JP7396131B2 - Distributed power source operation control device, distributed power source operation control method - Google Patents

Description

The present invention relates to a distributed power source operation control device and a distributed power source operation control method.

In recent years, power generation facilities (distributed power sources) that utilize renewable energy such as solar power generation and wind power generation have been interconnected to the power grid. The power generated by distributed power sources fluctuates depending on the renewable energy conditions (sunshine conditions in the case of solar power generation, wind power and wind direction conditions in the case of wind power generation, etc.). Therefore, in a power system in which distributed power sources are interconnected, power flow conditions change and voltage fluctuations occur as the power generation output of the distributed power sources changes. At this time, depending on the power generation output of the distributed power source and the value of the power factor set for the distributed power source, the voltage appearing in the power system may deviate from the predetermined voltage range, for example, There is a risk of malfunction.

As one method for controlling the operation of distributed power sources to solve such problems, for example, when the power generation output of a distributed power source is at its maximum, the power factor (ratio of active power to apparent power) is adjusted in advance. A constant power factor control method is known in which power factor is controlled to a predetermined constant value (for example, see Patent Document 1).

JP 2017-121163 Publication

However, when a distributed power source is connected to a power system that has large load current fluctuations over long distances, even if constant power factor control is applied to such a distributed power source, the voltage appearing in the power system cannot be adjusted in advance. It was difficult to maintain proper values within the defined voltage range.

Therefore, the present invention provides an operation control device for a distributed power source that is capable of suppressing voltage fluctuations in the power system even when the distributed power source is connected to a power system that has large load current fluctuations over long distances. and its operation control method.

The main invention for solving the above-mentioned problems is to reduce the phase difference between the positive-sequence voltage and the zero-sequence voltage at the exit point of the power source connected to the power system, and the positive phase difference at the point where the distributed power source is connected to the power system. Calculation of a phase difference angle that is a phase difference between a positive sequence voltage at an exit point of the power source and a positive sequence voltage at a connection point of the distributed power source, based on a phase difference between a phase voltage and a zero-sequence voltage. and a control unit that controls an operating state of the distributed power source based on the phase difference angle.
Other features of the invention will become apparent from the accompanying drawings and the description of this specification.

According to the present invention, even when a distributed power source is connected to a power system with large fluctuations in load current over a long distance, the power factor of the distributed power source can be controlled, for example, as one of the operational controls of the distributed power source. By appropriately setting it, it is possible to suppress voltage fluctuations in the power system.

FIG. 2 is a schematic diagram showing that distributed power sources are interconnected to a power system. FIG. 3 is a diagram for explaining a voltage phase difference angle between an exit point of a power source and a point where a distributed power source is connected. FIG. 3 is a diagram for explaining the relationship between the phase difference angle and the magnitude of load. It is a figure showing the relationship between phase difference angle and load. FIG. 3 is a diagram for explaining the relationship between the phase difference angle and the power generation output of a distributed power source. FIG. 3 is a diagram showing the relationship between phase difference angle, load size, and power generation output of a distributed power source. FIG. 1 is a diagram illustrating an example of an operation control device for a distributed power source according to the present embodiment. FIG. 2 is a diagram showing an example of table information stored in advance in a storage unit of the operation control device for a distributed power source according to the present embodiment. It is a flowchart which shows an example of operation of the operation control device of a distributed power supply concerning this embodiment.

From the description of this specification and the attached drawings, at least the following matters will become clear.
===Power system===
FIG. 1 is a schematic diagram showing that distributed power sources are interconnected with an electric power system.
In FIG. 1, a power system 100 includes a generator 200, a bus bar 300, a distribution line 400, and a distributed power source 500. Although the bus bar 300 and the distribution line 400 are actually three-phase, for convenience of explanation, they are shown as one line.

The generator 200 is a power source that supplies power to the power system 100, and is installed at a power plant, for example. The output of the generator 200 (the exit point of the power source) is connected to the bus 300.

The power distribution line 400 is connected to the bus bar 300 and is installed so as to extend toward the downstream side where power is supplied from the bus bar 300 so as to be able to supply power to a load 600 (consumer). Note that the power distribution line 400 shown as one is a set of three-phase power distribution lines, and a plurality of sets of power distribution lines 400 may be connected to the bus bar 300. In this case, the busbar 300 and the plurality of sets of distribution lines 400 form a bank within the power system 100.

Distributed power source 500 is a device that generates power using renewable energy. For example, examples of the distributed power source 500 include a wind power generation device that generates power using wind energy, a solar power generation device that generates power using solar energy, and the like. The distributed power source 500 is a device that generates electric power as a substitute for the electric power supplied from the generator 200 of a power plant, and is installed, for example, in a consumer's private home or on the premises of a factory. Here, if the power generated by the distributed power source 500 is less than the power consumed by the consumer, the customer needs to purchase power from the power grid 100, and on the other hand, the power generated by the distributed power source 500 is less than the power consumed by the consumer. If the surplus power exceeds the power consumed by the distributed power source 500, the surplus power of the distributed power source 500 will be sold via the power system 100. In order to perform these power purchases and power sales, the distributed power source 500 is connected to a power distribution line 400 and interconnected to the power system 100.

When the distributed power source 500 is connected to the power system 100, the power system 100 has a power flow from the upstream side to the downstream side of the distribution line 400, depending on the magnitude of the power generated by the distributed power source 500. Alternatively, a power flow in the opposite direction from the downstream side to the upstream side of the power distribution line 400 (reverse power flow) will occur. In this way, when the direction of the power flow in the power system 100 changes, the voltage appearing on the power distribution line 400 fluctuates. As a method to keep this voltage fluctuation within a certain voltage range, a constant power factor control method is adopted in which the power factor is set to a constant value when the power generation output of the distributed power source 500 reaches the maximum, as explained earlier. can do. However, if the length of the distribution line 400 branching from the busbar 300 is long, and the load current in the load 600 connected to this distribution line 400 fluctuates greatly, Even if a constant power factor control method is adopted for the distributed power source 500, it is currently difficult to maintain the voltage appearing on the distribution line 400 within a constant voltage range.

Furthermore, on the side of the distributed power source 500, it is difficult to grasp changes in the load on the distribution line 400 due to changes in the load on the distribution line 400 or the amount of power generated by other distributed power sources. Therefore, it is difficult to operate the distributed power source 500 in an optimal state depending on the system status. Note that the load on the distribution line 400 indicates the difference between the load supplied from the distribution line 400 and the amount of power generated by other distributed power sources.

Therefore, when a load 600 with large fluctuations in load current is connected to a long-distance distribution line 400, a distributed power source 500 is connected to this distribution line 400 to connect the distributed power source 500 to the power system 100. It is desired to stably suppress fluctuations in the voltage appearing on the power distribution line 400 when the system is connected to the power distribution line 400.

=== Phase difference angle at the point where bus bar 300 and distributed power source 500 are connected ===
<<Relationship between positive sequence voltage and zero sequence voltage of bus bar 300>>
For example, the relationship between the positive-sequence voltage V _s and the zero-sequence voltage V ₀ appearing at the bus bar 300, which is the output point (the exit point of the power source) of the generator 200 installed in a power plant, will be described below.

The zero-sequence voltage V ₀ appearing in the power system 100 can be determined, for example, by measuring the neutral point voltage of the ground-to-ground capacitance for three phases in the power system 100. This zero-phase voltage V ₀ is generated as a large value due to unbalance of the ground-to-ground capacitance of the three phases due to a ground fault or the like. For example, when a ground fault occurs, the zero-sequence voltage _V0 ranges from several volts to several tens of volts, but when no ground fault occurs, it is generally recognized as no voltage. The value is small, ranging from several mV to several tens of mV. Here, the ground-to-ground capacity of each phase is the sum of all the ground-to-ground capacities in the power system 100, so no matter where in the power system 100, there is an imbalance in the ground-to-ground capacity for the three phases. remains unchanged. Further, the unbalance of the ground-to-ground capacity for the three phases is hardly affected by fluctuations in the load 600 or fluctuations in the power generation output of the distributed power source 500. Therefore, the zero-phase voltage V ₀ exhibits substantially the same phase everywhere in the power system 100, regardless of the load 600 or the distributed power source 500. In other words, a constant phase difference α is generated between the positive-sequence voltage V _s and the zero-sequence voltage V ₀ at the bus bar 300 in the power plant.

<<Relationship between positive-sequence voltage and zero-sequence voltage of distributed power source 500>>
The zero-sequence voltage V ₀ appearing at the connection point of the distributed power source 500 to the distribution line 400 can be determined by connecting capacitors of the same capacity to each phase of the distribution line 400 and measuring the voltage between the neutral point and ground. It is determined by This zero-phase voltage V ₀ is the same as the zero-phase voltage V ₀ at the bus bar 300, and exhibits the same phase. Note that the zero-phase voltage V ₀ can be determined using, for example, a zero-phase voltage detector ZPD, but instead, it can also be determined by measuring the current of the three-phase sheath earth of the distribution line 400. . In other words, any means other than the zero-phase voltage detector ZPD may be used as long as it is capable of determining the zero-phase voltage _V0 .

The positive sequence voltage V _r appearing at the connection point of the distributed power source 500 to the distribution line 400 can be determined using, for example, a voltage transformer VT.

In this manner, when the positive-sequence voltage V _r of the distributed power source 500 is determined, the phase difference φ between the positive-sequence voltage V _r and the zero-sequence voltage V ₀ is also determined.

Since the zero-sequence voltage V ₀ is the same throughout the power system 100, the phase difference α between the positive-sequence voltage V _s and the zero-sequence voltage V ₀ at the bus bar 300 and the connection point of the distributed power source 500 to the distribution line 400 Using the phase difference φ between the positive _- sequence voltage V _{r and} the zero-sequence voltage V ₀ at The phase difference angle σ, which is the phase difference of , can be determined.

<<Phase difference angle at the point where bus bar 300 and distributed power source 500 are connected>>
Hereinafter, a specific example of the phase difference angle σ will be described with reference to FIG.
FIG. 2A shows an example where the phase of the zero-sequence voltage V ₀ is ahead of the phase of the positive-sequence voltages V _s and V _r . FIG. 2B shows an example in which the phase of the zero-sequence voltage V ₀ lags behind the phase of the positive-sequence voltage V _s and leads the phase of the positive-sequence voltage V _r . FIG. 2C shows an example where the phase of the zero-sequence voltage V ₀ lags behind the phases of the positive-sequence voltages V _s and V _r . For convenience of explanation, it is assumed in FIG. 2 that the size of the load 600 and the power generation output of the distributed power source 500 are constant. Further, the counterclockwise direction on the paper is defined as a phase leading direction (+), and the clockwise direction on the paper is defined as a phase lag direction (-).

Since the phase of the zero-sequence voltage _V0 is the same for the generator 200 and the distributed power source 500, the phase difference angle σ is determined from the phase difference α−phase difference φ, which is the difference between the phase difference α and the phase difference φ. be able to.

For example, in the case of FIG. 2(A), since the zero-sequence voltage V ₀ is ahead of the positive-sequence voltages V _s and V _r in phase, the phase difference α is included in the phase difference φ. , by subtracting the phase difference φ from the phase difference α (α−(+φ)), the positive-sequence voltage V _s and the positive-sequence voltage V which is on the opposite side from the zero-sequence voltage V ₀ with the positive-sequence voltage V _s as the boundary The phase difference angle σ between r and _r is determined. In addition, in the case of FIG. 2(B), since the phase of the zero-sequence voltage V ₀ is between the phase of the positive-sequence voltage V _s and the phase of the positive-sequence voltage V _s , the angle overlapping the phase differences α and φ is Instead, by subtracting the phase difference φ from the phase difference α (−α−(+φ)), the phase difference angle σ between the positive-sequence voltages V _s and V _r sandwiching the zero-sequence voltage V ₀ can be found. In addition, in the case of FIG. 2(C), since the zero-sequence voltage V ₀ is delayed in phase from the positive-sequence voltages V _s and V _r , the phase difference φ is included in the phase difference α. , by subtracting the phase difference φ from the phase difference α (-α-(-φ)), the positive-sequence voltage V _r and the positive phase that is opposite to the zero-sequence voltage V ₀ with the positive-sequence voltage V _r as the boundary The phase difference angle σ between the voltage V s and the voltage V _s is determined.

<<Relationship between phase difference angle and load>>
The relationship between the phase difference angle σ and the magnitude of the load 600 will be described below with reference to FIG.
FIG. 3(A) is a characteristic diagram for explaining the relationship between the phase difference α between the positive-sequence voltage V _s and the zero-sequence voltage V ₀ on the distribution line 400 and time when the load 600 is a heavy load. be. Moreover, FIG. 3(B) shows a characteristic for explaining the relationship between the phase difference α between the positive-sequence voltage V _s and the zero-sequence voltage V ₀ on the distribution line 400 and time when the load 600 is a light load. It is a diagram. Note that in FIGS. 3A and 3B, the horizontal axis represents time (msec), and the vertical axis represents voltage (kV). In addition, in FIGS. 3A and 3B, for example, three voltage curves (a solid line, a broken line, and a one-dot chain line) are drawn, respectively. It is assumed that the positive sequence voltage V _s appears at points X1 to X3 set in order in the direction of distance.

In both FIGS. 3A and 3B, the amplitude of the positive sequence voltage V _s (sine wave) gradually decreases as it moves from point X1 to point X3 (as it moves away from the bus line 300), and the period of the positive sequence voltage V _s It can be seen that it gradually becomes longer. Here, the phase difference α between the positive-sequence voltage V _s and the zero-sequence voltage V ₀ when the load 600 is a heavy load is the difference between the positive-sequence voltage V _s and the zero-sequence voltage V ₀ when the load 600 is a light load. It can be seen that the phase difference α is larger than the phase difference α. This difference is noticeable at point X3 on distribution line 400, which is farthest from busbar 300 and closest to the connection point of distributed power source 500. From this, the phase difference angle σ, which is the phase difference between the positive sequence voltage V _s of the generator 200 and the positive sequence voltage V _r of the distributed power source 500, increases as the load 600 becomes heavier and as the load 600 becomes lighter. You can see that it becomes smaller.

Here, in the power system 100 of FIG. 1, the positive sequence voltage V _s at the output point of the generator 200 which is the power transmission end of the power system 100, and the positive sequence voltage V r of the distributed power source 500 which is the power reception end of the power system 100 _. , the impedance X of the power distribution line 400 (however, for convenience of explanation, the resistance component of the electric circuit in the power system 100 is assumed to be 0), and the phase difference angle σ, the effective power P _r at the receiving end is calculated by the formula (1). It is shown as follows.

P _r = (V _s V _r /X) sin σ...(1)
The phase difference α is a constant value between the zero-sequence voltage V ₀ generated due to the unbalance of the ground-to-ground capacity of each phase of the distribution line 400 in the power system 100 and the positive-sequence voltage V _s at the output point of the generator 200. is the angle of On the other hand, the following equation (2) holds true between the phase difference φ between the positive-sequence voltage V _r and the zero-sequence voltage V ₀ of the distributed power source 500 and the phase difference angle σ.

σ=α±φ...(2)
However, φ is set to 0 when it is in the same phase as α.
Therefore, assuming that the load 600 is L, L is expressed by the following equation (3).
L=sinσ/( _X / _VsVr )...(3)

Equation (3) is an equation that omits the resistance of the electric circuit in the power system 100, but in the normal operation range of the power system 100, σ is within the range of 0 to 30 degrees, so is represented as a straight line. In other words, the load 600 and the phase difference angle σ have a substantially proportional relationship. This relationship is shown in FIG. The horizontal axis in FIG. 4 shows the magnitude of the load, and the vertical axis shows the phase difference angle. This also shows that the phase difference angle σ changes substantially like a linear function depending on the magnitude of the load 600.

<<Relationship between phase difference angle and power generation output of distributed power source 500>>
The relationship between the phase difference angle σ and the power generation output of the distributed power source 500 will be described with reference to FIG. 5.
FIG. 5(A) shows a characteristic for explaining the relationship between the phase difference α between the positive-sequence voltage V _s and the zero-sequence voltage V ₀ on the distribution line 400 and time when there is no power generation output of the distributed power source 500. It is a diagram. Further, FIG. 5(B) is for explaining the relationship between the phase difference α between the positive-sequence voltage V _s and the zero-sequence voltage V ₀ on the distribution line 400 and time when there is a power generation output of the distributed power source 500. FIG. Note that in FIGS. 5A and 5B, the horizontal axis represents time (msec), and the vertical axis represents voltage (kV). Furthermore, in FIGS. 5A and 5B, for example, three voltage curves (a solid line, a broken line, and a one-dot chain line) are drawn, respectively. It shows the positive-sequence voltage V _s that appears at points X1 to X3 set in order in the direction of distance.

In both FIGS. 5A and 5B, the amplitude of the positive-sequence voltage V _s (sine wave) gradually decreases as it moves from point X1 to point X3 (as it moves away from the bus line 300), and the period of the positive-sequence voltage V _s It can be seen that it gradually becomes longer. Here, the phase difference α between the positive-sequence voltage V _s and the zero-sequence voltage V ₀ when there is no power generation output of the distributed power source 500 is the difference between the positive-sequence voltage V _s and zero when there is a power generation output of the distributed power source 500. It can be seen that the phase difference α with respect to the phase voltage V ₀ is larger. This difference is noticeable at point X3 on distribution line 400, which is farthest from busbar 300 and closest to the connection point of distributed power source 500. From this, the phase difference angle σ, which is the phase difference between the positive-sequence voltage V _s of the generator 200 and the positive-sequence voltage V _r of the distributed power source 500, is substantially linear depending on the power generation output of the distributed power source 500. You can see that it changes like a function.

Here, in the power system 100 of FIG. 1, consider a case where the load 600 is connected to the distribution line 400 at an intermediate point between the generator 200 and the distributed power source 500. For example, when the power generation output of the distributed power source 500 gradually increases from 0, the phase difference angle σ, which was opened on the phase lag side due to the load 600, gradually becomes smaller. Then, when the power generation output of the distributed power source 500 becomes 1/2 of the power to be supplied to the load 600, the phase difference angle σ=0 (same phase). In this way, during the period until the phase difference angle σ, which was opened on the phase lag side due to the load 600, becomes 0, the direction in which power is supplied in the distribution line 400 is from the generator 200 side to the distributed power source 500 side. side (current). Furthermore, when the power generation output of the distributed power source 500 becomes larger than 1/2 of the power to be supplied to the load 600, the phase difference angle σ becomes wider on the phase leading side. At this time, the direction in which power is supplied in the distribution line 400 is from the distributed power source 500 side to the generator 200 side (reverse power flow).

The relationship among the phase difference angle σ, the size of the load 600, and the power generation output of the distributed power source 500, which has been explained above, can be expressed as a three-dimensional characteristic diagram, for example, as shown in FIG. 6. In other words, the phase difference angle σ is calculated by associating the magnitude of the load 600 and the generated output of the distributed power source 500 with a linear function relationship. It is determined as a value that three-dimensionally corresponds to .

===Operation control device of distributed power source 500===
Hereinafter, as an example of the operation control of the distributed power source 500, an operation control device that sets the power factor will be described with reference to FIG. 7.

FIG. 7 is a diagram showing an example of an operation control device for the distributed power source 500 according to the present embodiment.
The operation control device 700 of the distributed power source 500 controls the phase difference, which is the phase difference between the positive sequence voltage V _s of the bus bar 300, which is the output point of the generator 200, and the positive sequence voltage V _r of the distributed power source 500 in a normal state. The angle σ is calculated, and the value of the power factor of the distributed power source 500 is set according to the value of the phase difference angle σ so that voltage fluctuations in the distribution line 400 can be suppressed within a predetermined voltage range. It is a device that does Note that on the side of the distributed power source 500, since it is not possible to grasp the phase difference α between the positive-sequence voltage V _s and the zero-sequence voltage V ₀ at the output point of the generator 200, a preset value as a constant is set as α. We will use it.

The operation control device 700 includes a first calculation section 720, a second calculation section 730, a control section 740, and a storage section 750 as means for setting the power factor value of the distributed power source 500 as described above. has been done. Note that the operation control device 700 is configured to include, for example, a microcomputer, and its functions are realized by software processing based on a program for the microcomputer. The operation control device 700 may be provided integrally inside the distributed power source 500 or may be provided adjacent to the outside of the distributed power source 500.

The first calculation unit 720 calculates the phase difference φ between the positive-sequence voltage V _r and the zero-sequence voltage V ₀ appearing on the side of the distributed power source 500 connected to the distribution line 400 . The positive sequence voltage _Vr at the output point of the distributed power source 500 is measured, for example, by a voltage transformer VT (not shown), and information indicating the measured positive sequence voltage _Vr is supplied to the first calculation unit 720. Ru. Furthermore, the zero-sequence voltage V ₀ at the output point of the distributed power source 500 is determined by connecting capacitors of the same capacity to each phase of the distribution line 400 at the output point of the distributed power source 500, and connecting the capacitors between the neutral point and ground. The voltage is measured by, for example, a zero-phase voltage detector ZPD, and information indicating the measured zero-phase voltage V ₀ is supplied to the first calculation unit 720 . Then, the first calculation unit 720 calculates the phase difference φ from the supplied information on the positive-sequence voltage V _r and the zero-sequence voltage V ₀ .

Here, at all times when no ground fault occurs, the zero-sequence voltage V ₀ detected by the zero-sequence voltage detector ZPD on the output side of the distributed power source 500 is a fairly small value of several mV to several tens of mV. Therefore, in general consumers with many harmonic generation sources or at the installation point of the distributed power supply 500, the zero-sequence voltage V ₀ may be buried in harmonic noise, and there is a risk that the zero-sequence voltage V ₀ cannot be detected correctly. . Therefore, a filter 760 such as a band pass filter or a low pass filter is provided to remove harmonic noise from the zero phase voltage _V0 detected by the zero phase voltage detector ZPD. This filter 760 may be provided to remove similar high-frequency noise from the positive-sequence voltage _Vr of the distributed power source 500.

Here, in the zero-sequence voltage detector ZPD, since the capacitance connected between each phase and the ground is relatively small, it is possible to remove more high-frequency noise when detecting the zero-sequence voltage _V0 . A high-performance filter is required. Therefore, for example, an active filter can be used as the filter 760 that functions as a band-pass filter or a low-pass filter. An active filter is a circuit constructed by combining active elements such as operational amplifiers and transistors with resistors and capacitors. Compared to passive filters, it has an amplification function and has improved roll-off characteristics (attenuation slope). Since it has the following advantages, it is suitable for use as the filter 760.

The second calculation unit 730 calculates the phase difference angle σ as shown in FIG. 2 from the phase difference α preset as a constant and the phase difference φ obtained by the first calculation unit 720.

The storage unit 750 stores in advance information, as shown in FIG. 6, that associates the phase difference angle σ, the size of the load 600, and the power generation output of the distributed power source 500, obtained through knowledge, experiments, etc. ing.

Then, when the phase difference angle σ is determined by the third calculation unit 730, the control unit 740 estimates the size of the load 600 from this phase difference angle σ according to equation (3). The load 600 is assigned to either a heavy load or a light load, for example. In other words, if the size of the load 600 estimated at this time is larger than the predetermined reference value, the load 600 is assigned to heavy load, and even if the size of the load 600 is smaller than the reference value, the load 600 is assigned to heavy load. For example, load 600 is assigned to light load. Then, by referring to the storage unit 750, the control unit 740 determines the voltage change when the distributed power source 500 is dropped (suddenly stopped) based on the size of the load 600 at this time and the generated output of the distributed power source 500. Find the power factor that makes the smallest value, and set this power factor in the distributed power source 500. This is because the distributed power source 500 is required to have no effect on the voltage on the power system 100 side even if the power generation output of the distributed power source 500 fluctuates. This is based on the idea of minimizing voltage fluctuations on the distributed power source side when the power generation output of the distributed power source 500 fluctuates by determining the power factor that causes the smallest voltage change.

FIG. 8 is a diagram showing an example of table information stored in advance in the storage unit 750 of the operation control device 700.

The power generation output of the distributed power source 500 is classified into five levels of power generation output (0 [kW], 500 [kW], 1000 [kW], 1500 [kW], and 2000 [kW]), for example. For example, the load 600 is classified into heavy load and light load based on the above-mentioned reference value for each of the five levels of power generation output of the distributed power source 500. The power factor is classified into six levels of power factors (0.95, 0.94, 0.93, 0.92, 0.91, 0.90), for example.

The distributed power source 500 before the distributed power source 500 is disconnected is connected between one power generation output of the distributed power source 500, the load 600 (heavy load/light load), and one power factor. The positive sequence voltage V _r at the point, the positive sequence voltage V _r at the point where the distributed power source 500 is connected after the distributed power source 500 is disconnected, and the positive sequence voltage V r at the point where the distributed power source 500 is connected before and after the distributed power source 500 is disconnected. and the difference voltage between the positive sequence voltage _Vr at the point where the positive sequence voltage V r is stored in association with each other in the storage unit 750 .

For example, if the power generation output of the distributed power source 500 is 500 [kW], the load 600 is a heavy load, and the power factor of the distributed power source 500 is 0.95, the distributed power source 500 before the distributed power source 500 is disconnected is connected. The positive sequence voltage V _r at the point where the distributed power source 500 is connected is 6356 [V], and the positive sequence voltage V _r at the point where the distributed power source 500 is connected after the distributed power source 500 is disconnected is 6257 [V]. The difference voltage between the positive sequence voltage _Vr at the point where the distributed power source 500 is connected before and after the disconnection is -99 [V], which is stored in the storage unit 750. In addition, the black triangle shown in the differential voltage column in the figure indicates that the positive-sequence voltage V _r at the point where the distributed power source 500 was connected decreased after the distributed power source 500 was disconnected.

The table information shown in FIG. 8 includes the power generation output of the distributed power source 500, the load 600 (heavy load/light load), and the power generation output of the distributed power source 500 when the power generation output of the distributed power source 500 is other than 0 [kW]. There are 48 combinations of the power factor and the power factor, which are stored in the storage unit 750. In addition, in the case where the load 600 is a heavy load or a light load, the combination that minimizes the voltage difference between the positive sequence voltage _Vr at the point where the distributed power source 500 is connected before and after the distributed power source 500 is connected is as described in the explanation. For convenience, it is surrounded by a thick line.

The control unit 740 determines the corresponding power generation output and load 600 (heavy load or light load) of the distributed power source 500 from the actually determined phase difference angle σ, and refers to the table information stored in the storage unit 750. At this time, find the power factor that minimizes the voltage difference between the positive sequence voltage _Vr at the point where the distributed power source 500 is connected before and after the distributed power source 500 is disconnected, and calculate the power factor for the distributed power source 500 by Outputs a power factor setting signal to set the power factor to the specified power factor. For example, if it is found from the phase difference angle σ that the power generation output of the distributed power source 500 is 500 [kW] and that the load 600 is a heavy load, six combinations are selected, and among these, the lowest difference voltage is -43 [V], and the power factor at this time is 0.90. Therefore, the control unit 740 outputs a power factor control signal for setting the power factor of the distributed power source 500 to 0.90.

===Example of operation control flow of distributed power source 500===
FIG. 9 is a flowchart showing an example of the operation control operation of the distributed power source 500 according to the present embodiment. For convenience of explanation, it is assumed that the power generation output of the distributed power source 500 is, for example, 1000 [kW].

First, the first calculation unit 720 calculates the phase difference φ, which is the difference between the positive-sequence voltage V _r and the zero-sequence voltage V ₀ of the distributed power source 500 (step S1).

Next, the second calculation unit 730 calculates the position of the positive-sequence voltage at the point where the bus 300 and the distributed power source 500 are connected, based on the phase difference α having a predetermined value and the phase difference φ calculated in step S1. A phase difference angle σ, which is a phase difference, is calculated (step S2).

Next, the control unit 740 estimates the size of the load 600 from the phase difference angle σ according to equation (3), and if the load 600 at this time is larger than the reference value, it is assigned to heavy load; If the load 600 is smaller than the reference value, the load is assigned to light load (step S3).

Next, the control unit 740 refers to the table information stored in the storage unit 750 and calculates the power generation output of the corresponding distributed power source 500, the load 600 (heavy load or light load), and the power factor of the distributed power source 500. Extract combinations (6 ways). In this case, the combinations surrounded by thick broken lines in FIG. 8 are the combinations to be extracted (step S4).

Next, the control unit 740 selects a combination that minimizes the voltage difference between the positive sequence voltage V _r at the point where the distributed power source 500 is connected before and after the distributed power source 500 is connected, from among the six extracted combinations. further extract. In this case, a combination is extracted in which the voltage difference between the positive sequence voltage V _r at the point where the distributed power source 500 is connected is the minimum (-49 [V]) before and after the distributed power source 500 is disconnected (step S5).

Next, the control unit 740 selects a power factor of 0.90 that corresponds to the combination extracted in step S5, and outputs a power factor setting signal for setting the power factor of the distributed power source 500 to 0.90. (Step S6).

By setting the power factor of distributed power source 500 in this manner, it is possible to suppress voltage fluctuations in distribution line 400 from deviating from a predetermined voltage range.

===Summary===
As explained above, the operation control device 700 of the distributed power source 500 according to the present embodiment controls the positive-sequence voltage V _s and the zero-sequence voltage V ₀ at the output point of the generator 200 in the power plant connected to the power system 100. at the output point of the generator 200 based on the phase difference α between the positive-sequence voltage V _r and the zero-sequence voltage V ₀ at the point where the distributed power source 500 is connected to the power system 100. A calculation unit (first calculation unit 720, second calculation unit 730) that calculates a phase difference angle σ, which is a phase difference between the positive sequence voltage V _s and the positive sequence voltage V _r at the connection point of the distributed power source 500; The control unit 740 controls the operating state of the distributed power source 500 based on σ.

In this embodiment, the control unit 740 controls the power factor of the distributed power source 500 based on the phase difference angle σ as the operational control of the distributed power source 500.

Specifically, the control unit 740 determines the phase difference angle σ and at least one of the power generation output of the distributed power source 500 and the size of the load 600 connected to the power system 100 to which the distributed power source is interconnected. The power factor of the distributed power source 500 is controlled based on the relationship.

More specifically, the control unit 740 controls the distributed power source 500 so that when the distributed power source 500 is disconnected, the fluctuation width of the positive sequence voltage V _r at the point where the distributed power source 500 is connected is minimized. Control the power factor of

As a result, even when the distributed power source 500 is connected to the power system 100 that has large load current fluctuations over a long distance, for example, the power factor of the distributed power source 500 can be controlled as one of the operation controls of the distributed power source 500. By appropriately setting as in this embodiment, it becomes possible to suppress voltage fluctuations in the power system 100 within a predetermined voltage range.

The operation control device 700 also includes a zero-sequence voltage detector (for example, ZPD) that detects the zero-sequence voltage V ₀ at the point where the distributed power source 500 is connected to the power system 100, and a zero-sequence voltage detector (for example, ZPD) that detects harmonic noise from the zero-sequence voltage V _0. It may further include a filter 760 for removing. As a result, harmonic noise included in the zero-sequence voltage V ₀ can be removed, making it possible to accurately set the power factor of the distributed power source 500 and, in turn, reducing voltage fluctuations in the power system 100 to a predetermined voltage. It becomes possible to suppress the noise more reliably within the range.

Note that the above embodiments are for facilitating understanding of the present invention, and are not intended to be interpreted as limiting the present invention. The present invention may be modified and improved without departing from the spirit thereof, and the present invention also includes equivalents thereof.

In the present embodiment, the operation control of the distributed power source 500 is disclosed in which the power factor is set to a value according to the phase difference angle σ, but the present invention is not limited thereto. For example, if the obtained phase difference angle σ exceeds a predetermined angle, it is determined that the possibility of step-out has increased, and control is performed to disconnect the distributed power source 500 from the power system 100. good.

100 Power system 200 Generator 300 Bus bar 400 Distribution line 500 Distributed power source 600 Load 700 Operation control device 720 First calculation section 730 Second calculation section 740 Control section 750 Storage section 760 Filter

Claims (9)

The phase difference between the positive-sequence voltage and the zero-sequence voltage at the exit point of the power source connected to the power system, and the phase difference between the positive-sequence voltage and the zero-sequence voltage at the point where the distributed power source is connected to the power system. , a calculation unit that calculates a phase difference angle that is a phase difference between a positive sequence voltage at an exit point of the power source and a positive sequence voltage at a connection point of the distributed power source, based on
a control unit that controls the operating state of the distributed power source based on the phase difference angle;
An operation control device for a distributed power source, characterized by comprising: The operation control device for a distributed power source according to claim 1, wherein the control unit controls a power factor of the distributed power source based on the phase difference angle. The control unit is based on the relationship between the phase difference angle and at least one of the power generation output of the distributed power source and the size of a load connected to the power system to which the distributed power source is interconnected. 3. The operation control device for a distributed power source according to claim 2, wherein the power factor of the distributed power source is controlled. The control unit controls the power factor of the distributed power source so that when the distributed power source is disconnected, a fluctuation width of the positive-sequence voltage at a connection point of the distributed power source is minimized. The operation control device for a distributed power source according to claim 3. a zero-sequence voltage detector that detects a zero-sequence voltage at a point where the distributed power source is connected to the power system;
a filter that removes harmonic noise from the zero-sequence voltage;
The operation control device for a distributed power source according to claim 1, further comprising the following. The phase difference between the positive-sequence voltage and the zero-sequence voltage at the exit point of the power source connected to the power system, and the phase difference between the positive-sequence voltage and the zero-sequence voltage at the point where the distributed power source is connected to the power system. A first step of calculating a phase difference angle, which is a phase difference between the positive sequence voltage at the exit point of the power source and the positive sequence voltage at the connection point of the distributed power source, based on ,
a second step of controlling the operating state of the distributed power source based on the phase difference angle;
A method for controlling the operation of a distributed power source, the method comprising: 7. The method for controlling operation of a distributed power source according to claim 6, wherein in the second step, a power factor of the distributed power source is controlled based on the phase difference angle. In the second step, based on the relationship between the phase difference angle and at least one of the power generation output of the distributed power source and the size of the load connected to the power system to which the distributed power source is interconnected. 8. The method for controlling operation of a distributed power source according to claim 7, further comprising controlling a power factor of the distributed power source. In the second step, the power factor of the distributed power source is controlled so that the fluctuation width of the positive sequence voltage at the connection point of the distributed power source is minimized when the distributed power source is disconnected. The method for controlling operation of a distributed power source according to claim 8.

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