WO2012128137A1

WO2012128137A1 - Voltage rise suppression device and distributed power supply interconnection system

Info

Publication number: WO2012128137A1
Application number: PCT/JP2012/056506
Authority: WO
Inventors: 大類正洋; 河▲崎▼吉則; 西村荘治; 羽田儀宏
Original assignee: 日新電機株式会社
Priority date: 2011-03-23
Filing date: 2012-03-14
Publication date: 2012-09-27
Also published as: JP5705606B2; JP2012200111A; CN103444040A

Abstract

The purpose of the invention is to reduce an inequality caused by a position where a facility having a distributed power supply is connected to a distribution system and allow the distributed power supply to output an appropriate phase-advanced reactive power by correctly calculating a control parameter without giving disturbance to the distribution system. A voltage rise suppression device (50) comprises: a fundamental wave voltage determination unit (54) for determining a fundamental wave voltage at an interconnection point (18); an operational power factor determination unit (56) for determining the operational power factor of a distributed power supply (30); a reactive power calculation unit (58) for calculating a first phase-advanced reactive power corresponding to the difference between the fundamental wave voltage and a voltage upper limit value; and an active power control unit (60) for reducing the active power output from the distributed power supply (30). The voltage rise suppression device (50) further comprises: a current injection unit (72) for injecting injection current (I_m) of non-integral multiple orders (m); a ratio calculation unit (62) for, using voltage and current having an injection order (m), calculating the resistance and reactance of the fundamental wave component of a distribution system and the ratio (α₁) of the former to the latter; a reactive power calculation unit (64) for calculating a second phase-advanced reactive power by multiplying the active power output from the distributed power supply (30), the ratio (α₁), and a correction coefficient (β) to each other; a total reactive power calculation unit (66) for calculating a total phase-advanced reactive power by adding the first and second phase-advanced reactive powers to each other; a limiting reactive power calculation unit (68) for, using the active power output from the distributed power supply (30) and a power factor lower limit value, calculating a limiting phase-advanced reactive power for obtaining the power factor lower limit value when the active power is output; and a reactive power control unit (70) for suppressing the total phase-advanced reactive power and supplying to the distributed power supply (30) as a phase-advanced reactive power command value.

Description

Voltage rise suppression device and distributed power interconnection system

The present invention relates to a voltage rise suppression device that controls a distributed power supply of a distributed power supply facility connected to a distribution system and suppresses a voltage increase of the distribution system. Furthermore, the present invention relates to a distributed power supply interconnection system in which a plurality of distributed power supply facilities each having the voltage rise suppression device are connected to a power distribution system.

For example, a distributed power supply facility having a distributed power source such as a photovoltaic power generation system (abbreviated as PV) and having a reverse power flow (that is, a flow of effective power from the distributed power source to the system side) is provided in the distribution system. Conventionally, a plurality of (for example, many) connections are used to form a distributed power supply interconnection system.

An example is shown in FIG. In this distributed power supply interconnection system, a distribution system 2 having a high-voltage distribution line 10, a transformer 14, and a low-voltage distribution line 16 is connected to the host system 1, and further, a distributed power supply (for example, FIG. A plurality of distributed power supply facilities 200 having a distributed power supply 202 in FIG. 4 are connected. A place where each of the distributed power supply facilities 200 is connected to the power distribution system 2 (in this example, the low voltage distribution line 16) is referred to as a connection point 18.

One of the main problems in such a distributed power supply interconnection system is that the voltage at the interconnection point 18 increases due to reverse power flow, and the voltage is a predetermined upper limit value (for example, 107 V) defined by the Electricity Business Law or the like. ).

Therefore, in order to suppress the above voltage increase, Non-Patent Document 1 proposes to provide a distributed power supply facility 200 with a voltage increase suppressing device having a function as shown in FIG. 2 (for example, page 99). reference).

This voltage rise suppression device measures a voltage (specifically, a fundamental wave voltage) at the interconnection point 18 (step 301), and determines whether or not the voltage is higher than a predetermined upper limit value (for example, 107V) ( Step 302). If it is higher, it is further determined whether or not the driving power factor is equal to or higher than a predetermined lower limit value (for example, 0.85) (step 303). The phase advance reactive power Q to be output is increased in accordance with the difference between the voltage and the upper limit value (step 304). If the operating power factor is smaller than the lower limit value, the distributed power supply of the own equipment is controlled and the active power P output therefrom is decreased according to the difference between the voltage and the upper limit value (step 305). As a result, the voltage at the interconnection point 18 can be suppressed to an upper limit value or less.

The main points of the principle are explained as follows. In this application, the active power flowing from the distributed power supply facility 200 (or 20, which will be described later, the same applies hereinafter) to the power distribution system 2 is P, and the phase reactive power is Q.

Assuming that the impedance of the distribution system 2 is r + jx (r is resistance, x is reactance, see FIG. 3 and the like), the voltage increase value ΔV due to the flow of the active power P and the phase reactive power Q is expressed by the following equation. . The impedance of the upper system 1 is much smaller than the impedance of the power distribution system 2, and is ignored in this application for the sake of simplicity.

[Equation 1]
ΔV = P · r−Q · x

Expressing this in terms of current, assuming that the effective current flowing from the distributed power supply facility 200 to the power distribution system 2 is I _p and the phase advance reactive power is I _q , the voltage increase value ΔV is expressed by the following equation.

[Equation 2]
ΔV = I _p · r−I _q · x

As can be seen from Equation 1, the voltage increase value ΔV can be reduced by increasing the fast reactive power Q (step 304) or decreasing the active power P (step 305). The voltage rise can be suppressed.

Note that the processing in steps 306 to 309 in FIG. 2 is performed when the voltage is equal to or lower than the upper limit value, and thus detailed description thereof is omitted here.

As another technique for suppressing the voltage increase at the interconnection point 18, Patent Document 1 and Non-Patent Document 2 describe a control parameter α represented by the number 3 of the distribution system 2 (that is, reactance of the resistance r of the distribution system 2). The ratio to x) is determined by measuring the change in voltage of the fundamental wave (for example, 60 Hz, the same applies hereinafter) at the interconnection point 18 due to the change in the output current, and using that, the output from the distributed power source holding facility 200 is calculated. A technique for controlling the phase reactive power Q so that it becomes Equation 4 is described (will be described in more detail later). In short, this equation 4 is equal to the equation 1 above where ΔV = 0.

[Equation 3]
α = r / x

[Equation 4]
Q = (r / x) P = α · P

Patent Document 2 and Non-Patent Document 3 will be referred to later.

JP 2006-158179 A (paragraphs 0008-0009, 0016) JP 2001-128366 A

When the plurality of distributed power supply facilities 200 are each provided with the voltage rise suppression device having the function described in Non-Patent Document 1, the position where the distributed power supply facilities 200 are connected to the distribution system (that is, the upstream side) Depending on whether it is downstream or not, regarding the power output from the distributed power supply of its own equipment, there is a difference in the amount of increase in the fast reactive power Q or the amount of decrease in the active power P necessary for suppressing voltage rise, resulting in inequality There are challenges. In this application, “upstream side” refers to the side closer to the upper system 1 (in other words, the system power supply, upper transformer), and “downstream side” refers to the opposite side.

Simply put, the voltage at the interconnection point 18 of the own equipment is added to the secondary voltage of the transformer 14 by adding the voltage increase value ΔV on the upstream side of the own equipment. This is because the voltage at the interconnection point 18 increases as it approaches the side end.

Therefore, since the downstream distributed power supply facility 200 is more likely to exceed the upper limit value in the upstream distributed power supply facility 200, the voltage at the connection point 18 is suppressed. In addition, it is necessary to output a large amount of the phase reactive power Q from the distributed power source in the own facility or to greatly reduce the active power P. Incidentally, since the phase advance reactive power Q increases the loss in the distributed power supply, the phase advance reactive power Q is limited from the viewpoint of power supply capacity.

Thus, it is unequal that the difference as described above occurs depending on the position where the distributed power supply facility 200 is connected to the power distribution system 2. For example, when the distributed power supply facility 200 sells power (sells the active power P to an electric power company), a difference occurs in the income from the power sale. In some cases, the voltage has already risen to the upper limit value on the upstream side of the own facility. In this case, no matter how hard the own facility works, the voltage at the interconnection point 18 cannot be suppressed below the upper limit value. Therefore, it is possible that almost no power can be sold.

For example, if the distributed power source is a solar power generation system, there is almost the same amount of solar radiation in the same region, and although almost the same amount of power can be generated, the power that can be used in the downstream distributed power source decreases and the utilization rate decreases. Can happen.

Since the technology described in Patent Literature 1 and Non-Patent Literature 2 outputs each phased reactive power Q in proportion to the active power P output from the own equipment, each of the distributed power source possessing equipment 200, roughly speaking, Although the problem of inequality occurrence like the technique described in Non-Patent Document 1 can be solved, there are the following problems with respect to obtaining the control parameter α.

The technique described in Patent Literature 1 artificially changes the active power (specifically, the fundamental wave active current) and the reactive power (specifically, the fundamental wave reactive current) output from its own equipment, and controls the control parameter α. Ask for. An outline of this principle will be described with reference to FIG.

Variation .DELTA.V _p of the fundamental wave voltage of the connecting point 18 due to the change [Delta] I _p of the fundamental wave active current I _p, the variation .DELTA.V _q of the fundamental wave voltage of the connecting point 18 due to the change [Delta] I _q of the fundamental wave reactive current I _q Has the following relationship: r and x are the resistance and reactance of the distribution system 2 described above, respectively.

[Equation 5]
δV _p = ΔI _p · r
δV _q = ΔI _q · x

Using both of these, the following equation is calculated to obtain the control parameter α _m .

[Equation 6]
α _m = (δV _p / ΔI _p ) / (δV _q / ΔI _q ) = r / x

Since the control parameter α _m = r / x calculated in this way is the same as the true control parameter α = r / x shown in Equation 3, the control parameter α can be correctly calculated by the above method. .

However, the technique described in Patent Document 1 has a problem that artificial disturbance is given to the fundamental wave power of the distribution system.

Although the technique described in Non-Patent Document 2 obtains the control parameter α based on substantially the same principle as described above, the active power (specifically, fundamental wave active current) and reactive power (specifically, output from the own equipment) Since the control parameter α is obtained by utilizing the natural variation of the fundamental wave reactive current), it is not necessary to give artificial disturbance to the distribution system. However, there are cases where the control parameter α cannot be calculated correctly. This will be described below.

As in the example illustrated in FIG. 4, when attention is paid to the distributed power source possessing facility 200a (which is referred to as the own facility 200a) adopting the technology described in Non-Patent Document 2, a normal (that is, the above-described) A case where a distributed power source possessing facility 200b (operating at a power factor of 100% as described in Non-Patent Document 1 page 29) is connected will be taken up. The capacity of both the

facilities

200a and 200b is assumed to be the same capacity here for the sake of simplicity. When the distributed power source 202 of both

facilities

200a and 200b is a solar power generation system, both solar power generation systems are similarly exposed to solar radiation, so that the effective currents I _p1 and I _p2 change in the same manner. That is, the change ΔI _p1 = ΔI _{p2 of} both. A change in reactive current of the own facility 200a is assumed to be ΔI _q1 .

Such a situation can generally occur not only in the solar power generation system but also in other renewable energy-based power generation such as adjacent wind power generation facilities. In addition, the possibility of such a situation is further increased when a mass interconnection to a power system of a renewable energy power source such as solar light, which is expected in the future, is realized.

In such a case, the change δV _p1 of the interconnection point voltage of the own facility 200a due to the change of the fundamental wave active current is expressed by the following equation. This is because ΔI _p2 = ΔI _p1 as described above.

[Equation 7]
δV _p1 = (Voltage increase due to ΔI _p2 ) + (Voltage increase due to ΔI _p1 )
= ΔI _p1 · r + ΔI _p1 · r
= ΔI _p1 · 2r

A change δV _q1 of the connection point voltage of the own facility 200a due to a change in the fundamental wave reactive current is expressed by the following equation.

[Equation 8]
δV _q1 = ΔI _q1 · x

Similar to the case of Equation 6, the following equation is calculated using δV _p1 and δV _q1 of

Equations

7 and 8, and the control parameter α _m is obtained.

[Equation 9]
α _m = (δV _p1 / ΔI _p1 ) / (δV _q1 / ΔI _q1 ) = 2 (r / x)

The control parameter α _m = 2 (r / x) calculated in this way is twice the true control parameter α = r / x shown in Equation 3. That is, in this case, the control parameter α cannot be calculated correctly.

Therefore, in this case, the own equipment 200a that employs the technique described in Non-Patent Document 2 performs twice the amount of the original power when performing the reactive power control (see Equation 4) Q = α · P. The phase reactive power Q is output, and an extra reactive power burden is borne. This causes various inconveniences. For example, the operating power factor of the distributed power source 202 in the own facility 200a is extremely deteriorated. If the amount of the phase advance reactive power Q cannot be output, the voltage increase value ΔV at the interconnection point 18 cannot be suppressed to a predetermined upper limit value (for example, 107 V) or less.

Even if the capacity of the nearby distributed power supply facility 200b is different from the capacity of the own facility 200a, an event similar to the above occurs.

Note that the technology described in Non-Patent Document 2 is actually a slightly modified version of the above principle, but the principle is the same, so a detailed description thereof is omitted here.

Therefore, the present invention can reduce inequalities due to the position where the distributed power supply facility is connected to the power distribution system in the voltage rise suppression control of the interconnection point, and control parameters without causing disturbance to the power distribution system. The main object is to provide a voltage rise suppression device capable of correctly calculating and outputting appropriate phase advance reactive power from a distributed power source.

The voltage rise suppression device according to the present invention is a voltage rise suppression device that controls a distributed power supply of a distributed power supply facility connected to a distribution system and suppresses a voltage increase of the distribution system,
Fundamental wave voltage determining means for determining whether a fundamental wave voltage at a connection point between the distribution system and the distributed power supply facility is higher than a predetermined voltage upper limit value;
Driving power factor determining means for determining whether or not the operating power factor of the distributed power source is equal to or higher than a predetermined power factor lower limit when the determination result in the fundamental wave voltage determining means is affirmative;
First reactive power calculation means for calculating and outputting a first phase reactive power according to a difference between the fundamental voltage and the voltage upper limit value when the determination result in the driving power factor determination means is affirmative When,
When the determination result by the driving power factor determination means is negative, the effective power that controls the distributed power source and outputs from the distributed power source is reduced according to the difference between the fundamental voltage and the voltage upper limit value. Power control means;
Current injection means for injecting an injection current of a non-integer multiple order of the fundamental wave of the power distribution system into the power distribution system;
Using the voltage and current of the injection order at the interconnection point, the fundamental wave component resistance (r ₁ ), reactance (x ₁ ) and ratio of the former to the latter (α ₁ = r ₁ / x ₁ ) Ratio calculating means for calculating
A second reactive power calculation means for calculating and outputting a second phase reactive power by multiplying the active power output from the distributed power source, the ratio, and a correction coefficient β of 0 <β <1;
Total reactive power calculation means for adding the first and second phase reactive power to each other to calculate and output a total phase reactive power;
Using the active power output from the distributed power source and the power factor lower limit value, limit reactive power calculation means for calculating limit advanced reactive power that realizes the power factor lower limit value at the time of the active power, and
The total advanced phase reactive power is supplied to the distributed power source as an advanced phase reactive power command value with the upper limit suppressed to the value of the limit advanced phase reactive power, and the advanced phase reactive power output from the distributed power source is Reactive power control means for controlling to a phase advance reactive power command value is provided.

The correction coefficient β may be set in the range of 0.5 to 0.8.

In the case of a distributed power interconnection system in which a plurality of distributed power supply holding facilities each having a voltage rise suppression device according to the present invention are connected to a secondary distribution line of the same transformer, between each voltage rise suppression device, It is preferable to make the injection orders different from each other or to make the injection and measurement timing different from each other.

According to the first aspect of the invention, the following effects can be obtained.

Using the ratio α ₁ corresponding to the control parameter α described above, the calculation of Q _b = α ₁ · β · P is performed to obtain the second advanced reactive power Q _b , which is used for the advanced reactive power control. Since it is used for a part, the control to output the second phase reactive power Q _b in proportion to the active power P output from the distributed power source of the own equipment is added to the phase reactive power control, Therefore, the occurrence of inequality as in the technique described in Non-Patent Document 1 can be reduced.

In order to obtain the ratio α ₁ , in the voltage rise suppressing device according to the present invention, an injection current having an injection order of a non-integer multiple of the fundamental wave, which does not naturally exist in the distribution system, is transferred from the current injection means to the distribution system. Since the injection is performed, the injection current may be small, so that the distribution system is not disturbed.

Since the ratio α ₁ is obtained by measuring the voltage and current of the injection order of the own equipment by the ratio calculation means, another distributed power source is provided near the own equipment having the voltage rise suppressing device according to the present invention. Even if owned facilities exist, for example, even if there are other distributed power owned facilities that perform 100% power factor operation as described above, the ratio α ₁ can be calculated correctly without being affected by it. it can. Even if another distributed power source possessing equipment having the voltage rise suppressing device according to the present invention exists near its own equipment, there are several countermeasures for it. For example, the injection order can be selected from a number of orders, unlike the only order (ie primary, eg 60 Hz) as in the case of the fundamental of the distribution system. It is easy to use different injection orders from each other, thereby eliminating the mutual interference and correctly calculating the ratio α ₁ . Therefore, in any case, appropriate phase advance reactive power can be output from the distributed power supply.

In addition, when a plurality of distributed power sources are connected to the distribution system, the system voltage increases due to the output (active power) of the other distributed power sources. Further, since the fast reactive power Q becomes smaller than the value of Q expressed by the above equation 4 due to the correction coefficient β of 0 <β <1, the system voltage also increases due to the output of the own equipment (active power P). Voltage rises due to these may be added, and an event may occur in which the fundamental voltage at the interconnection point of the own equipment exceeds a predetermined voltage upper limit value. In view of this, a means for determining the fundamental wave voltage at the interconnection point and the operating power factor of the distributed power source and controlling the increase in the first phase reactive power or the decrease in the active power is provided. Therefore, it is possible to prevent the fundamental wave voltage at the interconnection point from exceeding a predetermined voltage upper limit value. Further, it is possible to prevent the operating power factor of the distributed power source from falling below a predetermined power factor lower limit value. The means performs measurement and control by measuring the fundamental voltage and controlling the fundamental output current, and therefore does not interfere with the current injection and the voltage measurement for measuring the ratio α ₁ .

In addition, since the phase reactive power output from the distributed power supply is limited to the value of the critical phase reactive power, the operating power factor of the distributed power supply is reliably prevented from falling below a predetermined power factor lower limit value. can do.

The invention according to claim 2 has the following further effects. That is, since the correction coefficient β is set in the above range, the output amount of the second phase reactive power can be appropriately suppressed, and the decrease in the driving power factor can be reduced. Moreover, even in such a case, since the fundamental wave voltage at the interconnection point and the operating power factor of the distributed power source are determined, a means for controlling the increase in the first phase reactive power or the decrease in the active power is provided. It is possible to prevent the fundamental wave voltage at the interconnection point from exceeding a predetermined voltage upper limit value, or the operating power factor of the distributed power source from falling below a predetermined power factor lower limit value.

According to invention of Claim 3, in addition to the effect of invention of

Claim

1, 2, there exists the following further effect. That is, even when a plurality of distributed power source holding facilities each having the voltage rise suppression device according to

claim

1 or 2 are connected to a distribution line on the secondary side of the same transformer, the injection order to be used is the voltage of each facility. Since the increase suppression devices are different from each other, the above-mentioned ratio α ₁ can be correctly calculated without interference of the voltage increase suppression devices of the plurality of distributed power supply facilities. Therefore, appropriate phase advance reactive power can be output from each distributed power source.

According to invention of Claim 4, in addition to the effect of invention of

Claim

claim

1 or 2 are connected to a secondary distribution line of the same transformer, injection of injected current and its injection order The voltage and current measurement timings of the respective facilities are different from each other in the voltage increase suppressing device of each facility, so that the above-mentioned ratio α ₁ can be calculated correctly without interfering with the voltage increase suppressing devices of the plurality of distributed power supply owned facilities. . Therefore, appropriate phase advance reactive power can be output from each distributed power source.

It is a single line connection figure which shows an example of the conventional distributed power supply interconnection system with which the some distributed power supply possession equipment was connected to the power distribution system. 10 is a flowchart illustrating an example of a function of the voltage rise suppression device described in Non-Patent Document 1. It is a figure for demonstrating the prior art example of the method of measuring a fundamental wave voltage and a fundamental wave current, and calculating | requiring the control parameter (alpha). It is a figure for demonstrating the subject of the prior art example which measures a fundamental wave voltage and a fundamental wave current, and calculates | requires control parameter (alpha). 1 is a single line connection diagram illustrating an example of a distributed power interconnection system according to the present invention. It is a figure which shows an example of a structure of each distributed power supply equipment and the voltage rise suppression apparatus which comprises it. It is a flowchart which shows an example of operation | movement of the voltage rise suppression apparatus in FIG. It is a block diagram which shows an example of a structure of a fundamental wave voltage judgment part and a driving power factor judgment part. It is a block diagram which shows an example of a structure of a 1st reactive power calculating part. It is a block diagram which shows an example of a structure of an active power control part. It is a block diagram which shows an example of a structure of a ratio calculating part. It is a block diagram which shows an example of a structure of a 2nd reactive power calculating part, a total reactive power calculating part, a limit reactive power calculating part, and a reactive power control part. It is a figure which shows the other example of a structure of each distributed power supply possession installation and the voltage rise suppression apparatus which comprises it. It is a figure which shows the example in case a distributed power supply possession facility has the interconnection transformer for high voltage | pressure interconnection. It is a figure which shows the model of the distributed power supply interconnection system used for simulation. It is a figure which shows an example of the simulation result of a transformer near voltage and each interconnection point voltage when the conventional voltage rise suppression apparatus which has a function shown in FIG. 2 is used. It is a figure which shows an example of the simulation result of the active power output from each distributed power supply when using the conventional voltage rise suppression apparatus which has a function shown in FIG. 2, a phase reactive power, and a driving power factor. It is a figure which shows an example of the simulation result of a transformer near voltage and each interconnection point voltage when the voltage rise suppression apparatus (however, it was set as (beta) = 1) of the example shown in FIG. FIG. 7 is a diagram showing an example of simulation results of active power, phase reactive power, and driving power factor output from each distributed power source when using the voltage rise suppression device of the example shown in FIG. 6 (where β = 1). . It is a figure which shows an example of the simulation result of a transformer near voltage and each interconnection point voltage when the voltage rise suppression apparatus (however, it was set as (beta) = 0.5) of the example shown in FIG. The figure which shows an example of the simulation result of the active power output from each distributed power supply when using the voltage rise suppression apparatus of the example shown in FIG. It is. It is a figure which shows an example of the simulation result of a transformer near voltage and each interconnection point voltage when the conventional voltage rise suppression apparatus which has a function shown in FIG. 2 is used when resistance of a distribution line is large. An example of simulation results of active power, phase reactive power, and driving power factor output from each distributed power source when the conventional voltage rise suppression device having the function shown in FIG. 2 is used when the resistance of the distribution line is large FIG. The figure which shows an example of the simulation result of a transformer near voltage and each interconnection point voltage when the voltage rise suppression apparatus (however, it is set as (beta) = 1) of the example shown in FIG. 6 when resistance of a distribution line is large. It is. When the resistance of the distribution line is large, the active power, the fast reactive power, and the driving power factor output from each distributed power source when using the voltage rise suppression device of the example shown in FIG. 6 (where β = 1) are used. It is a figure which shows an example of a simulation result. An example of the simulation result of the voltage close to the transformer and each interconnection point voltage when using the voltage rise suppression device of the example shown in FIG. 6 (where β = 0.5) when the resistance of the distribution line is large FIG. When the resistance of the distribution line is large, the active power, the fast reactive power and the driving power output from each distributed power source when the voltage rise suppression device of the example shown in FIG. 6 (where β = 0.5) is used It is a figure which shows an example of the simulation result of a rate. It is a figure for demonstrating the voltage which generate | occur | produces in a connection point when injecting injection current into a power distribution system.

(1) One Embodiment of Voltage Increase Suppression Device 50 and Distributed Power Supply Interconnection System FIG. 5 shows an example of a distributed power supply interconnection system according to the present invention. In this distributed power supply interconnection system, a plurality of distributed power supply holding facilities 20 each having a distributed power supply (see the distributed power supply 30 in FIG. 6) are connected to the power distribution system 2 (in this embodiment, to the low voltage distribution line 16, the same applies hereinafter). It has a configuration. This connection point is called a connection point 18.

In this example, the distribution system 2 has a configuration in which a high-voltage distribution line 10 is connected to the higher-level system 1 and a low-voltage distribution line 16 is connected to the high-voltage distribution line 10 via a transformer 14.

A plurality of distributed power source holding facilities 20 are connected to the low voltage distribution line 16. To give a more specific example, a large number of low-voltage interconnection distributed power holding facilities 20 that have contracts with reverse power flow are connected at a high density (this is called low-voltage high-density interconnection). The transformer 14 is, for example, a 6600V / 200V single-phase three-wire pole transformer.

Each distributed power supply facility 20 is, for example, a power generation facility having a distributed power source, a home, a supermarket, a factory, or other facilities.

An example of the configuration of each distributed power supply facility 20 is shown in FIG. The distributed power source possessing facility 20 includes a distributed power source 30 connected to the interconnection point 18 and a voltage increase suppressing device 50 that controls the distributed power source 30. The voltage V _{d at the} interconnection point 18 is measured by the instrument transformer 40 and is given to the voltage rise suppression device 50. The current I _d flowing through the interconnection point 18 is measured by the instrument current transformer 42 and is given to the voltage rise suppression device 50.

In this embodiment, the distributed power supply 30 includes a solar cell 32 and an inverter (inverse conversion device) 34 that converts the output into AC power. That is, it is a photovoltaic power generation system (abbreviated as PV). However, the present invention is not limited to this, and other examples will be described later.

As the inverter 34, a known inverter (for example, refer to pages 16 to 17 of the non-patent document 1) can be used. Active power P and phase reactive power Q output from the inverter 34 can be controlled by external control signals (specifically, an active power command value P _com and a phase reactive power command value Q _com described later). The technique is publicly known (see, for example, Patent Document 2 above).

In this embodiment, the voltage rise suppressing device 50 includes a measuring unit 52, a fundamental wave voltage determining unit 54 constituting a fundamental wave voltage judging unit, a driving power factor judging unit 56 constituting a driving power factor judging unit, and a first invalidity. The first reactive power calculation unit 58 constituting the power calculation means, the active power control unit 60 constituting the active power control means, the ratio calculation unit 62 constituting the ratio calculation means, and the total reactive power constituting the total reactive power calculation means A calculation unit 66, a limit reactive power calculation unit 68 constituting limit reactive power calculation means, a reactive power control unit 70 constituting reactive power control means, and a current injection unit 72 constituting current injection means are provided. An example of the operation of the voltage rise suppressing device 50 is shown in FIG. 7, and the description of each control unit and the like will be given below with reference to this. A specific example of the configuration of each control unit will be described later.

The measuring unit 52 calculates the active power P output from the distributed power source 30 and the operating power factor Pf of the distributed power source 30 using the voltage V _d and the current I _d , and sends it to other control units that need it. A function of giving (steps 401 and 402). However, instead of providing the measurement unit 52 in a lump, another control unit that requires the active power P and the driving power factor Pf may have a function of calculating it.

The fundamental wave voltage determination unit 54 measures the fundamental wave voltage (voltage of the fundamental wave frequency (for example, 60 Hz) of the distribution system 2) at the interconnection point 18 of the own equipment (step 405), and this is a predetermined voltage upper limit value. It is determined whether the voltage is higher than (eg, 107 V) (step 406).

The driving power factor determination unit 56 determines whether or not the measured value of the driving power factor Pf of the distributed power source 30 is equal to or greater than a predetermined power factor lower limit value (for example, 0.85) when the determination result in the fundamental wave voltage determination unit 54 is positive. (Step 407).

The first reactive power calculation unit 58 calculates the first phase reactive power Q _a according to the difference between the fundamental voltage and the voltage upper limit value when the determination result in the driving power factor determination unit 56 is affirmative. Calculation and output (step 408).

When the determination result in the driving power factor determination unit 56 is negative, the active power control unit 60 controls the distributed power source 30 to output the active power P output from the distributed power source 30 as the fundamental voltage and the voltage upper limit value. (Step 409). Specifically, the active power command value P _com is given to the inverter 34 for control.

Current injection unit 72, a non-integer multiples of the fundamental wave of the distribution system 2 (i.e. bands decimal times) order m injected current I _m outputs to the power distribution it system 2 (specifically, the low-voltage distribution line 16) (Step 403). The injection order m is, for example, 2.2 order, 2.4 order, 2.6 order, 2.8 order, etc., but is not limited thereto.

When the injection current _Im is injected, a voltage V _{m of the} injection order _m is generated at the interconnection point 18 in proportion to the impedance Z _m of the injection order m of the distribution system 2 as shown in FIG. . This is included in the connection point voltage V _d . Ratio calculation unit 62, a voltage V _m and current I _m of the injection order m in its own equipment interconnection point 18 is measured, using the measurement results, the fundamental wave of the power distribution system 2 viewed from the connecting point 18 A ratio α ₁ expressed by the following equation is calculated (part of step 404) for the component resistance r ₁ , reactance x ₁ and the former latter.

[Equation 10]
α ₁ = r ₁ / x ₁

The second reactive power calculation unit 64 multiplies the measured value of the active power P output from the distributed power source 30 with the ratio α ₁ and the correction coefficient β of 0 <β <1, and is expressed by the following equation. the second phase advancing reactive power Q _b a and calculates and outputs (step 404) is intended.

[Equation 11]
Q _b = α ₁・ β ・ P

Note that the positions on the flowchart of

steps

403 and 404 are not necessarily limited to the positions shown in FIG. 7, and may be provided at other positions, for example, immediately before step 410. This is because it is only necessary to calculate the second phase advance reactive power Q _b before calculating the total phase advance reactive power Q _t in step 410.

The total reactive power calculation unit 66 adds the first advanced reactive power Q _a and the second advanced reactive power Q _b to each other to calculate a total advanced reactive power Q _t expressed by the following equation. Is output (step 410).

[Equation 12]
Q _t = Q _a + Q _b

The limit reactive power calculation unit 68 uses the measured value of the active power P output from the distributed power supply 30 and the power factor lower limit value to limit the phase advance invalidity that realizes the power factor lower limit value at the active power P. The power Q _lim is calculated and output (part of step 411).

The reactive power control unit 70 suppresses the upper limit of the total advanced reactive power Q _t to the value of the limit advanced reactive power Q _lim and uses it as the advanced reactive power command value Q _com as the distributed power supply 30 (specifically, Is supplied to the inverter 34), and the phase reactive power Q output from the distributed power source 30 is controlled to the phase reactive power command value Q _com (step 411).

Note that the processing in steps 413 to 416 in FIG. 7 corresponds to the processing in steps 306 to 309 in FIG. 2, and is performed when the fundamental wave voltage is equal to or lower than the upper limit value. Such processing functions are not essential to the present invention, and thus detailed description thereof is omitted here. In short, if the determination in step 406 is negative, the process may proceed to step 410.

Next, a specific example of the configuration of each control unit will be described.

As shown in FIG. 8, the fundamental voltage determination unit 54 includes a subtractor 80 and a comparator 82. The driving power factor determination unit 56 includes a comparator 84, a NOT circuit 86, and AND

circuits

88 and 89. In addition, although there are elements shared by a plurality of control units (for example, subtractor 80 and AND circuits 88 and 89), for convenience of explanation, one of the control units is configured below for the sake of convenience. It is described as a thing.

The subtracter 80 subtracts a voltage upper limit value V _lim (for example, 107 V ₎ from the voltage V _{d at the} interconnection point 18 and outputs a difference voltage DV expressed by the following equation. The voltage upper limit value V _lim is set and stored in the voltage rise suppression device 50. Since the harmonic voltage included in the voltage V _d is smaller than the fundamental voltage, the voltage V _d is used instead of the fundamental voltage in the following embodiments. .

[Equation 13]
DV = V _d −V _lim

The comparator 82 determines whether or not the differential voltage DV is greater than 0V (corresponding to step 406 in FIG. 7), and outputs a signal having a logical value of 1 when the difference voltage DV is greater than 0V. 88 and 89.

The comparator 84 determines whether or not the operating power factor Pf of the distributed power supply 30 of its own equipment is equal to or higher than the power factor lower limit value Pf _lim (for example, 0.85) (corresponding to step 407), and the power factor lower limit value Pf _lim. At this time, a signal having a logical value of 1 is output and applied to the AND circuit 88 and the NOT circuit 86. Therefore, when the determination in step 407 is Yes, a signal of logical value 1 is output from the AND circuit 88. The power factor lower limit value Pf _lim is set and stored in the voltage rise suppression device 50.

The NOT circuit 86 inverts the logical value of the signal from the comparator 84 and supplies it to the AND circuit 89. Therefore, when the determination in step 407 is No, the AND circuit 89 outputs a signal having a logical value of 1.

As shown in FIG. 9, the first reactive power calculation unit 58 includes a multiplier 90 and a PI control unit 91.

The multiplier 90 multiplies the difference voltage DV from the subtractor 80 and the signal from the AND circuit 88 and outputs the result. That is, when the signal output from the AND circuit 88 is a logical value 1, the difference voltage DV is output.

The PI control unit 91 multiplies the difference voltage DV from the multiplier 90 by coefficients K _p1 and K _i1 and outputs them, an integrator 94 that integrates and outputs the output from the amplifier 93, and this by adding the outputs of the amplifier 92 of the integrator 94 and an adder 95 to output as the first phase advancing reactive power Q _a. For example, K _p1 = 2 × 10 ¹⁴ and K _i1 = 4 × 10 ⁵ , but not limited thereto.

As shown in FIG. 10, the active power control unit 60 includes a multiplier 96, a PI control unit 97, and a subtracter 102.

The multiplier 96 multiplies the difference voltage DV from the subtractor 80 and the signal from the AND circuit 89 and outputs the result. That is, when the signal output from the AND circuit 89 is a logical value 1, the difference voltage DV is output.

The PI control unit 97 multiplies the difference voltage DV from the multiplier 96 by the coefficients K _p2 and K _i2 and outputs them, an integrator 100 that integrates and outputs the output from the amplifier 99, and this An adder 101 that adds the output of the integrator 100 and the output of the amplifier 98 to output the effective power reduction amount P _dn is provided. For example, K _p2 = 2 × 10 ¹³ and K _i2 = 4 × 10 ⁴ , but not limited thereto.

The subtracter 102 subtracts the effective power decrease amount P _dn from the maximum active power output P _max of the distributed power supply 30 of its own equipment (that is, the maximum active power that can be output when there is no active power suppression), and The active power command value P _com represented is output. More specifically, this active power command value P _{com is given} to the distributed power source 30 (specifically, to the inverter 34), and the active power P output from the distributed power source 30 is controlled to that value.

[Formula 14]
P _com = P _max -P _dn

When the distributed power source 30 is a solar power generation system, the inverter 34 usually controls the output voltage of the solar cell 32 so that the effective power output from the solar cell 32 is maximized (this is (Abbreviated as P _max control). When the distributed power source 30 is a photovoltaic power generation system, it can be said that the active power by the P _max control is the maximum active power output P _max .

11, the ratio calculation unit 62 includes

discrete Fourier transformers

104 and 105, a divider 106, a separator 108, an amplifier 110, and a divider 112.

The

discrete Fourier transformers

104 and 105 perform discrete Fourier transform on the voltage V _d and current I _d (both vector quantities) of the interconnection point, respectively, and the voltage V _{m of the} injection order m at the interconnection point 18 of the own equipment. , Current I _m (both vector quantities) are extracted and output.

The divider 106 divides the following equation to calculate and output the impedance Z _m (vector quantity) of the injection order m of the power distribution system 2 as viewed from the interconnection point 18 of its own equipment.

[Equation 15]
Z _m = V _m / I _m

Referring also to FIG. 28, the impedance Z _m can be expressed by the following equation, where r _{m is} the resistance of the injection order m of the distribution system 2 viewed from the interconnection point 18 of the own equipment, and x _m is reactance. .

[Equation 16]
Z _m = r _m + jx _m

Therefore, the separator 108 separates the real part (resistance component) and the imaginary part (reactance component) from the calculation result of Equation 15, and outputs the resistance r _m and reactance x _m of the injection order m separately. Since the resistance does not depend on the frequency, the resistance r _m is equal to the resistance r ₁ of the fundamental wave component.

The amplifier 110 multiplies the reactance x _m by 1 / m (in other words, divides the reactance x _m by the injection order m), and calculates and outputs the reactance x ₁ of the fundamental wave component.

The divider 112 performs the calculation shown in Equation 10 above using the resistance r ₁ and reactance x ₁ of the fundamental wave component, and outputs the ratio α ₁ . Incidentally, by providing the averaging filter at the output of the divider 112, through which may be output ratio alpha _1.

As shown in FIG. 12, the second reactive power calculation unit 64 includes an amplifier 114 and a multiplier 116.

The amplifier 114 multiplies the ratio α ₁ from the ratio calculator 62 by the correction coefficient β and outputs α ₁ · β.

Multiplier 116 multiplies active power P output from its own distributed power supply 30 and α ₁ · β to calculate and output second phase reactive power Q _b shown in Equation 11 above. .

The total reactive power calculation unit 66 is an adder, and calculates the first advanced phase reactive power Q _a given from the reactive power computation unit 58 and the second advanced phase reactive power Q _b given from the multiplier 116. By adding together, the total advanced reactive power Q _t shown in the above _{equation 12} is calculated and output.

The limit reactive power calculation unit 68 calculates the following equation using the active power P and the power factor lower limit value Pf _lim , and outputs the limit advanced reactive power Q _lim . For example, when the power factor lower limit value Pf _lim = 0.85, the calculation of Q _lim = 0.62P is performed. At this time, the limit reactive power calculation unit 68 may be a simple amplifier.

[Equation 17]
Q _lim = tan {cos ⁻¹ (Pf _lim )} · P

The reactive power control unit 70 suppresses the total advanced reactive power Q _t given from the total reactive power computing unit 66 to the value of the critical advanced reactive power Q _lim given by the limit reactive power computing unit 68. Thus, a limiter circuit that outputs the phase advance reactive power command value Q _com is provided. Then, the phase reactive power command value Q _com is supplied to the distributed power supply 30 (specifically, the inverter 34) of its own equipment, and the phase reactive power Q output from the distributed power supply 30 is converted into the phase advanced reactive power command value. Control to Q _com .

As the current injection unit 72, a known current injection device, for example, a current injection device as described in Non-Patent Document 3 can be used.

Further, instead of providing the current injection unit 72 independently, the inverter 34 may have the same function as the current injection unit 72 so that the inverter 34 also serves as the current injection unit 72. For outputting the harmonic current together with the fundamental wave power from the inverter, for example, a known technique as described in Patent Document 2 can be used.

The effect of using this voltage rise suppression device 50 is as follows.

(A) The coefficient α ₁ corresponds to the control parameter α described above. In this voltage rise suppression device 50, using the ratio α ₁ , the calculation of Q _b = α ₁ · β · P is performed to obtain the second advanced reactive power Q _b , which is used for advanced reactive power control. Therefore, control for outputting the second phase reactive power Q _b in proportion to the active power P output from the distributed power source 30 of the own facility 20 is added to the phase reactive power control. Accordingly, it is possible to reduce the occurrence of inequality due to the position connected to the power distribution system 2 as in the technique described in Non-Patent Document 1.

This will be described in more detail. As described above, when the voltage rise suppressing device having the function described in Non-Patent Document 1 is used, the upstream distributed power source possessing facility 200 is connected to the interconnection point 18 of its own facility. Since the voltage rise value ΔV of V is small, it is not necessary to output the phase-advanced reactive power Q so much (in the opposite case, the reverse case), but when this voltage rise suppression device 50 is used, it is used. All the distributed power supply facilities 20 are proportional to the active power P of their own equipment regardless of the voltage rise value ΔV of the interconnection point 18 of the own equipment, in other words, regardless of the position connected to the distribution system 2. thereby outputting phase lead reactive power Q in consideration of the above second phase advancing reactive power Q _b. With this second phase advance reactive power Q _b , all the distributed power supply facilities 20 having this voltage rise suppression device 50 can cooperate to suppress the voltage rise. The first phase advance reactive power Q _a is the same as in the case of the technique described in Non-Patent Document 1, but the voltage rise suppression device 50 uses the second phase advance reactive power for the phase advance reactive power control. Considering Q _b , the above-described inequality caused by the position connected to the power distribution system 2 can be reduced.

(B) to determine the ratio alpha _1, in the voltage increase suppressing device 50, does not exist almost spontaneously distribution system 2, current injection the injection current I _m of the injection order m of non-integer multiple orders of the fundamental wave Since the power is injected from the section 72 into the power distribution system 2, the injection current _Im may be small, so that the power distribution system 2 is not disturbed.

In more detail, as described in Non-Patent Document 3 (see, for example, the right column on page 994 (58)), the voltage of the non-integer multiple order component naturally existing in the distribution system 2 is the basic voltage. 0.01% or less of the wave components, in the voltage increase suppressing device 50 may be implanted injection current I _m to generate a voltage V _m to the extent that can be distinguished from this voltage. For example, if the low-voltage distribution line 16 is 200V system, it may be implanted injection current I _m of about 0.4 A. As a result, the voltage V _m of the injection order m appearing at the interconnection point 18 becomes about 0.04 V (0.02%). With recent measurement techniques, this level of voltage V _m can be measured sufficiently. Even if such an injection current _Im is injected, the distribution system 2 is not disturbed.

By (c) a ratio calculation unit 62, so by measuring the voltage V _m and current I _m of the injection order m of the own equipment 20 obtains the ratio alpha _1, the self equipment having the voltage rise suppression unit 50 Even if there is another distributed power supply facility near 20, for example, there is another distributed power supply facility that performs 100% power factor operation (see the distributed power supply facility 200 b in FIG. 4). However, the ratio α ₁ can be calculated correctly without being affected by the above. This is because, as described above, the voltage V _m of the injection order m naturally does not substantially exist. This is because the other distributed power supply facility (200b) does not inject an injection current of the injection order m. Therefore, it is possible to output appropriate phase advance reactive power Q from the distributed power supply 30.

Even if another distributed power source possessing facility 20 having this voltage rise suppression device 50 exists near the own facility 20, there are several countermeasures for it. For example, the injection order m can be selected from a number of orders, unlike the only order (ie, first order, for example, 60 Hz) as in the case of the fundamental wave of the distribution system 2. It is easy to make the injection orders m used by other equipment different from each other, thereby eliminating the mutual interference and correctly calculating the ratio α ₁ . Further, as will be described later, when a transformer is interposed, the large impedance is interposed, so that mutual interference can be eliminated even in the case of the same injection order m. Accordingly, in this case as well, an appropriate phase advance reactive power Q can be output from the distributed power source 30.

As orders of the injection current I _m, as described in Patent Document 2, an integral multiple orders of the fundamental wave of the distribution system 2 (e.g., 2, fourth, fifth, etc.) be used are not preferred . This is because there are a number of harmonic sources of integer multiple orders at various locations in the power distribution system 2, so that it is difficult to accurately measure the voltage of the order injected by the own equipment. In addition, since the number of integer multiple orders that can be practically used is limited, the injection orders used by the own equipment and other equipment are the same, and mutual interference is likely to occur.

(D) When a plurality of distributed power sources are connected to the distribution system 2, the system voltage rises due to the output (active power) of the other distributed power sources. Further, because the phase advance reactive power Q becomes smaller than the value of Q expressed by the above equation 4 due to the correction coefficient β of 0 <β <1, the system voltage also increases due to the output of the own facility 20 (active power P). . An increase in voltage due to these may be added, and an event may occur in which the fundamental voltage at the interconnection point 18 of the own facility 20 exceeds a predetermined voltage upper limit value. In view of this, the voltage rise suppression device 50 further determines the fundamental wave voltage at the interconnection point 18 and the operating power factor Pf of the distributed power source 30 to determine the first phase reactive power Q _a . Since it includes means for controlling increase or decrease of active power P (fundamental wave voltage determination unit 54, driving power factor determination unit 56, first reactive power calculation unit 58 and active power control unit 60), the connection point It is possible to prevent the 18 fundamental wave voltages from exceeding a predetermined voltage upper limit value V _lim . Further, it is possible to prevent the operating power factor Pf of the distributed power source 30 from falling below a predetermined power factor lower limit value Pf _lim . The means performs measurement and control by measuring the fundamental voltage and controlling the fundamental output current, and therefore does not interfere with the current injection and the voltage measurement for measuring the ratio α ₁ .

(E) The voltage rise suppression device 50 limits the phase advance reactive power Q output from the distributed power supply 30 to the value of the limit advance reactive power Q _lim (limit reactive power calculation unit 68 and reactive power control unit 70). Therefore, it is possible to reliably prevent the operating power factor Pf of the distributed power source 30 from falling below a predetermined power factor lower limit value Pf _lim .

When the correction coefficient β is increased, the second phase reactive power Q _b increases and the operating power factor Pf of the distributed power source 30 may decrease. If the correction coefficient β is decreased, the second phase reactive power Q _b is decreased, and the effect of suppressing the occurrence of inequality may be reduced. Therefore, the correction coefficient β is more preferably in the range of 0.5 to 0.8 even when 0 <β <1. The reason for deriving this will be described below.

The ratio α ₁ (= r / x) of the general low-voltage distribution system 2 is approximately 0.7 to 1.1. The operating power factor Pf of the distributed power source 30 in this α ₁ range is 0.67 to 0.82 from the following equation.

[Equation 18]
Pf = tan ⁻¹ (Q / P) = tan ⁻¹ α ₁

As described in Non-Patent Document 1 (see page 96, for example), when the lower limit of the driving power factor Pf is 0.85, the ratio α _{1 at} that time is 0.62.

Therefore, the range of the correction coefficient β that multiplies the ratio α ₁ in the above range by the correction coefficient β to make the driving power factor Pf 0.85 or more is expressed by the following equation.

[Equation 19]
(0.62 / 1.1) <β <(0.62 / 0.7)
∴0.56 <β <0.89

Increasing the correction coefficient β has a great effect on reducing the output inequality, but for the purpose of preventing a decrease in the driving power factor Pf as much as possible, an intermediate value of 0.8 in the range of Equation 19 is set to be a correction coefficient. It is preferable to set the upper limit of β. From the simulation results described below, it has been confirmed that even if the lower limit of the correction coefficient β is 0.5, it is effective in suppressing voltage rise. Therefore, the correction coefficient β is preferably in the range of 0.5 to 0.8.

When the correction coefficient β is set in the above range, the output of the second phase advancing reactive power Q _b moderately suppressed, it is possible to reduce the decrease in the operating power factor Pf. Moreover Even so, to determine the fundamental wave voltage and the operating power factor of the distributed power 30 Pf interconnection node 18, means for controlling the increase or decrease of the active power P of the first phase advancing reactive power Q _a (Fundamental wave voltage judgment unit 54, driving power factor judgment unit 56, first reactive power calculation unit 58 and active power control unit 60), the fundamental wave voltage at interconnection point 18 is a predetermined voltage upper limit value. It is possible to prevent V _lim from being exceeded or the operating power factor Pf of the distributed power source 30 to fall below a predetermined power factor lower limit value Pf _lim .

(2) Other Embodiments of Voltage Rise Suppression Device 50 and Distributed Power Supply Interconnection System As in the example shown in FIG. 5, a plurality of distributed power source possessing facilities 20 each having the voltage rise suppression device 50 are the same transformer. In the case of a distributed power interconnection system connected to the secondary distribution line (in the example of FIG. 5, the secondary low voltage distribution line 16 of the same transformer 14, the same applies hereinafter), for example, each voltage rise suppression device 50 Preferably, the injection current Im of the non-integer multiple order and different orders _m is injected, and the voltage and current of the injection order m are measured. For example, the injection order m is set to different orders such as 2.2 order, 2.4 order, 2.6 order, 2.8 order, etc.

If it does so, even if the some distributed power supply possession equipment 20 which each has the said voltage rise suppression apparatus 50 is connected to the distribution line of the secondary side of the same transformer, the injection order m to be used is the voltage rise of each equipment. Since the suppression devices 50 are different from each other, the above-mentioned ratio α ₁ can be calculated correctly without the voltage increase suppression devices 50 of the plurality of distributed power supply equipment 20 interfering with each other. Therefore, appropriate phase advance reactive power Q can be output from each distributed power supply 30.

If it is not the secondary side of the same transformer, a transformer will be interposed between them, and a large impedance of the transformer will be interposed. Therefore, it is not necessary to make the injection orders m different from each other as described above. In addition, it is possible to prevent the voltage rise suppression devices 50 of the plurality of distributed power source holding facilities 20 from interfering with each other.

Alternatively, when the plurality of distributed power supply holding facilities 20 each having the voltage increase suppression device 50 is a distributed power supply interconnection system connected to a secondary distribution line of the same transformer, each voltage increase suppression device 50 is the non-integral multiple a order injecting the injection current I _m of the same order m from each other and shall measure the voltage and current of the injection order, and each voltage rise suppression unit 50, in the example shown in FIG. 13 As described above, the duplication prevention unit 124 serving as an anti-duplication unit for preventing the injection current _Im from being injected and the voltage and current measurement timings of the injection order m from overlapping each other among the voltage rise suppression devices 50 is provided. It may be provided.

The overlap prevention unit 124 controls the current injection unit 72 and the ratio calculation unit 62 to prevent the injection and measurement timings from overlapping each other between the voltage rise suppression devices 50.

The duplication prevention unit 124 may include, for example, a random number generation unit, and determine the injection and measurement timing by a random number.

Alternatively, the duplication prevention unit 124 monitors the collision of data on the CSMA / CD system (in short, the network is used for access control in the information communication field such as LAN, and detects a collision. The device that sent the data waits for a certain period of time and then retransmits the data) or the token ring method (in simple terms, it circulates special data called a token, and the device that acquired the token sends the data It may have the same function as the system capable of transmission.

When as described above, a plurality of distributed power owned equipment 20, each having the voltage rise suppression unit 50, be connected to the secondary side of the distribution lines of the same transformer, injection as well as infusion of injection current I _m Since the timing of measuring the voltage and current of the order m is different from each other in the voltage increase suppressing device 50 of each facility, the voltage α suppressing device 50 of the plurality of distributed power source possessing facilities 20 does not interfere with each other, and the ratio α ₁ is correctly set. Can be calculated. Therefore, appropriate phase advance reactive power Q can be output from each distributed power supply 30.

As in the example shown in FIG. 14, when the distributed power supply facility 20 has the interconnection transformer 126 and is connected to the high voltage distribution line 10, the voltage V _d at the connection point 18 can be measured. It can be difficult. In this case, the impedance of the power distribution system 2 side as viewed from the measurement point 36 is measured, when measuring the ratio alpha ₂ of the resistance / reactance, the impedance r _t + jx _t of interconnection transformer 126 is applied, the ratio alpha ₂ is The value is shown by the following formula.

[Equation 20]
α ₂ = (r + r _t ) / (x + x _t )

Therefore, from the ratio alpha _2, as the conversion factor to the primary side, i.e., the ratio of the power distribution system 2 viewed from the connecting point _{18 α 1 (= r / x} ) of interconnection transformer 126, transform coefficients shown by the following expression γ think of.

[Equation 21]
γ = α ₁ / α ₂
= {R / x} / {(r + r _t ) / (x + x _t )}
= (1 + x _t / x) / (1 + r _t / r)

Using the secondary voltage V _t2 at the measurement point 36, the overall impedance (r + r _t ) + j (x + x _t ) and its resistance component and reactance component as seen from the measurement point 36 when the distribution system 2 is viewed are measured by the method described above. can do. The resistance r _t and the reactance x _t of the interconnection transformer 126 are known. Using these, the conversion coefficient γ can be calculated according to the above equation (21).

As a result, using the ratio α ₂ and the conversion coefficient γ, the above-described second phase reactive power Q _b (see Equation 11) can be calculated by the following equation. Therefore, this calculation may be performed in the second reactive power calculation unit 64 (step 404 in FIG. 7).

[Equation 22]
Q _b = α ₁ · β · P = γ · α ₂ · β · P

(3) Simulation Result of Voltage Rise Suppression The result of simulation of voltage rise suppression control will be described using the model of FIG. 15 simulating the distributed power supply interconnection system shown in FIG.

The model shown in FIG. 15 includes a distributed power source holding facility 20 having a distributed power source 30 having a rated output of 5 kW on a secondary low voltage distribution line 16 of a 20 kVA single-phase three-wire transformer (columnar transformer) 14. This is an example in which the units are connected. The impedance Z _t of the transformer 14 was set to 0.016 + j0.021Ω. The impedance Z _d of the low-voltage distribution line 16 was 0.011 + j0.012Ω, and 0.017 + j0.013Ω when the line resistance was large.

Each distributed power supply facility 20 increased the output (active power P) at 1 kW / second from time 2 seconds, and fixed the output at 5 kW after time 7 seconds. This is a simulation of the case where the distributed power source 30 of each distributed power source possessing facility 20 is a solar power generation system, and the amount of solar radiation increases rapidly in 5 seconds due to clear clouds.

Table 1 shows the voltage at the transformer closest point 17 and each interconnection point 18 under the above conditions (this is 100V class between grounds), the active power P output from each facility 20, the phase reactive power Q and the operating power factor Pf. FIG. 16 to FIG. 27 show the results of measurement divided into the methods shown in FIG. The specific configuration of each part of the voltage rise suppressing device 50 shown in FIG. 6 is the same as that described with reference to FIGS. The fast reactive power Q is displayed as a negative value in this simulation. In addition, the driving power factor Pf rapidly increases in the initial stage, but this is a phenomenon only at the beginning of the control, and there is no particular problem.

In the case of using the conventional voltage rise suppressing device having the function shown in FIG. 2, the voltages V _d1 to V _{d3 at} each interconnection point 18 are suppressed to the voltage upper limit value of 107 V or less as shown in FIGS. . Focusing on the terminal equipment 20, the voltage V _d3 reaches the voltage upper limit value 107V at time t ₁ , and in response thereto, the phase advance reactive power Q ₃ increases, and at time t ₂ , the driving power factor Pf ₃ becomes the power factor lower limit. The value 0.85 is reached, and in response, the active power P ₃ starts to decrease. In this method, as shown in FIG. 17, the effective power P from the terminal equipment 20 is only about 2 kW, and the effective power depends on the position connected to the low voltage distribution line 16 as the voltage rise is suppressed. There is inequality in P etc.

In the case of using the voltage rise suppression device (β = 1) shown in FIG. 6, as shown in FIGS. 18 and 19, when the active power P starts to increase, the phase advance reactive power Q starts to increase accordingly. . This is because the above-described second phase reactive power Q _b contributes. The voltages V _d1 to V _{d3 at} each interconnection point 18 are suppressed with a margin below the voltage upper limit 107V. In this method, the inequality of the active power P is eliminated, but the driving power factor Pf ₃ is reduced to the power factor lower limit value 0.85 with the suppression of the voltage rise. Therefore, the system power factor of the three units is greatly reduced. This is because when the correction coefficient β = 1, the increase in the second phase reactive power Q _b accompanying the increase in the active power P is large.

In the case of using the voltage rise suppression device (β = 0.5) shown in FIG. 6, as shown in FIGS. 20 and 21, when the active power P starts to increase, the phase reactive power Q also increases accordingly. I'm starting. This is because the above-described second phase reactive power Q _b contributes. However, the increase in the phase reactive power Q is moderate. This is because β = 0.5. The voltages V _d1 to V _{d3 at} each interconnection point 18 are suppressed to a voltage upper limit value of 107 V or less. In this method, the inequality of the active power P accompanying the suppression of the voltage rise is eliminated, and the increase of the phase reactive power Q accompanying the increase of the active power P is moderate, and the driving power factor Pf is about 0 for all three units. .95 is getting better. Therefore, there is little decrease in the system power factor of the three units.

In the case of using the conventional voltage rise suppression device having the function shown in FIG. 2 (large line resistance), as shown in FIGS. 22 and 23, the voltages V _d1 to V _{d3 at} each interconnection point 18 are the voltage upper limit value 107V. It is suppressed to the following. If attention is paid to the terminal equipment 20, the voltage V _d3 reaches the voltage upper limit value 107V at time t ₃ , and in response thereto, the phase advance reactive power Q ₃ increases. At time t ₄ , the driving power factor Pf ₃ becomes the power factor lower limit. The value 0.85 is reached, and in response, the active power P ₃ starts to decrease. In this method, as shown in FIG. 23, the effective power P ₃ of the terminal equipment 20 is almost zero, and the effective power P or the like depends on the position connected to the low-voltage distribution line 16 as the voltage rise is suppressed. There is great inequality. This is because the voltage increase value ΔV becomes larger when the line resistance is large.

In the case of using the voltage rise suppression device shown in FIG. 6 (large line resistance, β = 1), as shown in FIGS. 24 and 25, when the active power P starts to increase, the phase reactive power Q is also increased accordingly. It is starting to increase. This is because the above-described second phase reactive power Q _b contributes. The voltages V _d1 to V _{d3 at} each interconnection point 18 are suppressed with a margin below the voltage upper limit 107V. In this method, the inequality of the active power P is eliminated, but the driving power factor Pf is reduced to the power factor lower limit value 0.85 as the voltage rise is suppressed. Therefore, the system power factor of the three units is greatly reduced. This is because when the correction coefficient β = 1, the increase in the second phase reactive power Q _b accompanying the increase in the active power P is large.

When the voltage rise suppression device shown in FIG. 6 is used (large line resistance, β = 0.5), as shown in FIGS. 26 and 27, when the active power P starts to increase, the phase advance reactive power Q is accordingly increased. Has also begun to increase. This is because the above-described second phase reactive power Q _b contributes. However, the increase in the phase reactive power Q is moderate. This is because β = 0.5. The voltages V _d1 to V _{d3 at} each interconnection point 18 are suppressed to a voltage upper limit value of 107 V or less. Focusing on the terminal equipment 20, the voltage V _d3 reaches the voltage upper limit value 107V at time t ₅ , and in response thereto, the phase advance reactive power Q ₃ increases (this is the first phase advance reactive power Q _a described above). The driving power factor Pf ₃ reaches the power factor lower limit value 0.85 at time t ₆ , and the increase of the active power P ₃ stops in response thereto. Also in this case, although the line resistance is large and the voltage increase value ΔV is likely to increase, the inequality of the active power P accompanying the voltage increase suppression is eliminated, and the driving power factor Pf is about 0.95 to 0.85. Range and pretty good. Therefore, there is little decrease in the system power factor of the three units. Thus, even when the line resistance is large and the voltage increase value ΔV tends to increase, it has been confirmed that the effect is obtained even if the correction coefficient β is set to 0.5.

(4) Other Examples of Distributed Power Supply 30 The distributed power supply 30 may be other than the solar power generation system of the above example. For example, as an example using an inverter, the distributed power source 30 may be a fuel cell power generation facility having a fuel cell and an inverter such as the inverter 34. Alternatively, as an example of having an AC generator and not using an inverter, the distributed power source 30 may be a cogeneration power generation facility, a wind power generation facility, or the like. The active power and / or reactive power output from the AC generator in response to a command signal from the voltage rise suppression device 50 (specifically, the active power command value P _com and the phase advance reactive power command value Q _com ). A known technique can be used as the technique for controlling the value to the command value. In brief, the active power can be controlled by controlling the phase of the output voltage of the AC generator. The reactive power can be controlled by controlling the field of the AC generator to control the magnitude of the output voltage.

2 Distribution System 16 Low Voltage Distribution Line 18 Interconnection Point 20 Distributed Power Supply Equipment 30 Distributed Power Supply 50 Voltage Increase Suppressor 54 Fundamental Voltage Determination Unit 56 Driving Power Factor Determination Unit 58 First Reactive Power Calculation Unit 60 Active Power Control Unit 62 Ratio calculation unit 64 Second reactive power calculation unit 66 Total reactive power calculation unit 68 Limit reactive power calculation unit 70 Reactive power control unit 72 Current injection unit 124 Duplication prevention unit P Active power Q Advanced phase reactive power α ₁ , α ₂ ratio

Claims

A voltage rise suppression device that controls the distributed power supply of the distributed power supply facility connected to the power distribution system and suppresses the voltage rise of the power distribution system,
Fundamental wave voltage determining means for determining whether a fundamental wave voltage at a connection point between the distribution system and the distributed power supply facility is higher than a predetermined voltage upper limit value;
Driving power factor determining means for determining whether or not the operating power factor of the distributed power source is equal to or higher than a predetermined power factor lower limit when the determination result in the fundamental wave voltage determining means is affirmative;
First reactive power calculation means for calculating and outputting a first phase reactive power according to a difference between the fundamental voltage and the voltage upper limit value when the determination result in the driving power factor determination means is affirmative When,
When the determination result by the driving power factor determination means is negative, the effective power that controls the distributed power source and outputs from the distributed power source is reduced according to the difference between the fundamental voltage and the voltage upper limit value. Power control means;
Current injection means for injecting an injection current of a non-integer multiple order of the fundamental wave of the power distribution system into the power distribution system;
Using the voltage and current of the injection order at the interconnection point, the fundamental wave component resistance (r 1 ), reactance (x 1 ) and ratio of the former to the latter (α 1 = r 1 / x 1 ) Ratio calculating means for calculating
A second reactive power calculation means for calculating and outputting a second phase reactive power by multiplying the active power output from the distributed power source, the ratio, and a correction coefficient β of 0 <β <1;
Total reactive power calculation means for adding the first and second phase reactive power to each other to calculate and output a total phase reactive power;
Using the active power output from the distributed power source and the power factor lower limit value, limit reactive power calculation means for calculating limit advanced reactive power that realizes the power factor lower limit value at the time of the active power, and
The total advanced phase reactive power is supplied to the distributed power source as an advanced phase reactive power command value with the upper limit suppressed to the value of the limit advanced phase reactive power, and the advanced phase reactive power output from the distributed power source is A voltage rise suppression device comprising: a reactive power control means for controlling to a phase advance reactive power command value.
The voltage rise suppressing device according to claim 1, wherein the correction coefficient β is set in a range of 0.5 to 0.8.
A plurality of distributed power supply holding facilities each having the voltage rise suppression device according to claim 1 or 2 is a distributed power supply interconnection system connected to a secondary distribution line of the same transformer,
Each of the voltage rise suppression devices is configured to inject injection currents of orders different from each other in the non-integer multiple order and to measure the voltage and current of the injection order. .
A plurality of distributed power supply holding facilities each having the voltage rise suppression device according to claim 1 or 2 is a distributed power supply interconnection system connected to a secondary distribution line of the same transformer,
Each of the voltage rise suppression devices is a non-integer multiple order injection of the same order injection current and measures the injection order voltage and current,
Furthermore, each of the voltage rise suppression devices includes an anti-duplication means for preventing the injection current injection and the measurement of the injection order voltage and current from overlapping each other between the voltage rise suppression devices. A distributed power interconnection system characterized by that.