sense.

  Here, the adder 160 receives the power accommodation amount detected value detected by the power detector 140 and a constant power accommodation amount command value given separately, extracts the difference, and outputs the obtained difference. It is configured as follows. Further, the control device 170 inputs a difference between the power accommodation amount detection value and the power accommodation amount command value from the adder 160, generates a control output signal for making this difference zero, and connects the interconnection device 150 to the interconnection device 150. Configured to control.

  That is, in the present embodiment, the interconnection device 150 is controlled by the amount of power that passes through the interconnection device 150 connected in series to the interconnection point 130, and passes through the interconnection point 130 as in the prior art. The output control of the generators 121 and 122 in the small capacity system 120 is not performed according to the power accommodation amount. In this embodiment, the generators 121 and 122 in the small-capacity system 120 are generally used as a governor for controlling the rotational speed of the generator to finely adjust and stabilize the power generation output. It is a powerful generator.

  In FIG. 1, only two generators 121 and 122 are shown as generators in the small capacity system 120 from the viewpoint of simplifying the explanation. Most of them include a generator. Similarly, only three loads L1 to L3 are shown as loads in the small-capacity system 120, but in reality, most of the loads include more loads than that.

  FIG. 2 shows the result of the power control operation realized by the interconnection system S of FIG. 1 as described above and the amount of power passing through the interconnection point 130 being controlled to be constant as a result of the operation. It is a flowchart which shows roughly the operation | movement performed by the generators 121 and 122 of.

As shown in FIG. 2, when a power accommodation amount detection value is detected by the power detector 140 (S201: power detection processing), the obtained power accommodation amount detection value is converted to a constant power accommodation amount by the adder 160. It is matched with the quantity command value, and the difference is extracted and output (S202: difference extraction process). Next, the control device 170 generates and outputs a control output signal for making the difference between the power accommodation amount detection value and the power accommodation amount command value zero (S203: control signal generation processing).
). The interconnection device 150 is controlled by this control output signal so that the difference between the power accommodation amount detection value and the power accommodation amount command value is zero, that is, the power accommodation amount passing through the interconnection device 150 is constant. By operating so as to become the power accommodation amount command value, the power accommodation amount is adjusted (S204: power adjustment processing).

  A series of processes (S201 to S204) from the detection process to the power adjustment process is performed every 30 seconds, every minute, etc. during operation of the interconnection system S (NO in S205). The power interchange amount that is continuously repeated at predetermined time intervals and passes through the interconnection device 150 at the interconnection point 130 is always controlled to a constant command value.

  When the load in the small capacity system 120 fluctuates in the state where the power accommodation amount passing through the interconnection point 130 is continuously monitored and controlled in this way, the power supply and demand balance in the small capacity system 120 is disrupted. In this case, since the power interchange amount passing through the interconnection point 130 is controlled to a constant command value, the frequency of the small capacity system temporarily changes (YES in S211). In this case, in the present embodiment, the rotational speed control operation by the governor of the generators 121 and 122 in the small capacity system 120 is performed, and thereby the power generation output is gradually adjusted (increase or decrease). The power supply / demand balance of the small capacity system is recovered in a short time, and the frequency of the small capacity system is recovered in a short time (S212). Such a series of operations (S211 and S212) is repeatedly performed while the generator is operating (NO in S213).

  For example, when the load in the small-capacity system 120 increases, the power interchange amount supplied from the large-capacity system 110 through the interconnection point 130 is controlled to a constant command value. Will decline. In this case, since the generators 121 and 122 in the small capacity system 120 gradually increase the power generation output by the rotational speed control operation by the governor, the power supply / demand balance of the small capacity system 120 is reached after several seconds to several tens of seconds. The frequency is recovered. The frequency drop width and the period during which the frequency is reduced in the small capacity system 120 is increased to some extent as compared with the conventional example. On the other hand, the large capacity system 110 side is not affected at all.

  According to the present embodiment as described above, the following effects are obtained on the large capacity system 110 side and the small capacity system 120 side, respectively. First, when viewed from the large capacity system 110 side, stable operation can be performed without being affected by disturbances such as load fluctuations in the small capacity system 120.

  On the other hand, when viewed from the small-capacity system 120 side, although some frequency fluctuations occur, the rotational speed control operation by the governor of the generators 121 and 122 in the system is performed, so the frequency does not deviate greatly. Since generally required power quality can be maintained, the system can be operated without any problem unless the load in the system is susceptible to frequency fluctuations. In addition, since it is not a method of controlling the power generation output of the generator in the small capacity system by the power accommodation amount passing through the interconnection point as in the past, an ancillary for maintaining the excess quality for the large capacity system side. Since it is not necessary to pay extra costs for the rally service, the power cost can be reduced. Therefore, on the small-capacity system 120 side, the cost can be reduced while maintaining the necessary power quality, and cheaper power can be obtained compared to the conventional one.

[Second Embodiment]
FIG. 3 is a block diagram showing a configuration of a power system interconnection system according to a second embodiment to which the present invention is applied. As shown in FIG. 3, this embodiment is a modification of the first embodiment, and when the large capacity system 110 and the small capacity system 120 are connected by a plurality of interconnection points 130a and 130b, Individual interconnection systems Sa and Sb similar to those of the first embodiment are provided at the interconnection points 130a and 130b, respectively.

  The interconnection systems Sa and Sb of the interconnection points 130a and 130b are set so that the individual power accommodation amounts passing through the interconnection points 130a and 130b are equal to the given power accommodation amount command values given to the interconnection points 130a and 130b. Control the amount of power interchange. Note that FIG. 3 shows a case where there are two interconnection points from the viewpoint of simplifying the description, but the same configuration can be made even when there are a large number of three or more interconnection points.

  According to the present embodiment having the above-described configuration, as in the first embodiment, each power interchange amount supplied from the large-capacity system 110 through the interconnection points 130a and 130b is set to a predetermined command. The value can be controlled. Therefore, even when the power supply / demand balance in the small capacity system 120 is lost and the frequency fluctuates, the generators 121 and 122 in the small capacity system 120 are controlled by the speed governor in the same manner as in the first embodiment. To restore power supply and demand balance and frequency. Therefore, according to the present embodiment, even when the large-capacity system 110 and the small-capacity system 120 are interconnected at a plurality of interconnecting points, the same effect as in the first embodiment can be obtained.

[Third Embodiment]
FIG. 4 is a block diagram showing a configuration of a power system interconnection system according to a third embodiment to which the present invention is applied. As shown in FIG. 4, the present embodiment is a modification of the first embodiment. In addition to the configuration of the interconnection system S in the first embodiment, the present embodiment corresponds to the frequency on the small capacity system 120 side. As a configuration for outputting a power accommodation amount command value, a voltage detector 410, a frequency detector 420, and a power accommodation amount switching circuit 430 are provided.

  Here, the voltage detector 410 is a means for detecting the voltage on the small capacity system 120 side and supplying it to the frequency detector 420. The frequency detector 420 is means for detecting the voltage frequency of the small-capacity system 120 from the detected voltage, and providing the obtained frequency detection value f to the power accommodation amount switching circuit 430. The frequency detection of the present invention. Corresponds to means. Furthermore, the power accommodation amount switching circuit 430 is a means for selecting a power accommodation amount corresponding to the frequency as a command value and giving it to the adder 160, and corresponds to the power accommodation amount switching means of the present invention.

  FIG. 5 is a block diagram showing an internal configuration of power accommodation amount switching circuit 430 shown in FIG. As shown in FIG. 5, the power interchange amount switching circuit 430 includes a high level detector 511, a low level detector 512, a high level duration detection circuit 521, a low level duration detection circuit 522, a switch selection circuit 530, and a switch. Circuit 540, and the like. Details of each part of the power accommodation amount switching circuit 430 are as follows.

First, the high level detector 511 and the low level detector 512 each receive the frequency detection value f and compare it with a preset reference value, and when the predetermined condition regarding the reference value is satisfied, the “ON” ( (Frequency fluctuation detection signal) output means, which corresponds to the frequency fluctuation detection means of the present invention. That is, the high level detector 511 outputs “ON” (high level detection signal) output when the frequency detection value f is equal to or higher than a predetermined high level reference value f _H (f> f _H ). Become. Further, the low level detector 512 outputs “ON” (low level detection signal) when the frequency detection value f becomes equal to or lower than a predetermined low level reference value f _L (f <f _L ). .

Here, as the level reference values f _H and f _L , a large value is set as the frequency fluctuation of the power system, for example, 110% and 90% of the rated frequency. Then, the respective “ON” outputs from the high level detector 511 and the low level detector 512 are given to the high level duration detection circuit 521 and the low level duration detection circuit 522, respectively.

  The high level duration detection circuit 521 and the low level duration detection circuit 522 are “ON” (change continuation detection) when the outputs from the level detectors 511 and 512 continue for a preset reference time T or more. Signal) output and corresponds to the variation continuation detecting means of the present invention. That is, the high level duration detection circuit 521 becomes an “ON” (high level continuation detection signal) output when the “ON” output from the high level detector 511 continues for the reference time T or more, and The low level duration detection circuit 522 becomes an “ON” (low level continuation detection signal) output when the “ON” output from the low level detector 512 continues for the reference time T or longer. Each “ON” output from the high level duration detection circuit 521 and the low level duration detection circuit 522 is given to the switch selection circuit 530.

  The switch selection circuit 530 provides a switching signal to the switch circuit 540 in accordance with each “ON” output from the high level duration detection circuit 521 and the low level duration detection circuit 522, and switches the terminals a to c. The switch circuit 540 is means for switching and outputting the power accommodation amount command value by switching the terminals a to c. These circuits 530 and 540 correspond to selection means of the present invention.

  In this case, as shown in FIG. 5, for example, the rated power “Po” of the interconnection device 150 is set to the terminal a of the switch circuit 540, and “Po × 0.5 (times) is set to the terminal b. ”And“ Po × 1.5 (times) ”are set in the terminal c. The switch selection circuit 530 outputs a switching signal for selecting the terminal b when the output of the high level duration detection circuit 521 is “ON” and when the output of the low level duration detection circuit 522 is “ON”. The switching signal for selecting the terminal c is supplied to the switch circuit 540, and in other cases, the switching signal for selecting the terminal a is supplied.

  FIG. 6 schematically shows the power control operation realized by the interconnection system S of FIG. 4 including the power accommodation amount switching circuit 430 of FIG. 5 as described above, mainly for the operation of switching the power accommodation amount command value. It is a flowchart. As shown in FIG. 6, in a steady state (YES in S601), the power accommodation amount switching circuit 430 holds the power accommodation amount command value at “Po” (S602). Then, through the series of processing shown in S201 to S204 in FIG. 2, the power accommodation amount accommodated from the large capacity system 110 to the small capacity system 120 is controlled to “Po” (S603).

Further, when the load amount in the small capacity system 120 fluctuates from the steady state and the power supply / demand balance is lost, the power interchange amount supplied from the large capacity system 110 through the connection point 130 is constant. Therefore, the frequency of the small-capacity system 120 varies. If the fluctuation range is within the range between the high level reference value and the low level reference value (f _L <f <f _H ) (NO in S604, NO in S605), the power interchange amount switching circuit 430 The accommodation amount command value is held at “Po” without being switched (S606). Therefore, as in the first embodiment, the power accommodation amount accommodated from the large-capacity system 110 to the small-capacity system 120 is controlled to the same “Po” as in the normal state (S201 to S204 in FIG. 2). The rotational speed control operation (S211 and S212 in FIG. 2) by the governor of the generators 121 and 122 in the small capacity system 120 is performed (S607).

On the other hand, when the load in the small-capacity system 120 is significantly increased, or when the generators 121 and 122 are stopped, the frequency is greatly reduced, and the frequency detection value f is lower than the low level reference value. (F <f _L ) (YES in S604). In this case, the low level detector 512 and the low level duration detection circuit 522 are turned “ON”, whereby the power interchange amount command value is switched to “Po × 1.5” (S608). After that, the power interchange amount supplied from the large capacity system 110 to the small capacity system 120 becomes 1.5 times that in the normal state, so that the frequency increases and the generators 121 and 122 in the small capacity system 120 are connected. Since the power generation output is finely adjusted by the rotational speed control operation by the governor, the power supply and demand balance in the small capacity system 120 is balanced and the frequency is restored after several seconds to several tens of seconds (S609).

On the other hand, when the load in the small capacity system 120 is greatly reduced, the frequency is greatly increased, and the frequency detection value f becomes equal to or higher than the high level reference value (f> f _H ) (YES in S605). . In this case, the high level detector 511 and the high level duration detection circuit 521 are turned “ON”, whereby the power interchange amount command value is switched to “Po × 0.5” (S610). Thereafter, the power interchange amount supplied from the large-capacity system 110 to the small-capacity system 120 becomes 0.5 times the normal value, so that the frequency decreases and the generators 121 and 122 in the small-capacity system 120 are connected. Since the power generation output is finely adjusted by the rotational speed control operation by the governor, the power supply and demand balance of the small capacity system 120 is balanced and the frequency is restored after several seconds to several tens of seconds (S611).

  Note that such a series of operations (S601 to S611) are repeatedly performed while the interconnection system S is being operated (NO in S612).

  According to the present embodiment as described above, the following effects are obtained on the large capacity system 110 side and the small capacity system 120 side, respectively. First, when viewed from the large-capacity system 110 side, a stable operation can be performed without being affected by disturbance due to a load fluctuation within a normal range in the small-capacity system 120. In addition, when a large disturbance such as a generator stop in the small capacity system 120 occurs, the power interchange amount changes. After the change, the interchangeable power amount is kept constant. In comparison, the effect is sufficiently small.

  On the other hand, when viewed from the small-capacity system 120 side, the frequency fluctuation is larger than that in the case of a load fluctuation within a normal range in the system, but the rotational speed control operation by the governor of the generator in the system is performed. Therefore, the frequency does not deviate greatly, and the power quality that is generally required can be maintained. Therefore, if the load in the system is not of a type that is susceptible to frequency fluctuations, it can be operated without problems. . In the case of a large disturbance exceeding the range that can be dealt with by changing the generator output in the small-capacity system 120 or by shutting off the load, such as stopping the generator in the small-capacity system 120, the power consumption from the large-capacity system 110 is reduced. The frequency fluctuation range can be suppressed by changing temporarily.

  Further, since it is not a method of controlling the power generation output of the generator in the small capacity system by the power accommodation amount passing through the interconnection point, as in the first embodiment, the excessive quality with respect to the large capacity system side. This eliminates the need to pay extra costs related to the ancillary service for maintaining the power consumption, thereby reducing the power cost. Therefore, on the small-capacity system 120 side, the cost can be reduced while maintaining the necessary power quality, and cheaper power can be obtained compared to the conventional one.

[Modification of Third Embodiment]
In addition, as a modification of 3rd Embodiment, although various forms are possible, For example, similarly to 2nd Embodiment with respect to the said 1st Embodiment, large capacity system | strain 110 and small capacity system | strain 120 are used. Even if there are a plurality of interconnection points, the same effect can be obtained. Alternatively, the interconnection system S of the third embodiment having the power accommodation amount switching circuit 430 is applied to one interconnection point among the plurality of interconnection points, and the electric power accommodation amount is set to the other interconnection points. It is also possible to apply the interconnection system S of the first embodiment that does not have the switching circuit 430.

  Further, depending on the system characteristics, in the power accommodation amount switching circuit 430 shown in FIG. 5, one set of the combinations of the level detectors 511 and 512 and the level duration detection circuits 521 and 522 can be omitted. For example, if there is almost no possibility that the frequency will be significantly increased due to a sudden decrease in load, and only a reduction in the frequency when the generator is stopped can be considered, the high level detector 511 and the high level duration detection circuit 521 are provided. Can be omitted.

[Fourth Embodiment]
FIG. 7 is a block diagram showing a configuration of a power system interconnection system according to a fourth embodiment to which the present invention is applied. As shown in FIG. 7, this embodiment is a modification of the first embodiment, and uses a rotary phase adjuster (RPS) 710 as the interconnection device 150 in the first embodiment. is there.

  Here, the armature (stator) of the rotary phase adjuster 710 is connected to the large capacity system 110 side, and the rotor (rotor) is connected to the small capacity system 120 side. Further, the rotary phase adjuster 710 is coaxially mounted with a torque control device 720 for driving the rotor at a variable speed, and the control device 170 controls the torque control device 720 by a control output signal. The rotary phase adjuster 710 is indirectly controlled. The configuration of the other parts is the same as that of the first embodiment.

  According to the present embodiment having the above-described configuration, the rotary phase adjuster 710 drives the rotor at a variable speed by the torque control device 720 that is attached coaxially, thereby increasing the magnitude of the voltage at the connection end. Since the phase and the frequency can be controlled, as shown in FIG. 7, by connecting in series to the interconnection point 130 of the two systems 110 and 120, the power interchange amount passing through the interconnection point 130 can be reduced. Can be controlled. Further, the frequency and phase on the armature side and the rotor side can be operated independently.

  Therefore, also in the present embodiment, the same effect as in the first embodiment can be obtained. Furthermore, since the rotary phase adjuster 710 is structurally resistant to overload operation, it is easy to accommodate more than rated power for a certain period of time, and during that time, the power supply-demand balance is restored on the small capacity system 120 side. System operation can be performed.

[Modification of Fourth Embodiment]
The rotary phase adjuster according to the fourth embodiment having the advantages as described above is particularly only when a large disturbance such as a generator stop of the small capacity system 120 occurs as in the third embodiment. It is suitable as an interconnection device of the interconnection system S that accommodates larger electric power than usual, and an excellent effect can be obtained. Various other forms are possible as modifications of the fourth embodiment. For example, as in the second embodiment relative to the first embodiment, the large capacity system 110 and the small capacity Even if there are a plurality of interconnection points of the system 120, the same effect can be obtained.

[Fifth Embodiment]
FIG. 8 is a block diagram showing a configuration of a power system interconnection system according to a fifth embodiment to which the present invention is applied. As shown in FIG. 8, the present embodiment is a modification of the first embodiment, and uses a DC interconnection device 810 as the interconnection device 150 in the first embodiment.

  Here, the DC interconnection device 810 includes AC / DC converters 811 and 812 and a DC circuit 813 that connects the AC / DC converters 811 and 812. One AC / DC converter 811 is connected to the large-capacity system 110 side and the other AC / DC converter 812 is connected. Are respectively connected to the small capacity system 120 side. Further, a pulse control device 820 is provided for applying ON / OFF pulses to the semiconductor elements of the AC / DC converters 811 and 812, and the control device 170 controls the pulse control device 820 with a control output signal, so The interconnection device 810 is indirectly controlled. The configuration of the other parts is the same as that of the first embodiment.

  According to the present embodiment having the above-described configuration, the DC interconnection device 810 temporarily converts AC power into DC power by using one AC / DC converter 811 and converts the DC power to AC by using the other AC / DC converter 812. By converting to electric power, electric power is accommodated. Since the AC sides of both converters 811 and 812 are independent, their frequency and phase are independent. Therefore, also in the present embodiment, the same effect as in the first embodiment can be obtained.

[Modification of Fifth Embodiment]
In addition, as a modification of the fifth embodiment, various forms are possible. For example, as in the second embodiment with respect to the first embodiment, the large-capacity system 110 and the small-capacity system 120 Even if there are a plurality of interconnection points, the same effect can be obtained. In addition, as in the third embodiment, the DC interconnection is used as an interconnection device of the interconnection system S that accommodates a larger amount of power than in a normal state only when a large disturbance such as a generator stop of the small capacity system 120 occurs. Even if the device 810 is applied, an equivalent effect can be obtained.

[Other Embodiments]
The present invention is not limited to the above-described embodiments, and various other modifications can be implemented within the scope of the present invention. That is, the system configuration, processing procedure, and the like shown in the embodiment are merely examples, and the specific system configuration, processing procedure, and the like can be freely selected.

The block diagram which shows the structure of the interconnection system of the electric power grid | system which concerns on 1st Embodiment to which this invention is applied. The flowchart which shows roughly the electric power control operation | movement implement | achieved by the interconnection system of FIG. 1, and the operation | movement performed by the generator of a small capacity | capacitance system as a result of this electric power control. The block diagram which shows the structure of the interconnection system of the electric power grid | system which concerns on 2nd Embodiment to which this invention is applied. The block diagram which shows the structure of the interconnection system of the electric power grid | system which concerns on 3rd Embodiment to which this invention is applied. The block diagram which shows the internal structure of the electric power accommodation amount switching circuit shown in FIG. The flowchart which shows roughly the electric power control operation | movement implement | achieved by the interconnection system shown in FIG. The block diagram which shows the structure of the interconnection system of the electric power grid | system which concerns on 4th Embodiment to which this invention is applied. The block diagram which shows the structure of the interconnection system of the electric power grid | system which concerns on 5th Embodiment to which this invention is applied. The block diagram which shows the structural example of the interconnection system of the conventional electric power system.

Explanation of symbols

S, Sa, Sb ... interconnection system 110 ... large capacity system 120 ... small capacity system 121, 122 ... generators 130, 130a, 130b ... interconnection point 140 ... power detector 150 ... interconnection device 160 ... control device 170 ... Adder 410 ... Voltage detector 420 ... Frequency detector 430 ... Power interchange amount switching circuit 511 ... High level detector 512 ... Low level detector 521 ... High level duration detection circuit 522 ... Low level duration detection circuit 530 ... Switch Selection circuit 540 ... switch circuit 710 ... rotary phase adjuster 720 ... torque control device 810 ... DC interconnection device 811, 812 ... AC / DC converter 813 ... DC circuit 820 ... pulse control device

Claims (8)

In a power system interconnection system that connects a small capacity power system with a smaller capacity to a large capacity power system,
Interconnecting means for adjusting power accommodation amount connected in series to an interconnection point connecting the large capacity and small capacity power systems;
Power detection means for detecting the amount of power interchanged through the interconnection means;
A control means for controlling the interconnection means by generating a control output signal for making the power accommodation amount detected value detected by the power detection means equal to a separately provided power accommodation amount command value;
A power system interconnection system characterized by comprising: Frequency detection means for detecting the frequency of the small-capacity power system;
A power accommodation amount switching means for selecting and switching the power accommodation amount command value according to the frequency detection value detected by the frequency detection means;
The power system interconnection system according to claim 1, further comprising: The power accommodation amount switching means is:
Frequency fluctuation detection means for outputting a frequency fluctuation detection signal when the fluctuation of the frequency detection value is greater than or equal to a preset reference value;
A fluctuation continuation detecting means for outputting a fluctuation continuation detection signal when the frequency fluctuation detection signal continues for a preset reference time or more;
Selecting means for selecting the power accommodation amount command value according to the variation continuation detection signal;
The interconnection system of the electric power system according to claim 2. The frequency fluctuation detecting means uses a high level reference value and a low level reference value as the reference value, and outputs a high level detection signal as the frequency fluctuation detection signal when the frequency detection value is equal to or higher than the high level reference value. And, when the frequency detection value is equal to or lower than a low level reference value, is configured to output a low level detection signal as the frequency fluctuation detection signal,
The fluctuation continuation detecting means outputs a high level continuation detection signal as the fluctuation continuation detection signal when the high level detection signal continues for the reference time or longer, and the low level detection signal continues for the reference time or longer. Configured to output a low level continuation detection signal as the fluctuation continuation detection signal when
The selection means, as the power accommodation amount command value, a first value according to the high level continuation detection signal, a second value according to the low level continuation detection signal, a third value in other cases, Configured to select one of a plurality of values including
The power system interconnection system according to claim 3. The interconnection means is a rotary phase adjuster,
The power system interconnection system according to any one of claims 1 to 4, wherein the system is a power system interconnection system. The interconnection means is a DC interconnection device,
The power system interconnection system according to any one of claims 1 to 4, wherein the system is a power system interconnection system. In the power control method of the power system for controlling the power flowing through the interconnection point connecting the small capacity power system with a smaller capacity to the large capacity power system,
Using interconnection means connected in series to the interconnection point to adjust the power accommodation amount,
A power detection step of detecting a power accommodation amount passing through the interconnection means;
Performing a control step of controlling the interconnection means by generating a control output signal for making the power accommodation amount detected value detected in the power detection step equal to a separately provided power accommodation amount command value;
A power control method for a power system. In the small-capacity power system, when the load in the system fluctuates, the power supply / demand balance in the system is disrupted, and the frequency of the small-capacity system once fluctuates, the speed regulator provided in the generator in the system The rotational speed control operation by the machine is performed, thereby gradually increasing or decreasing the power generation output, thereby restoring the power supply / demand balance of the system and restoring the frequency of the system.
The power control method for a power system according to claim 7.

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