JP3909337B2 - Single operation detector for distributed power supply - Google Patents

Description

  The present invention is applied to a distribution system having a configuration in which a distribution line is connected to a host system via a substation, and a distributed power source holding facility having a distributed power source is connected to the distribution line. More specifically, the present invention relates to a single operation detection device for detecting a single operation, and more specifically, the current injection device for injecting a plurality of orders of injection current for single operation detection is simplified. It is related with the means which enables miniaturization of.

  In recent years, power generation facilities such as wind power generation, waste power generation, small hydropower generation, and cogeneration (combined power generation) have been actively connected to the distribution lines. Such a power generation facility is called a distributed power source.

  If the circuit breaker of the power company's substation is opened due to a grid fault, etc., and the power supply from the upper system stops, if the distributed power supply continues to operate (ie, single operation), the power supply from the upper system Since the voltage continues to be applied to the distribution line even though the operation stops, an electric shock accident or the like may occur. Therefore, as a first step, it is necessary to reliably detect such a stop of power supply from the host system, that is, a single operation of the distributed power source. Furthermore, as the second step, it is necessary to disconnect (disconnect) the distributed power source from the distribution system.

  As an example of a device that detects the independent operation of a distributed power supply, it is applied to a power distribution system with a configuration in which a distribution line is connected to a host system via a substation, and a distributed power supply facility with a distributed power supply is connected to this distribution line. A non-integer multiple order (for example, 2.4th order, 2.5th order) larger than 1 times the fundamental wave of the power distribution system from the distribution line to the distributed power supply facility. 1) of the plurality of injection orders of the current injection device for injecting injection currents of a plurality of orders different from each other and the distribution system as viewed from the power receiving point of the distributed power supply facility A supply stop detection device that measures the impedance or admittance of the above injection order and detects that the power supply from the host system has stopped from a change in the impedance or admittance. Independent operation detecting apparatus has already been proposed that (for example, see Patent Document 1).

  The use of multiple orders of injection current means that even if the distribution system impedance or admittance cannot be measured correctly at one injection order, the distribution system impedance or admittance must be measured correctly at other injection orders. This is because it is possible to more reliably detect the stop of power supply from the host system.

  Although the configuration of the current injection apparatus for injecting the injection currents of a plurality of orders as described above is not described in Patent Document 1, there are conventionally two types.

(1) As shown in FIG. 12, the first current injection device 100 has a plurality of orders of m1 that are non-integer multiples (ie, sub-orders) m of the fundamental wave voltage of the power distribution system and have different orders. , when m @ 2, m3, this three injection orders m1, m @ 2, m3 injected sinusoidal signal of S _m1, S _{m @ 2,} the three respectively generating the S _m3 injection signal generator 102 to 104, from their An adder 106 that synthesizes (adds) the injection signals S _m1 , S _m2 , and S _m3 , a sine wave amplifier 108 that amplifies the combined signal S _m1 + S _m2 + S _m3 and outputs it as an injection current K _m , and the lead-in line And a series capacitor 110 that prevents (cuts) the fundamental voltage of the distribution system from being applied to the sine wave amplifier 108 from the side.

  (2) As described in Non-Patent Document 1 (see FIG. 4 on page 946 (60) and the description thereof), the second current injection device applies the square wave voltage of the non-integer multiple order (for example, m1). A series LC resonance circuit that is in a series resonance state in the vicinity of the frequency of the non-integer multiple order (for example, m1) is connected in series to the generated square wave voltage generator, and the sine of the non-integer multiple order (for example, m1). A current injection circuit that outputs a wavy injection current is connected in parallel by the number of injection orders (for example, three circuits of injection orders m1, m2, and m3).

JP 2001-251767 (paragraphs 0009-0010, FIG. 1) Fumio Yamamoto and three others, “Development of an independent operation detection device for distributed power sources-Interharmonic injection method”, Journal of the Institute of Electrical Installation, Japan Institute of Electrical Installation, December 10, 2004, Volume 24, No. 12, pp. 943 (57) -952 (66)

  Each of the first and second current injection devices has a complicated configuration, and there is a problem in that the current injection device, and hence the isolated operation detection device, is hindered from being downsized.

  That is, in the first current injection device 100, the injection signal generators 102 to 104, etc., corresponding to the number of injection orders are necessary, and in addition, the adder 106, the sine wave amplifier 108, and the series capacitor 110 are necessary. The structure is complicated and the size reduction is hindered.

  Moreover, a PWM (Pulse Width Modulation) circuit is often used as the sine wave amplifier 108, but the PWM circuit has a large power loss (switching loss) at the time of switching. The larger the size, the more heat is generated. From this point of view, the current injection device has been hindered from being downsized.

  The second current injection device also requires current injection circuits as many as the number of injection orders, so that the configuration is complicated, which hinders downsizing.

  In addition, a reactor is required to form a series LC resonance circuit, and power loss due to the resistance inevitably present in the reactor is large. Similarly to the above, a current injection device from the viewpoint of heat generation due to power loss Was hindering downsizing.

  In view of this, the first aspect of the present invention is to make it possible to reduce the size of the current injection device and hence the isolated operation detection device by simplifying the configuration of the current injection device for injecting the injection current of a plurality of orders and reducing the loss. It is aimed.

  Conventionally, as described in both documents, the injection order is less affected by the resonance phenomenon between the inductive reactance component existing in the power distribution system and the capacitive reactance of the power factor improving capacitor. Less than the fourth order.

  However, an injection current is supplied from a distributed power supply facility connected to a distribution system having a small short-circuit capacity (in other words, a small impedance of the system) such as an extra-high voltage (that is, a voltage exceeding 7 kV) distribution system. In the case of injection, since the impedance of the distribution system viewed from the power receiving point is small, if the injection current is small, the voltage of the injection order is small and it is difficult to detect it accurately. Therefore, the impedance of the injection order or its inverse It is difficult to accurately detect the admittance.

  As a countermeasure, it is conceivable to increase the injection order, for example, to the fourth order or higher. In such a case, the impedance of the distribution system viewed from the power receiving point is generally composed of an inductive reactance component, which is jmx (j is an imaginary unit, m is an injection order, and x is a primary inductive reactance. Component) and measured. Therefore, if the injection order m is increased (that is, m is increased), a high voltage is generated in proportion to the injection order even if the injection current amount is the same, and this is measured. Admittance measurement is easier and more accurate.

  However, as described above, when the fourth order or higher is used as the injection order, the injection order is susceptible to the resonance phenomenon between the inductive reactance component existing in the power distribution system and the capacitive reactance of the power factor correction capacitor. There is a problem that it is difficult to detect an isolated operation (see, for example, page 947 (61) of Non-Patent Document 1).

  More specifically, a high voltage distribution bank having a high voltage bank transformer, a high voltage consumer equipment, and no reactor (no L) power factor correction capacitor is connected to the special high voltage distribution line. 1 (see high voltage bank transformer 42, high voltage consumer equipment 44, power factor improving capacitor 46, high voltage distribution bank 16 in FIG. 1), the induction reactance and L-less power factor of the high voltage bank transformer in the injection order. There is a possibility that series resonance occurs due to the capacitance reactance of the capacitor for improvement, and in this case, even in the single operation state, the impedance of the injection order of the distribution system viewed from the power receiving point does not increase (in other words, In this case, the admittance is not reduced), and the voltage is not increased. Therefore, the isolated operation cannot be detected.

  As described above, when the injection order is set to the fourth order or higher, the voltage of the injection order component can be increased, but there arises a problem that it becomes difficult to detect an isolated operation due to the influence of the series resonance phenomenon in the distribution system. In particular, since the high voltage distribution bank as described above is generally connected to the special high voltage distribution line, the influence of the series resonance phenomenon is caused when the fourth or higher injection current is injected into the special high voltage distribution line. It is easy to receive.

  Accordingly, a second object of the present invention is to use an injection order of the fourth order or higher and eliminate the influence of the series resonance phenomenon in the power distribution system so that the isolated operation of the distributed power supply can be accurately detected. It is said.

  In order to achieve the first object, one of the isolated operation detection devices according to the present invention is as follows. (A) One time of the fundamental wave of the distribution system from the distribution line to the service line having the distributed power supply A current injection device that injects injection currents of a plurality of orders that are non-integer multiple orders that are larger than each other, and (b) the plurality of distribution systems as viewed from the power reception point of the distributed power supply facility A supply stop detection device that measures the impedance or admittance of one or more injection orders out of the injection orders and detects that the power supply from the host system has been stopped based on a change in the impedance or admittance. And (c) the current injection device is connected in series to a square wave voltage generator that generates a square wave voltage of the non-integer multiple order, and an output line of the square wave voltage generator. And a capacitor for differentiating the square wave voltage from the square wave voltage generator and outputting a pulse-like injection current, wherein the injection current has a plurality of orders different from each other in the non-integer multiple order. It is characterized by injecting a pulsed injection current containing as a component.

  According to this isolated operation detection device, the current injection device injects a pulse-shaped injection current containing a plurality of orders of injection currents of the non-integer multiple order and different orders from each other. A single current injection device including a voltage generator and a capacitor can substantially inject multiple orders of injection current.

  In order to achieve the above first and second objects, the other of the isolated operation detection device according to the present invention is as follows: (a) a distribution line from the distribution line to the distributed power supply facility has a basic power distribution system; A current injection device that injects injection currents of a plurality of orders that are non-integer multiple orders greater than one wave and have different orders, and (b) the distribution system as viewed from a power receiving point of the distributed power supply facility A supply stop detection device that measures impedance or admittance of one or more injection orders out of the plurality of injection orders and detects that power supply from the host system has been stopped based on a change in the impedance or admittance And (c) the current injection device includes a square wave voltage generator for generating a square wave voltage of the non-integer multiple order and an output line of the square wave voltage generator. And a capacitor for differentiating the square wave voltage from the square wave voltage generator and outputting a pulsed injection current, and having the non-integer multiple order and the fourth order or higher. Injecting a pulsed injection current containing a plurality of different orders of injection current as a harmonic component, and (d) the supply stop detection device includes each of the plurality of injection orders in the lead-in line Selecting one or more injection orders in descending order of the voltage value of the injection order, and detecting that the power supply from the host system has been stopped from the change in impedance or admittance at the selected injection order; It is characterized by that.

  According to this isolated operation detection device, the current injection device is configured to generate a pulse-like injection current that includes the non-integer multiple order injection currents of a plurality of orders different from each other in the fourth order or higher as harmonic components. Since the injection is performed, it is possible to substantially inject an injection current of a plurality of orders by a single current injection device including a square wave voltage generator and a capacitor.

  In addition, since a plurality of orders of injection currents that are substantially different from each other in the fourth order or higher are injected from the current injection device, some of the injection orders happen to coincide with the series resonance order in the distribution system. Even if the voltage of the corresponding injection order does not increase during the single operation of the distributed power source, the voltages of the other injection orders increase as planned.

  And since the supply stop detection device selects one or more injection orders from the plurality of injection orders in the descending order of the voltage value of each injection order in the lead-in line and uses it for isolated operation detection, it coincides with the series resonance order. Independent operation detection can be performed by automatically selecting an injection order that avoids the injection order.

  The supply stop detection device (a) measures the impedance or admittance of the plurality of injection orders, respectively, and determines that the power supply from the host system has stopped due to a change in the impedance or admittance of each injection order. A plurality of determination means for determining for each injection order; and (b) an order selection means for selecting one or more injection orders in descending order of the voltage value of each injection order in the lead-in line from the plurality of injection orders; (C) You may provide the validation means which validates only the output from the said determination means about the injection | pouring order selected by the said order selection means.

  In order to achieve the first and second objects described above, still another independent operation detection device according to the present invention includes: (a) a lead-in line from the distribution line to the distributed power source holding facility, A current injection device that injects injection currents of a plurality of orders that are non-integer multiple orders that are larger than one time of the fundamental wave and that have different orders from each other; A supply stop detection device for measuring the admittance of one or more injection orders among the plurality of injection orders of the system and detecting that the power supply from the higher system is stopped from the change of the admittance And (c) the current injection device is connected in series to the square wave voltage generator for generating the square wave voltage of the non-integer multiple order and the output line of the square wave voltage generator, and the square wave voltage generator Voltage generation And a capacitor for differentiating the square wave voltage from the capacitor and outputting a pulse-like injection current, and the harmonics of the non-integer multiple order injection currents of a plurality of orders different from each other in the fourth order or higher. (D) the supply stop detection device has one or more of the plurality of injection orders in order from the smallest absolute value of the admittance of each injection order; An injection order is selected, and it is detected from the change in the admittance at the selected injection order that the power supply from the upper system is stopped.

  According to this isolated operation detection device, the current injection device is configured to generate a pulse-like injection current that includes the non-integer multiple order injection currents of a plurality of orders different from each other in the fourth order or higher as harmonic components. Since the injection is performed, it is possible to substantially inject an injection current of a plurality of orders by a single current injection device including a square wave voltage generator and a capacitor.

  In addition, since a plurality of orders of injection currents that are substantially different from each other in the fourth order or higher are injected from the current injection device, some of the injection orders happen to coincide with the series resonance order in the distribution system. Even if the admittance of the corresponding injection order does not decrease during the independent operation of the distributed power source, the admittance of the other injection orders decreases as planned.

  Since the supply stop detection device selects one or more injection orders from the plurality of injection orders in order of decreasing absolute value of the admittance of each injection order and uses it for the isolated operation detection, the injection that matches the series resonance order is used. Independent operation detection can be performed by automatically selecting an injection order avoiding the order.

  The supply stop detection device (a) measures each of the admittances of the plurality of injection orders, and indicates that the power supply from the upper system has been stopped for each injection order from a change in the admittance of each injection order. A plurality of determination means for determining; and (b) order selection means for selecting one or more injection orders from the plurality of injection orders in ascending order of absolute value of the admittance of each injection order, and (c) the order An enabling means for validating only the output from the determining means for the injection order selected by the selecting means may be provided.

  In order to achieve the first and second objects described above, still another independent operation detection device according to the present invention includes: (a) a lead-in line from the distribution line to the distributed power source holding facility, A current injection device that injects injection currents of a plurality of orders that are non-integer multiple orders that are larger than one time of the fundamental wave and that have different orders from each other; A supply stop detection device for measuring the impedance of one or more injection orders of the plurality of injection orders of the system and detecting that the power supply from the higher-order system is stopped from the change in the impedance; And (c) the current injection device is connected in series to the square wave voltage generator for generating the square wave voltage of the non-integer multiple order and the output line of the square wave voltage generator, and the square wave voltage generator Voltage A capacitor for differentiating a square wave voltage from the living device and outputting a pulse-like injection current, wherein the non-integer multiple order injection currents of a plurality of orders different from each other in the fourth or higher order are provided. Injecting a pulsed injection current contained as a harmonic component, (d) the supply stop detection device is configured to select 1 from the plurality of injection orders in descending order of the absolute value of the impedance of each injection order. The above injection order is selected, and it is detected from the change in the impedance at the selected injection order that the power supply from the host system is stopped.

  According to this isolated operation detection device, the current injection device is configured to generate a pulse-like injection current that includes the non-integer multiple order injection currents of a plurality of orders different from each other in the fourth order or higher as harmonic components. Since the injection is performed, it is possible to substantially inject an injection current of a plurality of orders by a single current injection device including a square wave voltage generator and a capacitor.

  In addition, since a plurality of orders of injection currents that are substantially different from each other in the fourth order or higher are injected from the current injection device, some of the injection orders happen to coincide with the series resonance order in the distribution system. Even if the impedance of the corresponding injection order does not increase during the independent operation of the distributed power source, the impedance of the other injection orders increases as planned.

  The supply stop detection device selects one or more injection orders from the plurality of injection orders in descending order of the absolute value of the impedance of each injection order and uses it for isolated operation detection. Therefore, the injection stop coincides with the series resonance order. Independent operation detection can be performed by automatically selecting an injection order avoiding the order.

  The supply stop detection device (a) measures the impedance of each of the plurality of injection orders, and determines that the power supply from the upper system has been stopped for each injection order from the change in impedance of each injection order. A plurality of determination means for determining; (b) an order selection means for selecting one or more injection orders in descending order of the absolute value of the impedance of each injection order from among the plurality of injection orders; and (c) the order An enabling means for validating only the output from the determining means for the injection order selected by the selecting means may be provided.

  According to the first aspect of the present invention, since a plurality of orders of injection current can be injected substantially by a single current injection device including a square wave voltage generator and a capacitor, injection of a plurality of orders is possible. The configuration of the current injection device for injecting current is simplified, and the current injection device can be downsized.

  Moreover, since the power loss in the capacitor of the current injection device is generally very small, there is almost no heat generation, and even if the injection current is increased, the heat generation is very small. Miniaturization is possible.

  Combined with the above-described effects, according to the present invention, the current injection device and, hence, the isolated operation detection device can be miniaturized.

  According to the invention described in claims 2 to 7, since the current injection device as described above is provided, the same effect as that of the invention described in claim 1 can be obtained.

  In addition, since the current injection device and the supply stop detection device as described above are provided, it is possible to automatically select the injection order that avoids the injection order that coincides with the series resonance in the distribution system and to detect the independent operation of the distributed power source. Can do. As a result, it is possible to detect the isolated operation of the distributed power supply with high accuracy by using an injection order of the fourth order or higher and eliminating the influence of the series resonance phenomenon in the power distribution system.

  Furthermore, by using an injection order of 4th order or higher, it is possible to measure the voltage, impedance or admittance of the injection order component without increasing the injection current as compared with the case of using an injection order of less than 4th order. Since it becomes easy and becomes highly accurate, it becomes possible to detect an isolated operation with high accuracy. Therefore, if it is not necessary to increase the injection current, the capacity of the current injection device can be reduced, and the current injection device can be downsized, and thus the isolated operation detection device can be downsized.

  FIG. 1 is a single-line connection diagram showing an example of a power distribution system including a distributed power supply isolated operation detection device according to the present invention.

  This distribution system has a configuration in which a distribution line 10 is connected to a host system 2 via a substation 4. The substation 4 includes a transformer 6 and a circuit breaker 8 that connects the secondary side of the transformer 6 and the distribution line 10. In addition, although the distribution line in the case of the extra high voltage in which a voltage exceeds 7 kV is called an extra high piezoelectric line, in this specification, it will be referred to as a distribution line in this case as well.

  In this example, the distribution line 10 is a distribution line having an extra high voltage (that is, a voltage exceeding 7 kV), and the voltage is, for example, 11 kV, 22 kV, 33 kV, 66 kV, or 77 kV. However, the distribution line 10 may be a high-voltage distribution line (that is, a voltage of 7 kV or less), and the voltages in this case are, for example, 3.3 kV and 6.6 kV.

  In this example, the distribution line 10 is connected with an extra-high customer facility 12, a distributed power source holding facility 14 having a distributed power source, and a high voltage distribution bank 16.

  As described above, the high-voltage distribution bank 16 includes the high-voltage bank transformer 42, the high-voltage customer facility 44, and the L-less power factor improving capacitor 46.

  In this example, an isolated operation detection device 30 as described below is provided in the distributed power supply facility 14 connected to the distribution line 10 at the power receiving point P.

  In the distributed power supply facility 14, a local bus 22 is connected to the power receiving point P via a lead-in line 18 and a circuit breaker 20. A distributed power supply 28 is connected to the local bus 22 via a local load 24 and a transformer 26, and power synchronized with the fundamental wave of the distribution system is supplied from the distributed power supply 28 to the local bus 22. . This is called “interconnection operation”.

  In the event of a system fault or the like, the circuit breaker 8 of the substation 4 is opened. At that time, as described above, when the distributed power source 28 is operating (ie, isolated operation), an electric shock accident or the like may occur. It is necessary to disconnect (disconnect) the distributed power source 28 from the distribution system by opening 20.

  Therefore, in this embodiment, an isolated operation detection device 30 for detecting the isolated operation of the distributed power supply 28 is provided in the distributed power supply facility 14. The isolated operation detection device 30 includes a current injection device 32 and a supply stop detection device 34.

An instrument transformer 38 and an instrument current transformer 40 for measuring the voltage and current in the service line 18 are connected to the service line 18, and the measurement voltage V _t and the measurement voltage obtained by measuring these 38 and 40 are connected to the service line 18. I _t is supplied to the supply stop detecting device 34.

In this example, the current injection device 32 is connected to the lead-in wire 18 and, moreover, to the power receiving point P and the distribution line 10 via the voltage matching transformer 36, to a non-integer multiple order of the fundamental wave voltage of the distribution system (i.e., a band number Moreover degree each other a degree) m is one that injects a pulsed injection current J _m of containing a plurality of different injection current orders as component (fundamental wave component and harmonic components).

First, the current injection device 32 will be described in detail. A more specific example of the current injection device 32 is shown in FIG. The current injection device 32 includes a square wave voltage generator 50 that generates a square wave voltage RV _m of the non-integer multiple order m (for example, 2.3 order, 2.5 order), and the square wave voltage generator 50. and a capacitor 52 for outputting the injection current J _m of differentiating a square wave voltage RV _m pulsed from the square-wave voltage generator 50 in the output line are connected in series.

With such a single current injection device 32, it is possible to substantially inject multiple orders of injection current. More specifically, it is possible to inject an injection current J _m containing the following number of injection current odd (1,3,5,7, ...) times the non-integer multiple order m as a component. In other words, it is possible to inject an injection current J _m obtained by combining the injection current of the plurality orders. For example, when the non-integer multiple order m is 2.5th order, the injection currents of 2.5th order, 7.5th order, 12.5th order, 17.5th order, etc. are components based on the fundamental wave of the distribution system injection current J _m containing as can be injected. This principle will be described with reference to FIGS.

FIG. 6 is a model circuit diagram composed of the square wave voltage generator 50 and the series capacitor 52. In this circuit, the square wave voltage RV _m from the square wave voltage generator 50 can be differentiated by the capacitor 52 to flow (output) the pulsed injection current J _m . The square wave voltage RV _m is expressed by the following equation according to the Fourier series expansion equation of a square wave. Here, the square wave voltage RV _m is assumed to be 1. t is time, m is the order of the square wave voltage RV _m , f _m is its frequency, and ω _m is its angular frequency (ω _m = 2πf _m ). n is an order that makes the non-integer multiple order m the first order (that is, the fundamental wave; the same applies hereinafter), and is an odd natural number (1, 3, 5, 7,...). Accordingly, the following voltages and currents are of the order of n · m with respect to the fundamental wave of the distribution system.

[Equation 1]
_{RV m = {4 / π}} · {sinω m t + (1/3) sin3ω m t
+ (1/5) sin5ω _m t +... + (1 / n) sinnω _m t}

The above formula indicates that the square wave voltage RV _m contains the following voltages as components and is a combination of these voltages.

(1) Voltage V _{1 at} fundamental frequency f _m ... Magnitude 4 / π
(2) third harmonic voltage V ₃ · · · the magnitude of the frequency 3f _m 4/3 [pi]
(3) fifth harmonic frequency 5f voltage of _m V ₅ · · · size 4/5 [pi]
...
(4) the voltage of the n-th harmonic frequency nf _m V _n · · · size 4 / n?

Next, the impedance Z _n of each order n of the capacitor 52 is expressed by the following equation. Here, C is the capacitance of the capacitor 52, and j is an imaginary unit.

[Equation 2]
Z _n = 1 / jnω _m C

Accordingly, the current I _n of the order _n is expressed by the following equation.

[Equation 3]
I _n = V _n / Z _n
= J4 / πω _m C

The above equation shows that the pulsed injection current J _m flowing through the capacitor 52 contains the following currents of the same magnitude as components. In other words, the current flows as a combination of the following currents.

(1) Current I _{1 with} fundamental frequency f _m ... Magnitude 4 / πω _m C
(2) 3 primary current I ₃ of the harmonic frequency 3f _m ... Id (3) fifth harmonic frequency 5f _m of the current I ₅ ... Ditto ...
(4) current of the n-th harmonic frequency nf _m I _n · · · Same as above

Therefore, current injection apparatus having the circuit configuration of FIG. 6 can be injected pulsed injection current J _m containing the order together with a size of the same is different injection current orders as components.

However, since there is always a resistance component in an actual electric circuit, a model circuit closer to reality in which a resistor 54 having a small value is inserted in series in the output line is shown in FIG. The current injection device 32 shown in FIG. 2 is equivalent to this circuit equivalently. Also, the waveforms of the square wave voltage RV _m and the injection current J _m simulated by this circuit and their frequency characteristics are shown in FIGS. Here, the frequency f _m of the square wave voltage RV _m is 150 Hz (that is, 2.5th order when the fundamental wave of the distribution system is 60 Hz), the magnitude is 100 V, and the capacitance C of the capacitor 52 is 100 μF (impedance is 150 Hz). The resistance value R of the resistor 54 was 1Ω.

As shown in FIG. 9, the frequency characteristic of the square wave voltage RV _m shown in FIG. 8 is that, as theoretically, the magnitude of the harmonic component of the order n is reduced at a ratio of 1 / n with respect to the fundamental wave component. Yes.

Further, as shown in FIG. 11, the frequency characteristic of the injection current J _m shown in FIG. 10 includes the series resistance 54, so that the magnitude of the harmonic component gradually decreases as the order n increases. .

  As described in detail above, a plurality of orders of substantially multiple orders are achieved by a single current injection device 32 shown in FIG. 2, that is, by a single current injection device 32 comprising a square wave voltage generator 50 and a capacitor 52. Since the injection current can be injected, the configuration of the current injection device 32 for injecting a plurality of orders of injection current is simplified, and the current injection device 32 can be downsized.

Moreover, since the power loss in the capacitor 52 of the current injection device 32 is generally very small, there is almost no heat generation, and even if the injection current _Jm is increased, the heat generation is very small. The current injection device 32 can be downsized.

  Combined with the above-described effects, the current injection device 32 and thus the isolated operation detection device 30 can be downsized.

  Since the impedance of the circuit elements on the distribution system side including the transformer 36 and the like is much lower than that of the capacitor 52 of the current injection device 32, the impedance of the circuit elements on the distribution system side has little influence on the above characteristics. Can not be said.

  Further, considering the concern that the order of n times the non-integer multiple order m may be an integral multiple of the fundamental wave of the distribution system, for example, if the non-integer multiple order m is 2.5 order as in the above example, The order of the odd harmonic component based on the fundamental wave of the distribution system is as follows.

(1) 3rd harmonic (3m) ... 7.5th order (2) 5th harmonic (5m) ... 12.5th order (3) 7th harmonic (7m) ... 17.5th order

  Thus, since the order m is a non-integer multiple order, it can be avoided that an arbitrary odd order n is an integral multiple of the distribution system fundamental wave order. That is, for any odd order n, a non-integer multiple order can always be used.

Further, as can be seen from the above description, according to the current injection device 32, a plurality of the non-integer multiple orders and the orders different from each other in the fourth or higher order can be obtained by one current injection device 32. It is possible to inject a pulse-like injection current J _m containing an injection current of the following order as a harmonic component.

  In order to prevent a harmonic component higher than necessary from being injected into the lead-in wire 18 from the current injection device 32, an unnecessarily high harmonic component (for example, a distribution system) Means (for example, a series reactor having a minute inductance) that blocks higher harmonic components higher than the 17.5th order with respect to the fundamental wave may be provided.

  Next, the supply stop detection device 34 will be described in detail. When substantially multiple orders of injection current are injected from the current injection device 32 as described above, as the supply stop detection device 34, the distribution system viewed from the power reception point P of the distributed power supply facility 14 A known supply stop detection device that measures the impedance or admittance of one or more injection orders out of a plurality of injection orders and detects that the power supply from the higher-order system 2 has stopped from the change in the impedance or admittance ( For example, you may use the supply stop detection apparatus of the said patent document 1.

  However, when the fourth order or higher is used as the injection order and the measurement (detection) order, it is preferable to employ a supply stop detection device 34 as described below.

  In the following embodiment, the case where the plurality of orders of the fourth or higher order is three will be described as an example, but the present invention is not limited to three. Three non-integer multiple orders (that is, injection orders) are m1, m2, and m3. These are, for example, the above-mentioned 7.5th order, 12.5th order, and 17.5th order (both are based on the fundamental wave of the distribution system), but are not limited thereto.

The supply stop detection device 34 selects one or more injection orders from the plurality of injection orders, specifically, from the three injection orders m1, m2, and m3 in this embodiment by the means described below. and, at the injection order that the selected impedance or admittance of the distribution system as viewed from the receiving point P is calculated based on the measured voltage V _t and the measured current I _t, the change of the impedance or admittance, the upper grid 2 It is determined that the power supply from is stopped, and a supply stop detection signal S indicating that the power supply from the upper system 2 is stopped, that is, indicating the independent operation of the distributed power supply 28 is output. In this example, the circuit breaker 20 is opened in response to the supply stop detection signal S.

  The means for selecting the one or more injection orders are roughly divided into the following three.

  (1) Means for selecting one or more injection orders in descending order of the voltage values of the respective injection orders m1, m2, and m3 in the lead-in line 18.

  (2) Means for selecting one or more injection orders in ascending order of absolute values of the admittances of the respective injection orders m1, m2, and m3.

  (3) Means for selecting one or more injection orders in descending order of the absolute value of the impedance of each of the injection orders m1, m2, and m3.

  A more specific example of the supply stop detection device 34 is shown in FIG. This supply stop detection device 34 is an example in which the selection means (1) is adopted.

The outage detecting device 34, the measurement voltage V _t, receives a measured current I _t, a low-pass filter 62 and 64 for removing unnecessary components in the sampling of the discrete Fourier transformer 71 to 76 to be described later, then the output AD converters 66 and 68 for converting the analog voltage and current to digital and outputting the voltage V _d and current I _d , respectively. The voltage V _d and current I _d output from the AD converters 66 and 68 are respectively supplied to three discrete Fourier transformers 71 to 73 for voltage and three discrete Fourier transformers 74 to 76 for current. .

Discrete Fourier transformer 71 to 73, the voltage V _d which digitized measurement voltage V _t each Fourier transform, the three orders m1, m @ 2, m3 of the voltage V _m1, V _m2, V _m3 respectively extracted And output.

Discrete Fourier transformer 74 to 76, and each Fourier transform the current I _d which digitized measurement current I _t, the three injection orders m1, m @ 2, m3 of the current I _m1, I _m2, I _m3 respectively Extract and output.

The voltages V _{m1 to} V _m3 , currents I _{m1 to} I _m3 , admittances Y _m1 to Y _m3 , and impedances Z _{m1 to} Z _m3 described later are all expressed in complex numbers.

The voltage V _m1 from the discrete Fourier transformer 71 and the current I _m1 from the discrete Fourier transformer 74 are supplied to the computing unit 81, the voltage V _m2 from the discrete Fourier transformer 72 and the voltage I _m2 from the discrete Fourier transformer 75. Is supplied to the calculator 82, and the voltage V _m3 from the discrete Fourier transformer 73 and the current I _m3 from the discrete Fourier transformer 76 are supplied to the calculator 83. Each of the calculators 81 to 83 calculates the admittances Y _m1 , Y _m2 , and Y _m3 of the injection orders m1, m2, and m3 using the supplied voltages and currents according to the following equations, respectively, The absolute values | Y _m1 |, | Y _m2 |, | Y _m3 | are calculated and output to the comparators 86 to 88, respectively.

[Equation 4]
Y _m1 = I _m1 / V _m1
Y _m2 = I _m2 / V _m2
Y _m3 = I _m3 / V _m3

Each of the comparators 86 to 88 compares the absolute values | Y _m1 |, | Y _m2 |, | Y _m3 | of the respective admittances with predetermined reference values R ₁ , R ₂ , R ₃ , respectively. Output S ₁ , S ₂ and S ₃ are turned on, respectively, when the absolute value is smaller than the latter (reference value). This is because when the substation circuit breaker 8 is opened and the power supply from the upper system 2 is stopped to enter the single operation state, the parallel impedance of the substation transformer 6 connected to the distribution line 10 is lost, and the distribution This is because the system impedance becomes very large, in other words, the admittance of the distribution system becomes very small. As a result, the power supply from the upper system 2 can be determined for each of the injection orders m1, m2, and m3. The magnitudes of the reference values R ₁ , R ₂ , R ₃ are, for example, about 1/2 of the absolute values | Y _m1 |, | Y _m2 |, | Y _m3 | of each admittance during the interconnection operation. It ’s fine.

Note that turning on the outputs S _{1 to} S ₃ , the outputs S _{4 to} S ₉ and the outputs E _{1 to} E ₃ described below are “1” in terms of logical values, When it is off other than “0”, it is “0”.

Outputs S _{1 to} S ₃ from the comparators 86 to 88 are supplied to counters 91 to 93, respectively. Each counter 91 through 93, each output S ₁ to S ₃ of the duration of ON between predetermined settling time (e.g. 0.3 seconds to 1.0 seconds) in a matched set state each output S ₄ to S ₆ Are turned on and reset when the outputs S _{1 to} S ₃ are turned off, and the outputs S _{4 to} S ₆ are turned off. Providing such counters 91 to 93 can prevent erroneous detection due to instantaneous fluctuation of the admittance due to some cause other than the single operation.

The low-pass filters 62 and 64, the AD converters 66 and 68, the discrete Fourier transformers 71 to 76, the arithmetic units 81 to 83, the comparators 86 to 88, and the counters 91 to 93 include the plurality of injection orders m1 to m3. The admittances Y _{m1 to} Y _m3 are respectively measured, and the change in the admittances Y _{m1 to} Y _m3 of the injection orders _m1 to _m3 is determined for each injection order _m1 to _m3. A plurality of (three in this example) determination means are configured.

  The supply stop detection device 34 further includes an order selection means for selecting one or more injection orders in descending order of voltage values of the injection orders m1 to m3 in the lead-in line 18 from the plurality of injection orders m1 to m3. An order selector 96 is provided.

More specifically, the order selector 96 is supplied (inputted) with the voltages V _{m1 to} V _m3 corresponding to the voltages of the injection orders _{m1 to m3 in the} lead-in line 18 from the discrete Fourier transformers 71 to 73. . The input voltages V _m1 , V _m2 and V _m3 correspond to the outputs E ₁ , E ₂ and E ₃ , respectively. The order selector 96 has means for calculating the absolute values | V _m1 |, | V _m2 |, | V _m3 | of the voltages V _{m1 to} V _m3 , respectively. The absolute values | V _m1 |, | One output E ₁ , E _2, or E ₃ corresponding to the one having the maximum value among V _m2 | and | V _m3 | is turned on. For example, if | V _m1 | is the maximum value, the output E ₁ corresponding to the input voltage V _m1 is turned on. As a result, one injection order m1 is selected.

Alternatively, the order selector 96 turns on _two or more corresponding outputs E ₁ , E _2, or E ₃ in descending order from the absolute values | V _m1 |, | V _m2 |, | V _m3 |. Things can be used. For example, when | V _m1 | is the largest and | V _m2 | is the second largest, the outputs E ₁ and E ₂ corresponding to the input voltages V _m1 and V _m2 are turned on. As a result, two injection orders m1 and m2 are selected.

Outputs S _{4 to} S ₆ from the counters 91 to 93 and outputs E _{1 to} E ₃ from the order selector 96 are input to AND circuits 101 to 103, respectively. The AND circuit 101 calculates the logical product of the outputs S ₄ and E ₁ and turns on the output S ₇ when both the outputs S ₄ and E ₄ are on. Similarly, the AND circuit 102 turns the output S ₈ when the output S ₅ and E ₂ are both turned on. AND circuit 103, the output S ₆ and E ₃ to turn on the output S ₉ when both ON. The OR circuit 106 to which the outputs S _{7 to} S ₉ are supplied takes a logical sum of these outputs and outputs the supply stop detection signal S when at least one of the outputs S _{7 to} S ₉ is on. Output.

The AND circuits 101 to 103 and the OR circuit 106 only output the output from the determination means (of outputs S _{4 to} S ₆ ) for the injection order (one or more of m 1 to m 3) selected by the order selector 96. 1 or more) is enabled.

As described above, according to this isolated operation detecting apparatus 30, from the current injection unit 32, substantially so to one another order than fourth order to inject an injection current J _m of different orders m1 to m3, the Among the injection orders m1 to m3, there are those that happen to coincide with the series resonance order in the distribution system. For example, as described above, the induction reactance of the high voltage bank transformer 42 constituting the high voltage distribution bank 16 and the L-less power factor improvement Even if the order of the series resonance is caused by the capacitance reactance of the capacitor 46 and the voltage of the matched injection order does not increase during the independent operation of the distributed power supply 28, the voltage of the other injection orders is scheduled. It grows as expected.

  Since the supply stop detection device 34 selects one or more injection orders in descending order of the voltage value of each injection order in the lead-in line 18 from among the plurality of injection orders m1 to m3, it is used for the independent operation detection. Independent operation detection can be performed by automatically selecting an injection order that avoids an injection order that matches the resonance order.

  As a result, it is possible to accurately detect the isolated operation of the distributed power supply 28 using the injection order of the fourth order or higher, which has been difficult in the past, and eliminating the influence of the series resonance phenomenon in the power distribution system.

Further, by using an injection order higher than the fourth order, the voltage, impedance or admittance of the injection order component can be obtained without increasing the injection current J _m compared to the case of using the injection order lower than the fourth order. This makes it easier to measure and makes it possible to detect islanding with high accuracy. Therefore, Bun need not to increase the injection current J _m, by reducing the capacity of the current injection apparatus 32, miniaturization thus islanding downsizing of the detection device 30 of the current injection device 32 is enabled.

  Next, another embodiment in which the configuration of the supply stop detection device 34 is changed will be described mainly with respect to differences from the above embodiment.

As the order selector 96 constituting the order selection means, instead of the one that selects one or more injection orders in descending order of the absolute values of the voltages V _{m1 to} V _m3 of the injection orders _{m1 to m3} as in the above example, FIG. As shown in the example shown in FIG. 4, the one that selects one or more injection orders in descending order of the absolute values | Y _m1 |, | Y _m2 |, | Y _m3 | of the admittances of the injection orders _{m1 to m3} may be used. .

Figure order selector 96 in 4 the absolute value _{| Y m1 |, | Y m2} |, | Y m3 | ascending order of the values from the one or more corresponding output E _1, E _2, E ₃ is turned on. Thereby, one or more injection orders m can be selected.

Also in the case of the embodiment using the supply stop detection device 34 shown in FIG. 4, since the injection currents J _m of a plurality of orders m1 to m3 having different orders from the fourth order are injected from the current injection device 32, the injection order m1 ˜m3 happens to coincide with the series resonance order in the power distribution system, and even if the admittance of the coincidence injection order does not become small during the independent operation of the distributed power supply 28, the admittance of other injection orders is scheduled As it gets smaller.

  The supply stop detection device 34 selects one or more injection orders from the plurality of injection orders m1 to m3 in ascending order of the absolute value of the admittance of each injection order and uses it for independent operation detection. Independent operation detection can be performed by automatically selecting an injection order that avoids an injection order that coincides with.

  As a result, it is possible to accurately detect the isolated operation of the distributed power supply 28 using the injection order of the fourth order or higher, which has been difficult in the past, and eliminating the influence of the series resonance phenomenon in the power distribution system.

  Further, as described above, by using an injection order of the fourth or higher order, the capacity of the current injection device 32 can be reduced, and the current injection device 32 can be downsized, and thus the independent operation detection device 30 can be downsized.

Further, since the admittance and the impedance are only in a reciprocal relationship with each other, the impedance Z of each injection order m1, m2, m3 in the arithmetic units 81 to 83 constituting a plurality of determination means, for example, as shown in FIG. _m1, Z _{m @ 2,} Z _m3 respectively calculated according to the following equation, further absolute value thereof _{| Z m1 |, | Z m2} |, | Z m3 | a calculates and outputs a predetermined the comparator 86-88 them compared reference value R _4, and R _5, R _6, respectively, (the absolute value of the impedance) the former is at greater than the latter (the reference value), to turn on the output S _1, S _2, S ₃ respectively You may do it.

[Equation 5]
Z _m1 = V _m1 / I _m1
Z _m2 = V _m2 / I _m2
Z _m3 = V _m3 / I _m3

When the impedances Z _{m1 to} Z _m3 are used as described above, the order selector 96 constituting the order selection means may use voltages V _m1 , V _m2 and V _m3 as in the example shown in FIG. _However , impedances _Zm1 , _Zm2 , and _Zm3 may be used as in the example shown in FIG.

The order selector 96 in FIG. 5 includes one or two or more corresponding outputs E ₁ , E in descending order of the absolute values | Z _m1 |, | Z _m2 |, | Z _m3 | the _2, E ₃ is to turn on. Thereby, one or more injection orders m can be selected.

In the case of embodiments using the supply stop detecting device 34 shown in FIG. 5, since each other orders from the current injection unit 32 4 or more primary injects injection current J _m of different orders m1 to m3, the infusion order m1 Even if there is a coincidence with the series resonance order in the power distribution system within ~ m3 and the impedance of the coincidence injection order does not increase during the independent operation of the distributed power supply 28, the impedance of the other injection orders is expected It grows as expected.

  Since the supply stop detection device 34 selects one or more injection orders from the plurality of injection orders m1 to m3 in descending order of the absolute value of the impedance of each injection order and uses it for isolated operation detection, the series resonance order is selected. Independent operation detection can be performed by automatically selecting an injection order that avoids an injection order that coincides with.

  As a result, it is possible to accurately detect the isolated operation of the distributed power supply 28 using the injection order of the fourth order or higher, which has been difficult in the past, and eliminating the influence of the series resonance phenomenon in the power distribution system.

  Further, as described above, by using an injection order of the fourth or higher order, the capacity of the current injection device 32 can be reduced, and the current injection device 32 can be downsized, and thus the independent operation detection device 30 can be downsized.

Further, as described in Non-Patent Document 1 (see page 948 (62)), monitoring with susceptance, which is a component of admittance, is larger than monitoring with the absolute amount of admittance or impedance. Since the change amount can be used, the susceptance b _{m1 of} each injection order _{m1 to} m3 is used for the determination of the single operation for each injection order m1 to m3 using the calculators 81 to 83 and the comparators 86 to 88. A change amount of ˜b _m3 may be used.

The relationship between the admittance Y _m and the susceptance b _m is expressed by the following equation. Here, g _m is conductance, and j is an imaginary unit. That is, the susceptance b _m is an imaginary part of the admittance Y _m .

[Equation 6]
Y _m = I _m / V _m = g _m + jb _m

The susceptance b _m is obtained by subtracting the induced susceptance from the capacitive susceptance, and is normally a negative value. The susceptance b _m taking a large negative value during the interconnection operation changes to a small negative susceptance b _m during the single operation. Therefore, if a reference value is set between the two, an isolated operation can be detected. To do this, for example, the computing units 81 to 83 in FIG. 3 or FIG. 4 compute and output the susceptances b _m1 , b _m2 , and b _m3 of the respective injection orders m1, m2, and m3 and output them. 86 to 88 may be compared with the intermediate reference value. The order selector 96 may be the one shown in FIG. 3 or FIG. When the order selector 96 shown in FIG. 4 is used, the computing units 81 to 83 may also calculate and use the absolute values of admittances | Y _m1 |, | Y _m2 |, | Y _m3 |.

  In addition, the islanding operation detection device described in Patent Document 1 does not use (a) a plurality of orders of injection orders different from each other in the fourth order or higher, but (b) and from among a plurality of injection orders. In addition, since the injection order that avoids the injection order that coincides with the series resonance in the distribution system is not automatically selected to detect the isolated operation, it is completely different from the isolated operation detection device of the above embodiment.

It is a single line connection figure which shows an example of a power distribution system provided with the isolated operation detection apparatus of the distributed power source which concerns on this invention. It is a circuit diagram which shows an example of the electric current injection apparatus in FIG. It is a block diagram which shows an example of the supply stop detection apparatus in FIG. It is a block diagram which shows the other example of the supply stop detection apparatus in FIG. It is a block diagram which shows the further another example of the supply stop detection apparatus in FIG. It is a model circuit diagram which consists of a square wave voltage generator and a series capacitor. FIG. 7 is a simulation model circuit diagram in which a series resistance is added to the circuit of FIG. 6. It is a figure which shows an example of the square wave voltage waveform in FIG. It is a figure which shows the frequency characteristic of the square wave voltage waveform of FIG. It is a figure which shows an example of the injection current waveform in FIG. It is a figure which shows the frequency characteristic of the injection current waveform of FIG. It is a block diagram which shows an example of the conventional electric current injection apparatus.

Explanation of symbols

2 Host system 4 Substation 10 Distribution line 14 Distributed power supply equipment 18 Service line 28 Distributed power supply 30 Independent operation detector 32 Current injection device 34 Supply stop detection device 50 Square wave voltage generator 52 Capacitor 96 Order selector m1, m2, m3 Injection order J _m Injection current

Claims (7)

A distribution line is connected to a host system via a substation, and this distribution line is applied to a distribution system having a configuration in which a distributed power supply facility having a distributed power source is connected,
A current injection device for injecting, into the lead-in line from the distribution line to the distributed power supply facility, a plurality of orders of injection current having non-integer multiple orders greater than one time of the fundamental wave of the distribution system and different orders. When,
Measure the impedance or admittance of one or more injection orders out of the plurality of injection orders of the distribution system viewed from the power receiving point of the distributed power supply facility, and change the impedance or admittance from the higher system. A supply stop detection device that detects that power supply has stopped, and the current injection device includes a square wave voltage generator that generates a square wave voltage of the non-integer multiple order, and the square wave voltage generation A capacitor connected in series to the output line of the detector and differentiating the square wave voltage from the square wave voltage generator to output a pulsed injection current, the non-integer multiple order, Single operation of a distributed power source characterized by injecting a pulsed injection current containing a plurality of orders of injection current having different orders as components Detection device. A distribution line is connected to a host system via a substation, and this distribution line is applied to a distribution system having a configuration in which a distributed power supply facility having a distributed power source is connected,
A current injection device for injecting, into the lead-in line from the distribution line to the distributed power supply facility, a plurality of orders of injection current having non-integer multiple orders greater than one time of the fundamental wave of the distribution system and different orders. When,
Measure the impedance or admittance of one or more injection orders out of the plurality of injection orders of the distribution system viewed from the power receiving point of the distributed power supply facility, and change the impedance or admittance from the higher system. A supply stop detection device that detects that power supply has stopped, and the current injection device includes a square wave voltage generator that generates a square wave voltage of the non-integer multiple order, and the square wave voltage generation A capacitor connected in series to the output line of the detector and differentiating the square wave voltage from the square wave voltage generator to output a pulsed injection current, the non-integer multiple order, Injecting a pulsed injection current containing a plurality of orders of injection currents of different orders of the fourth order or higher as harmonic components,
The supply stop detection device selects one or more injection orders from the plurality of injection orders in descending order of the voltage value of each injection order in the lead-in line, and changes in the impedance or admittance in the selected injection order From the above, it is detected that the power supply from the host system is stopped. The supply stop detection device includes:
A plurality of determination means for measuring the impedance or admittance of the plurality of injection orders, respectively, and determining for each injection order that the power supply from the host system has been stopped based on a change in impedance or admittance of the injection orders. When,
Order selection means for selecting one or more injection orders in descending order of the voltage value of each injection order in the lead-in line from the plurality of injection orders;
The isolated operation detection apparatus for a distributed power supply according to claim 2, further comprising an enabling unit that validates only an output from the determining unit for the injection order selected by the order selecting unit. A distribution line is connected to a host system via a substation, and this distribution line is applied to a distribution system having a configuration in which a distributed power supply facility having a distributed power source is connected,
A current injection device for injecting, into the lead-in line from the distribution line to the distributed power supply facility, a plurality of orders of injection current having non-integer multiple orders greater than one time of the fundamental wave of the distribution system and different orders. When,
Measure admittance of one or more injection orders among the plurality of injection orders of the distribution system as viewed from the power receiving point of the distributed power supply facility, and power supply from the upper system is stopped due to the change in the admittance A supply stop detection device for detecting that the current injection device is a square wave voltage generator for generating a square wave voltage of the non-integer multiple order, and an output line of the square wave voltage generator. And a capacitor for differentiating the square wave voltage from the square wave voltage generator and outputting a pulse-like injection current, and having the non-integer multiple order and the fourth order or higher. Injecting a pulsed injection current containing a plurality of orders of injection currents of different orders as harmonic components,
The supply stop detection device selects one or more injection orders in order of decreasing absolute value of the admittance of each injection order from the plurality of injection orders, and from the change of the admittance in the selected injection order, An isolated operation detection device for a distributed power source, characterized in that it detects that power supply from a host system has stopped. The supply stop detection device includes:
A plurality of determination means for measuring the admittances of the plurality of injection orders, and determining, for each injection order, that the power supply from the higher-order system has been stopped based on a change in the admittance of each injection order;
Order selection means for selecting one or more injection orders from the plurality of injection orders in order of increasing absolute value of the admittance of each injection order;
5. The isolated operation detection apparatus for a distributed power supply according to claim 4, further comprising an enabling unit that validates only an output from the determination unit for the injection order selected by the order selection unit. A distribution line is connected to a host system via a substation, and this distribution line is applied to a distribution system having a configuration in which a distributed power supply facility having a distributed power source is connected,
A current injection device for injecting, into the lead-in line from the distribution line to the distributed power supply facility, a plurality of orders of injection current having non-integer multiple orders greater than one time of the fundamental wave of the distribution system and different orders. When,
Measure the impedance of one or more injection orders of the plurality of injection orders of the distribution system as viewed from the power receiving point of the distributed power supply facility, and stop the power supply from the upper system from the change in the impedance A supply stop detection device for detecting that the current injection device is a square wave voltage generator for generating a square wave voltage of the non-integer multiple order, and an output line of the square wave voltage generator. And a capacitor for differentiating the square wave voltage from the square wave voltage generator and outputting a pulse-like injection current, and having the non-integer multiple order and the fourth order or higher. Injecting a pulsed injection current containing a plurality of orders of injection currents of different orders as harmonic components,
The supply stop detection device selects one or more injection orders in descending order of the absolute value of the impedance of each injection order from the plurality of injection orders, and from the change in the impedance in the selected injection order, An isolated operation detection device for a distributed power source, characterized in that it detects that power supply from a host system has stopped. The supply stop detection device includes:
A plurality of determining means for measuring the impedance of each of the plurality of injection orders, and determining, for each injection order, that the power supply from the higher-order system has been stopped based on a change in impedance of each injection order;
Order selection means for selecting one or more injection orders in descending order of the absolute value of the impedance of each injection order from the plurality of injection orders;
The isolated operation detection apparatus for a distributed power supply according to claim 6, further comprising an enabling unit that validates only an output from the determining unit for the injection order selected by the order selecting unit.

Images