JP3377776B2 - Islanding detection method and islanding detection device for distributed power supply - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an isolated distributed power source that detects an isolated operation of the distributed power source when the system is stopped by injecting interharmonics having a frequency that is a non-integer multiple of the system fundamental wave into the power system. The present invention relates to an operation detection method and an islanding operation detection device, and more particularly, to avoiding overlapping injection of interharmonics of the same order.

[0002]

2. Description of the Related Art With regard to distributed power sources formed by private power generation facilities of consumers of the electric power system, when the power supply to the substation is interrupted and the system power supply is stopped, the system is operated independently from the system operation. Then, an electric shock or the like occurs due to system charging by this islanding operation, and therefore it is necessary to detect the islanding operation promptly and disconnect from the system promptly.

In order to detect the isolated operation of the distributed power source quickly and reliably on the side of the customer or the like having the distributed power source (hereinafter referred to as the customer side), for example, Japanese Patent Laid-Open No. 10-24.
In Japanese Patent No. 8168 and Japanese Patent Laid-Open No. 11-252806, a frequency m that is a non-integer multiple of the frequency of the system fundamental wave synchronized with the fundamental wave from the consumer side having a distributed power source to the system.
Inject the harmonics of the next order (m is a decimal fraction), measure the harmonics of the injection order of the system on the customer side, and measure the harmonics of the injection order of the system based on this measurement. A distributed power source islanding operation detection device that detects impedance or admittance and detects the stop of system power supply from the change of their magnitude (absolute value) or this change direction (inductive, capacitive) Have been described.

[0004]

When the interharmonics are injected into the electric power system to detect the isolated operation of the distributed power source as described in the above publications, the injection order m is usually on the side of the customer or the like. Is set arbitrarily, and at that time, the order that is less affected by the existing noise of the system (background noise) is selected.

Therefore, when a plurality of customers having distributed power sources are connected to the same system, the order of harmonics m between orders used for detecting the islanding operation is the same among the customers, and a plurality of islanding operations are performed. A situation occurs in which harmonics of the same order and interharmonics are repeatedly injected from the detector.

[0006] In a high voltage system higher than the high voltage distribution system, this double injection also occurs due to the biasing of the distribution banks (integration of the power systems) described below.

That is, as shown in the single line connection diagram of FIG. 3 (a), the bank transformers 3, 3'are connected to the 77 kV upper system 2 drawn from the system power supply (power system fundamental wave power supply) 1.
And when the high-voltage distribution system 5, 5'of two distribution banks of 6.6 kV is connected via the switches 4, 4 ', normally, the switch 6 between the distribution systems 5, 5'is opened. Therefore, the isolated operation detecting devices 7 and 7'of the respective distributed power sources are connected to the power distribution systems 5 and 5 ', and the injection devices 8 and 8'such as their inverters are connected to the systems 5 and 5', for example, 2. Three
Even if the 75th order interharmonics of the same order are injected, their overlapping injection does not occur.

However, when the distribution bank is biased, the switch 4 is opened and the switch 6 is turned on, as shown in FIG. Single bank system 9 with 5 and 5'connected
From the islanding operation detection device 7, 7'to the system 9.
The 375th inter-order harmonics are overlapped and injected.

[0009] Since the distribution banks are repeatedly biased and separated without notifying the customer or the like, the customer or the like cannot know the bias or separation, and Without knowing the above, there occurs a situation in which interharmonics of the same order are redundantly injected into the same system.

The above-mentioned double injection easily occurs even if the interharmonics of different orders are previously assigned to the individual operation detection devices, even if the injection order is set incorrectly on the customer side.

Next, the injection voltage and the injection current in the system when the overlapping injection of the interharmonics of the same order occurs will be described.

For example, in the case of the above-mentioned high-voltage distribution system 5 or 5 ', when the switch 6 is opened as shown in FIG. 3 (a) and the distribution system 5 or 5'is a system of different distribution banks, it is independent. As shown in FIG. 4 (a), the equivalent circuit on the side of the system power supply during the interconnection operation viewed from the operation detection devices 7 and 7'is provided between the power receiving points a and b of the customer and the ground point, respectively. consists bank trans 3,3 ', lines 5,5' and equivalent resistance R _1, R ₂ equivalent coil L _1, L _2, such a configuration connected in series.

At this time, the injection current and injection voltage of the interharmonics injected from the injection device 8 of the islanding operation detection device 7 into the power distribution system 5 are set to I ₁ and V _1, and the injection device of the islanding operation detection device 7'is set. If the injection current and injection voltage of the interharmonic of the same order injected from 8'to the power distribution system 5'are I ₂ and V ₂ , generally, the resistance component of the power system during power feeding is small, and particularly the high voltage power distribution system. In this case, since the system can be regarded as an inductive reactance, the resistors R ₁ and R ₂ are connected to the coil L.
It is sufficiently smaller than the reactances of ₁ and L ₂ , and as shown in FIG. 4B, the phases of the voltages V ₁ and V ₂ lead the phases of the currents I ₁ and I ₂ by slightly less than 90 °. become.

On the other hand, as the distribution bank is biased, the switch 4 is opened and the switch 6 is turned on as shown in FIG. 3B, and the distribution systems 5 and 5'are integrated into the system 9 of the same distribution bank. Then, the equivalent circuit during the interconnection operation has a combined equivalent resistance R and equivalent coil L between the power receiving points a and b and the ground point on the power source side, as shown in FIG. Are connected in series.

At this time, the injection voltage V of the harmonics between orders at the power receiving points a and b becomes the voltage (= V ₁ + V ₂ ) obtained by vector-synthesizing the original injection voltages V ₁ and V ₂ , and the voltage (b) in FIG. ), The phase difference between the injection voltage V and the currents I ₁ and I ₂ is
Depending on the phase difference between the voltage V and the voltages V ₁ , V ₂ , the voltage V ₁ ,
The original phase difference of about 90 ° between V ₂ and the currents I ₁ and I ₂ deviates.

The original injection voltage V₁, V₂Are almost in phase
If the phase difference is around 0 °, the injection voltage V
Input current I₁, I₂Is the same as the original injection voltage V₁, V₂When
Injection current I₁, I₂Almost the same as the phase difference with
Only the magnitude of V is the original voltage V ₁, V₂Doubles.

The impedance of the system in the system can be regarded as an inductive reactance as before the switch 6 is turned on. From the injection voltage V and the injection currents I ₁ and I ₂ , the − induction The sexual reactance can be calculated with twice the original size.

In the case of a system admittance equivalent circuit, since the reciprocal of impedance becomes admittance, the susceptance corresponding to the reactance is 1/2 of the original value from the injection voltage V and the injection currents I ₁ and I _2. The size can be calculated.

When the system power supply is stopped, the system power supply side is in a so-called open state, and at this time, the system impedance (admittance) depends on the system load side condition.

The short-circuit capacity on the system load side is at most about 30% of the short-circuit capacity of the system power supply (for example, 130 MVA), and even when the bank unbalanced system integration occurs, the short-circuit capacity of the system power supply is reduced. Small enough in comparison.

Therefore, if the injection voltages V ₁ and V ₂ are substantially in phase, even if the switch 6 is turned on and the bank bias occurs, when the power supply to the system is stopped, the same as before the bank bias occurs. , The reactance (susceptance) of the system impedance (admittance) changes significantly, and the distributed power source is isolated due to the stop of the system power supply under the same threshold condition as before the occurrence of bank biasing. Driving can be detected and no inconvenience occurs.

Further, when the bank biasing occurs, if independent operation detecting apparatus 7, 7 'injection voltage V _1, V ₂ is substantially opposite phase (phase difference 180 ° back and forth), the voltage V _1, V _{Since the two} cancel each other out, the injection voltage V that is a combination of the voltages V ₁ and V ₂
Is extremely reduced to, for example, 1/3 or less, and disappears in some cases.

In this case, the measured result of the injection voltage V becomes extremely low or difficult even during system interconnection, and as a result, the reactance (susceptance) of impedance (admittance) becomes abnormal. Since it becomes small (large) and becomes a so-called unmeasurable state, it is easily understood that overlapping injection is performed, and overlapping injection can be avoided by changing the injection order or the like.

In other words, when the above-mentioned bank biasing system integration or the like causes overlapping injection of interharmonics of the same order into the system, if system injection is almost in-phase or anti-phase overlapping injection, system power supply is stopped. It is unlikely that a serious error will occur in detecting the islanding operation of each distributed power source.

However, in the case where the injection phase difference of the duplicate injection is not substantially in-phase or anti-phase as described above, it is possible to detect the isolated operation of the distributed power supply due to the stop of the system power supply under the same conditions as before the duplicate injection. Since it is difficult and does not lead to an unmeasurable situation, it is not possible to detect and avoid the occurrence of double injection.

In an actual system, in many cases, overlapping injection with such an intermediate phase difference is likely to occur, and it is important how to detect and avoid overlapping injection at that time. It is one of the challenges.

The present invention reliably detects overlapping injection of interharmonics of the same order into the power system regardless of the phase difference of the overlapping injection, avoids overlapping injection, and detects the isolated operation of the distributed power supply. It is an object of the present invention to provide a detection method and a detection device for performing the above normally.

[0028]

In order to solve the above-mentioned problems, in the isolated operation detection method for a distributed power supply according to claim 1, the impedance of the interharmonic of the injection order of the system or the complex value of the admittance is calculated. Based on the sign condition of at least one of the real part and the imaginary part, or this sign condition and the condition of the size of both parts, the presence or absence of double injection of harmonics between orders of the injection order of the system is determined. Based on this, redundant injection of interharmonics of the same injection order into the system is avoided, and isolated operation of the distributed power supply is detected.

In this case, assuming that the detected impedance (source impedance) and admittance (source admittance) for interharmonics of the injection order (m-th order) of the system are Zm and Ym (= 1 / Zm), Complex values are Zm = rm, where j is the imaginary unit (square root of -1).
+ Jxm (rm is resistance (resistance), xm is reactance), Ym = gm + jbm (gm is conductance, bm is susceptance), and harmonics of the same order from other are not injected into the system.
m and gm are positive, and the imaginary parts xm and bm are negative because the voltage leads the current and becomes in phase.

On the other hand, when the interharmonics of the same order are injected from the other into the system and the interharmonics of the same order are overlapped and injected, for example, the magnitude and phase of the injection voltage in the system change from the time of independent injection. As a result, the real part rm, gm,
The sign condition of the imaginary part xm, bm becomes different from that of the single injection.

Therefore, it is possible to detect the overlapped injection of the interharmonics of the system from the sign condition of at least one of the negative of the real parts rm and gm and the positive of the imaginary parts xm and bm.

Furthermore, considering not only the sign condition but also the condition of the size of the real part rm, gm and the size of the imaginary part xm, bm, it is possible to detect the double injection more accurately.

Then, if the injection point and the measurement point of the interharmonics are set to the power receiving point of the customer of the distributed power source, the duplicate injection of the interharmonics is detected on the customer side of the distributed power source, Based on this detection, it is possible to change the injection order and the like on the customer side to avoid double injection, and normally detect the isolated operation of the distributed power source.

In particular, when the system for injecting the interharmonics is a high voltage system whose real part of the complex value of impedance is equal to or less than the imaginary part and whose voltage is higher than that of the high voltage distribution system, double injection is performed. The sign condition of the discriminant is negative for the real part of the impedance of the interharmonic of the injection order or the complex value of the admittance, and positive for the imaginary part. 1 / imaginary part
It is practical and preferable to be larger than 2.

Next, in the isolated operation detecting device of the distributed power source of claim 4, the injection device for injecting interharmonics into the system and the injection of the system based on the measurement of interharmonics of the injection order of the system An impedance or admittance of harmonics between orders of the order is detected, and a detection processing device that detects an isolated operation of the distributed power supply when the system is stopped from the change of this impedance or admittance is provided, and this detection processing device,
Based on the sign condition of at least one of the real part and the imaginary part of the complex value of the impedance or admittance, or the sign condition and the size condition of both parts, overlapping injection of harmonics between orders of the injection order of the system Is provided, and based on this determination, the above-mentioned islanding operation is detected by avoiding redundant injection of harmonics of the same injection order into the system.

Therefore, it is possible to provide a specific islanding operation detecting device which realizes the detecting method of claim 1.

If an injection device and a detection processing device are installed in a customer having a distributed power source and the power reception point of this customer is the injection point and the measurement point of the inter-harmonic harmonics, the customer side will have the inter-order It is possible to normally detect the isolated operation of the distributed power source by avoiding the redundant injection of harmonics.

Furthermore, a system for injecting interharmonics is
When the size of the real part of the complex value of impedance is equal to or less than the size of the imaginary part and the voltage is higher than the high-voltage distribution system, the sign condition of the overlap injection of the detection processing device is set between the orders of the injection orders. The real part of the complex value of impedance or admittance of the harmonic is negative, and the imaginary part is positive, and the condition of the size of the discrimination of the duplicate injection of the detection processing device is that the real part is larger than 1/2 of the imaginary part. Is practical and preferable.

[0039]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to FIGS. Fig. 1 is a single-line connection diagram of the distribution system, with a substation (distribution S / S) in the upper system 10.
The primary side of a transformer (bank transformer) 12 of 11 is connected, and one or a plurality of distribution lines 14 of a lower system are connected from a secondary side of this transformer 12 via a circuit breaker (bank circuit breaker) 13.
a, 14b, 14c, ... are drawn out, and these distribution lines 1
4a, 14b, 14c, ... Are connected to a general consumer facility 15, a consumer facility 16 having a distributed power source, a general load facility 17, a cogeneration facility 18, and the like.

Then, the power receiving point (the lead-in point) of the distribution line 14a
Assuming that the customer facility 16 connected by A is a customer facility having the distributed power source of the present invention, the customer facility 16 is connected to the power receiving point A via a service line 19 and a circuit breaker 20 and a premises bus 21. One or more transformers 2 on this bus 21
Two or more loads 23 are connected to each of the two.

Further, a distributed power source 27 is connected to the bus bar 21 via a circuit breaker 24 and a circuit breaker 26 for connecting / disconnecting the private power generation equipment 25. When the system is normal, the circuit breaker 2 is connected.
4, 26 are closed, and the distributed power source 27 is connected to the system.

The distributed power source 27 is a combination of a cogeneration system of an AC generator using a rotating machine such as a diesel engine or a gas turbine, or a solar battery, a fuel cell, a wind power generator and an inverse converter (inverter). It consists of a device.

In the event of a system accident, the substation 11
If the circuit breaker 13 is opened and the system power supply is stopped, and the distributed power source 27 continues to operate in a hot line state at this time, the interconnected operation with the system is switched to the isolated operation.

In order to prevent electric shocks to the system due to this islanding operation, the islanding operation of the distributed power source 27 is detected quickly and surely, and the circuit breaker 26 is opened to disconnect the distributed power source 27 from the system. It is necessary to stop the operation of the distributed power source 27.

In order to detect the isolated operation of the distributed power source 27, in this embodiment, the isolated operation detection device 28 for detecting the isolated operation of the distributed power source 27 in the customer facility 16.
To provide.

The islanding operation detection device 28 comprises an injection device 29 for injecting interharmonics into the system, and a detection processing device 30 for detecting the islanding operation of the distributed power source 27.

Further, the power receiving point A is used as the injection point and the measurement point of the interharmonics, and the current transformer 31 and the instrument transformer 32 are connected to the service line 21 side of the circuit breaker 20. Based on the measured voltage of the system fundamental wave, the synchronization control unit 33 of the injection device 29 including a PLL oscillation circuit or the like forms the system fundamental wave synchronization signal.

This synchronizing signal is supplied to an injection power supply unit 34 composed of an inverter or the like, and this injection power supply unit 34 multiplies the synchronization signal by a non-integer multiple to obtain a non-integer multiple of the fundamental wave synchronized with the system fundamental wave. For example, an injection signal of an interharmonic of the order of 2.375 is formed, and an inverter or the like is driven by this injection signal to inject a voltage or current of the interharmonic of the set order. It is supplied to the power receiving point A of the distribution line 14a via 24 and 20.

On the other hand, the detection processing device 30 to which the voltage and current measurement signals of the transformer 32 and the current transformer 31 are supplied is formed of, for example, a microcomputer, and its software causes the injection order (m = 2) of the distribution line 14a. .375), the positive or negative sign condition of at least one of the real part and imaginary part of the complex value of impedance or admittance for interharmonics, or the injection condition of the system from this sign condition and the condition of the size of both parts. Means for determining the presence / absence of overlapping injection of interharmonics is formed and provided, and executes the islanding operation detection flow of FIG.

In step S ₁ of the detection flow, the voltage and current measurement signals are A / D converted to obtain the voltage V (k) and current I (k) at the sampling points k of the system. When the measurement data is obtained, for example, a regression type DFT operation is executed in step S ₂ , and the voltage V at each time point k of the interharmonic of the injection order m represented by the following equation 1 is obtained.
m (k) and current Im (k) are obtained.

[0051]

[Formula 1] Vm (k) = (2 / N) · {Vm (k−1) −
V (k−N) + V (k)} · a ⁻¹ Im (k) = (2 / N) · {Im (k−1) −I (k−
N) + I (k)} · a ^-1

However, N in the equation is the number of time-series samplings used in the DFT operation, and the DFT operation is performed using the measured data of the past N samplings.

The specific value of N is, for example, (64 × 32 =) 2048 sampling numbers obtained by repeating 64 samplings per one cycle of the fundamental wave over 32 fundamental waves of the system. In addition, a is a = exp (-j · 2π · m)
/ N).

Then, the voltage Vm (k) and the current Im (k)
Is a complex value, and in this form, the admittance (power supply admittance) Ym (k) (= gm for harmonics between orders of the injection order m of the system viewed from the power receiving point A
To detect (k) + jbm (k)), step S ₃
From the real part of Im (k) / Vm (k) to the real part of admittance Ym (k), conductance gm (k)
From the imaginary part of Im (k) / Vm (k) to the imaginary part of admittance Ym (k), that is, susceptance bm.
Calculate (k).

At this time, the power system can be regarded as an inductive reactance, and based on the characteristics of this system,
During single injection in which no interharmonics of the same order are injected into the system, the voltage phase advances by less than 90 ° with respect to the current phase, and the real part (conductance gm (k)) of admittance Ym (k) becomes positive. And the imaginary part (Sumptance bm
(K)) becomes negative.

On the other hand, at the time of overlapping injection of interharmonics of the same order, as is apparent from FIGS. 5A and 5B, for example, the magnitude of the injection voltage of interharmonics of the system and The phase changes from the time of single injection, and the conductance gm (k) of the admittance Ym (k) changes from positive to negative or susceptance bm depending on the phase difference between the injection voltage and the injection current.
The sign of (k) changes from negative to positive.

Therefore, when the conductance gm (k) becomes negative or the susceptance bm (k) becomes positive, it is possible to detect overlapping injection of interharmonics of the same order in the system.

Further, in the double injection, for example, the injection voltage is doubled. Therefore, the relationship between the conductance gm (k), the susceptance bm (k) and the size is different from that in the single injection.

When the electric power system is a system of high voltage higher than the high voltage system, for example, "Distributed power supply system interconnection technical guideline" supervised by the Technology Division, Public Utility Division, Agency for Natural Resources and Energy (Nippon Electric Association, 1994) (Issued January 31, 2nd edition), as shown in the calculation example of FIG. 236 on page 118, FIG. 239 on page 126, the impedance to the system fundamental wave (system impedance) per 3 km 0.9
39 + j · 1.065 (Ω), which has a characteristic that the real part is equal to or smaller than the imaginary part, and this characteristic may be applicable to the low voltage distribution system.

In the case of a system having such characteristics, if the impedance of the system fundamental wave is Z = r + jx, then m> 2 = 2
Impedance Z for interharmonics higher than
Since m is Zm = rm + j * xm = r + m * jx, the magnitude of the resistance rm of the real part is 1/2 or less of the magnitude of the reactance xm of the imaginary part (rm <| xm |
/ 2).

The admittance Ym is the reciprocal of the impedance Zm (1 / Zm), and its conductance gm is gm = rm / (rm ² + xm ² ), susceptance b
Since m is bm = −xm / (rm ² + xm ² ),
The magnitude relationship between the conductance gm (k) and the susceptance bm (k) during single injection is 0 <gm (k) ≦ 0.
5 · | bm (k) |

Therefore, this magnitude relationship is not satisfied, and the conductance gm (k) is susceptance bm.
It is larger than 1/2 of (k), and gm (k)> 0.5.
Depending on whether or not | bm (k) |, it is possible to detect and measure the presence or absence of double injection of harmonics between orders of the system.

At least one of the negative conductance gm (k) and the positive susceptance bm (k) is subjected to the overlap injection based on only the sign relation of the positive and negative of the conductance gm (k) and the susceptance bm (k). As a discriminant condition, it may be possible to detect overlapping injection of interharmonics of the same order of the system, but in this form, in order to detect overlapping injection with high accuracy by applying it to a high-voltage distribution system or the like,
The positive and negative sign relationships of both the conductance gm (k) and the susceptance bm (k) and the relationship of the magnitudes thereof are combined, and gm (k) is negative (gm (k) <0) or susceptance bm (k) is Be positive (bm (k)> 0) and that the conductance gm (k) is greater than 1/2 of the susceptance bm (k) (gm (k)> | bm (k) | / 2). , Gm (k) <0, bm (k)> 0, g as a discriminant condition for overlapping injection of interharmonics of the same order in the system.
When any of m (k)> | bm (k) | / 2 continues for a time (predetermined time) for preventing false detection of, for example, about 0.5 seconds, overlapping injection of harmonics between orders of injection order To detect.

Further, since the reverse phase double injection is also detected, the double injection is detected even when the system voltage significantly drops or disappears for a certain period of about 0.5 seconds.

On the other hand, when the breaker 4 of the substation 2 is opened to stop the system power supply and the distributed power source 18 shifts from the continuous operation to the independent operation, the impedance of the system power source becomes extremely large and the susceptance is increased. Since bm (k) greatly changes beyond the set value for islanding detection, it is possible to detect islanding of the distributed power source 18.

Therefore, when the conductance gm (k) and the susceptance bm (k) are calculated in step S ₃ of FIG. 2, the susceptance bm (k) is calculated in step S _4.
It is repeatedly judged whether or not the change from 1 second before is equal to or more than the set value for islanding detection over a certain period, and if the state of the set value or more continues for a certain period, the process proceeds from step S ₄ to step S ₅ . Then, the isolated operation of the distributed power source 18 is detected,
Based on this detection, the circuit breakers 15 and 17 are opened, the operation of the distributed power source 18 is stopped, the distributed power source 18 is disconnected from the system, and the islanding operation is quickly prevented.

During normal interconnection operation, step S ₄
To step S ₆ , and by this step S ₆ ,
The presence / absence of overlapping injection of interharmonics of the injection order is determined based on the positive / negative sign conditions of the conductance gm (k) and the susceptance bm (k), the size condition, and the like.

When it is determined that there is an overlap injection, the process moves from step S ₆ to step S ₇ , in which the overlap injection is notified and the injection order is reselected.

In this reselection, for example, the injection order may be changed little by little until no duplicate injection is detected, and the empty order may be immediately detected to change the injection order.
For example, since it is only necessary to change the injection order of the interharmonic harmonics of the islanding operation detecting device of either one of the two consumers in which the duplicate injection has occurred, the injection of the interharmonic harmonics is temporarily stopped and the other party's injection is performed. It is possible to wait for the order change and then inject the interharmonics of the order again.

By the way, the conductance gm described above is obtained for each high-voltage system in which the advance phase θ of the injection voltage with respect to the injection current of the interharmonic is 85 °, 75 °, and 65 °.
(K), the positive and negative sign conditions of susceptance bm (k),
The result of the following Table 1, Table 2 and Table 3 was obtained by simulating whether or not it is possible to determine the overlap injection based on the condition of the size of gm (k)> (| bm (k) | / 2). .

[0071]

[Table 1]

[0072]

[Table 2]

[0073]

[Table 3]

In these tables, the injection current i1 of the harmonics between orders of the one-sided operation detection device of one consumer in which double injection occurs is i1 = 1.2, and the injection voltage v1 is v1 = exp.
{J · θ · (π / 180)} · 1.2, and the injection current i2 and injection voltage v2 of the harmonics between orders of the other customer's islanding operation detection device in which duplicate injection occurs are In accordance with the above, the magnitudes of the injection currents i1 and i2 are made different, and | i2 | = 1.0 is set for | i1 | = 1.2,
Furthermore, i2 (deg) = exp based on the phase angle variable deg indicating the difference in the injection phase of the interharmonic harmonics between the consumers.
{J · deg · (π / 180)}, v2 (deg) = i
2 (deg) · exp {j · θ · (π / 180)}.

In this case, due to the overlapping injection, the voltage v (deg) of the interharmonic of the injection order in the system becomes v (de).
g) = v1 + v2 (deg), which is the combined voltage, and on the one consumer side, the admittance y1 (deg) of the interharmonics of the injection order of the system is y1 (deg) = i1 / v (d).
ig), and on the other side of the customer, the admittance y2 (deg) of the harmonics between orders of the injection order of the system
Can be obtained from the calculation of y2 (deg) = i2 (deg) / v (deg).

In order to simplify the explanation, the current i1,
i2 (deg) and voltages v1, v2 (deg) and the like are arbitrary units.

In each table, the admittance y1
The imaginary number unit j of (deg) and y2 (deg) is indicated by i.

Further, "duplication detection" in each table indicates whether duplicate injection can be detected, ◯ indicates yes, and x indicates no.

When the phase angle in Table 1 is 85 °, i1
= 1.2, v1 = exp {j · 85 · (π / 180)}
・ 1.2, i2 (deg) = exp {j · deg · (π
/ 180)}, v2 (deg) = i2 (deg) · ex
p {j · 85 · (π / 180)}, and from the admittance y2 (deg), the variables deg = 0 °, 10 °,
Overlapping injection can be discriminated except for the cases of 20 °, 30 °, and 40 °, and from the admittance y1 (deg),
Variable deg = 0 °, 10 °, 180 °, 320 °, 33
Overlapping injection can be discriminated except at 0 °, 340 ° and 350 °.

In this case, the overlap injection is performed from at least one of the admittances y1 (deg) and y2 (deg), except when the phase difference of the overlap injection represented by the variable deg is near 0 ° of 0 ° and 10 °. Can be determined.

Next, in the case of the phase angle of 75 ° in Table 2, i1
= 1.2, v1 = exp {j · 75 · (π / 180)}
・ 1.2, i2 (deg) = exp {j · deg · (π
/ 180)}, v2 (deg) = i2 (deg) · ex
p {j · 75 · (π / 180)}, and from the admittance y2 (deg), the variable deg = 0 °, 10 °, 2
Overlapping injection can be discriminated except at 0 °, 340 °, and 350 °, and from the admittance y1 (deg), the variables deg = 0 °, 10 °, 20 °, 30 °, 18
Overlapping injections can be distinguished except at 0 ° and 340 °, 350 °.

Also in this case, the phase difference of the overlapping injection is 0 °, 1
Admittances y1 (deg), y2 (de) are excluded except in the case of 0 °, 20 °, 340 °, and 350 ° near 0 °.
Overlapping injections can be identified from at least one of g).

Further, in the case of the phase angle of 65 ° in Table 3, i1
= 1.2, v1 = exp {j · 65 · (π / 180)}
・ 1.2, i2 (deg) = exp {j · deg ・
(Π / 180)}, v2 (deg) = i2 (deg) ·
exp {j · 65 · (π / 180)}, and adm = 0 ° and 320 ° from the admittance y2 (deg).
Admittance y1 (deg) except for ~ 350 °
From, it is possible to discriminate overlapping injections except in the case of deg = 0 ° to 50 ° and 180 °.

Therefore, in this case, the admittance y1 is excluded unless the injection is performed in the same phase of deg = 0 °.
Overlapping injection can be discriminated from at least one of (deg) and y2 (deg).

That is, as is clear from Table 1, Table 2 and Table 3, when the discrimination is made from the sign condition and the size condition of the present invention, the phase difference of the overlap injection is limited to around 0 °. Except when the double injection is performed, it is possible to detect the duplicate injection by at least one of the independent operation detecting devices of both customers.

If the overlap injection is almost in phase near 0 °, there is no inconvenience even if the detection of the isolated operation is continued in the overlap injection state. Except for this overlap injection in phase, when overlap injection occurs It is possible to avoid this double injection.

Therefore, for example, when the power systems are integrated in a hot line state and the islanding operation detection devices 28 such as a plurality of consumers are connected to the same system by, for example, bank biasing, the interharmonics of the same order are intermixed. It is possible to reliably detect overlapping injection of an intermediate phase difference that is not in-phase or opposite-phase of the waves, avoid overlapping injection, and normally detect independent operation of each distributed power supply 27.

Further, even if duplicate injection of interharmonics of the same order occurs due to a setting error on the side of the customer or the like, this duplicate injection can be reliably detected and avoided.

In the above-mentioned form, the admittance Ym
Although the overlap injection is detected from (k), it is needless to say that the overlap injection can be similarly detected from the impedance Zm (k) which is the reciprocal of the overlap injection.

When the detection process is simplified, etc.,
Impedance Zm (k) or admittance Ym (k)
The presence / absence of duplicate injection may be determined only based on the positive / negative sign condition of at least one of the real part and the imaginary part of.

Further, as in the above-mentioned embodiment, the overlap injection is performed from the positive and negative sign conditions of the real number part and the imaginary number part of the complex value of the impedance Zm (k) or the admittance Ym (k) and the condition of the size of both parts. When determining the presence / absence, the condition for the size of the presence / absence may be set appropriately according to the characteristics of the system, and is not limited to the condition greater than 1/2 of the above-mentioned embodiment.

Further, in the above embodiment, the injection point and the measurement point of the interharmonics are set to the power receiving point A, but the injection point and the measuring point may be different, and they are provided in addition to the power receiving point A of the customer. May be.

The present invention can, of course, be applied to detection of isolated operation of distributed power sources of various electric power systems.

[0094]

The present invention has the following effects. First, in the case of the islanding operation detection method according to claim 1, the positive / negative sign condition of at least one of the real part and the imaginary part of the impedance of the interharmonic of the injection order of the system or the complex value of the admittance, or this sign condition Based on the size conditions of both parts, it is determined whether or not there is overlapping injection of harmonics between orders of the injection order of the system, and based on this determination, overlapping injection of harmonics between orders of the same injection order to the system is avoided. Distributed power source 2
Since the isolated operation of No. 7 is detected, even if the injection phase of the duplicate injection is other than substantially the same phase or the opposite phase, the duplicate injection can be reliably detected and avoided, and the isolated operation of the distributed power source 27 can be accurately detected. Can be done.

Further, in the case of claim 2, since the injection point and the measurement point of the interharmonics are set to the power receiving point A of the customer having the distributed power source 27, the customer side is carried out in the same manner as in claim 1. It is possible to obtain the same effect as in claim 1 by detecting the overlapping injection of harmonics between orders and avoiding the overlapping injection based on this detection.

Further, in the third aspect of the present invention, the system for injecting the interharmonics is a system of high voltage higher than the high voltage distribution system in which the size of the real part of the complex value of impedance is less than the size of the imaginary part. A specific method of detecting duplicate injections, which is sometimes useful, can be provided.

Next, in the case of the isolated operation detecting device of the distributed power source of claim 4, the injection device 29 and the detection processing device 30 are provided.
This detection processing device 30 is provided with a positive / negative sign condition of at least one of a real part and an imaginary part of a complex value of impedance or admittance of interharmonic of the injection order of the system, or this sign condition and both parts. From the size condition,
A distributed power source 2 is provided with means for determining whether or not there is overlapping injection of harmonics between orders of injection order of the system, and based on this determination, overlapping injection of harmonics between orders of the same injection order to the system is avoided.
Since the islanding operation of No. 7 is detected, it is possible to provide a specific islanding operation detecting device that realizes the detection method of claim 1.

Then, the injection device 29 and the detection processing device 3
It is practical and preferable that 0 is provided in a customer who has the distributed power source 27, and the power receiving point A of this customer is the injection point and the measurement point of the interharmonics.

Furthermore, a system for injecting interharmonics is
When the size of the real part of the complex value of the impedance is equal to or less than the size of the imaginary part and the voltage is higher than the high-voltage distribution system, the sign condition of the determination of the duplicate injection of the detection processing device 30 is set between the orders of the injection orders. The real part of the complex value of impedance or admittance of the harmonic is negative, and the imaginary part is positive, and the condition of the size of the discrimination of duplicate injection of the detection processing device 30 is that the real part is less than 1/2 of the imaginary part. It is preferable to make it large.

[Brief description of drawings]

FIG. 1 is a single line connection diagram of an embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of FIG.

3 (a) and 3 (b) are single-line connection diagrams before and after integration by bank biasing of a high-voltage system.

4A and 4B are an equivalent circuit diagram and a voltage / current vector diagram before integration by biasing banks of a high-voltage system.

5 (a) and 5 (b) are an equivalent circuit diagram and a vector diagram of voltage and current after integration by bank offset of a high voltage system.

[Explanation of symbols]

10 Upper system 14a, 14b, 14c Distribution line 27 Distributed power supply 29 injection device 30 Detection processing device A power receiving point

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Masakuni Asano 47 Umezu Takaune-cho, Ukyo-ku, Kyoto City Nissin Electric Co., Ltd. (72) Inventor Shoji Nishimura 47 Umezu Takaune-cho, Ukyo-ku, Kyoto Nisshin Electric Co., Ltd. In-company (72) Inventor Yoshifumi Minowa 47 Umezu Takaune-cho, Ukyo-ku, Kyoto City Nissin Electric Co., Ltd. (56) References JP-A-11-136865 (JP, A) JP-A-2000-270482 (JP, A) JP-A 2001-298866 (JP, A) JP-A 61-12824 (JP, A) JP-A 4-67727 (JP, A) JP-A 11-252806 (JP, A) JP-A 10-248168 ( JP, A) JP 58-182428 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H02J 3/00-5/00

Claims (6)

(57) [Claims] 1. Injecting interharmonics into a system, detecting impedance or admittance of interharmonics of the injection order of the system based on measurement of interharmonics of the injection order of the system, the impedance Alternatively, in the isolated operation detection method of the distributed power supply detecting the isolated operation of the distributed power supply from the change of the admittance at the time of system shutdown, the positive or negative sign of at least one of the impedance or the complex value real number part of the admittance complex value The presence or absence of overlapping injection of interharmonics of the injection order of the system is determined based on the condition, or the sign condition and the condition of the size of both parts, and based on the determination, the interharmonics of the same injection order. The method for detecting isolated operation of a distributed power source, characterized in that the isolated operation is detected by avoiding duplicate injection into the system. 2. The isolated operation detection method for a distributed power supply according to claim 1, wherein the injection point and the measurement point of the interharmonics are the power reception point of the customer having the distributed power supply. 3. A system for injecting interharmonics is a system for high voltage, which is higher than a high-voltage distribution system, in which the size of the real part of the complex value of impedance is less than the size of the imaginary part, and the overlap injection is discriminated. The sign condition of is a negative value for the real part of the complex value of impedance or admittance of the interharmonic of the injection order, and a positive value for the imaginary part, and the condition of the discriminative magnitude of the duplicate injection is that the real part is 3. The isolated operation detection method for a distributed power source according to claim 1, wherein the imaginary number part is set to be larger than ½. 4. An injection device for injecting interharmonics into the system, and detecting impedance or admittance of interharmonics of the injection order of the system based on measurement of interharmonics of the injection order of the system, And a detection processing device for detecting an isolated operation of a distributed power supply from a change in the impedance or the admittance when the system is stopped, the detection processing device, at least a real part of the complex value of the impedance or the admittance, an imaginary part Means for determining the presence or absence of overlapping injection of harmonics between orders of the injection order of the system based on one of the positive and negative sign conditions, or the sign condition and the condition of the magnitudes of both parts, based on the judgment, The isolated operation of the distributed power supply, characterized in that the isolated operation is detected by avoiding the overlapping injection of interharmonics of the same injection order into the system. Detection device. 5. The injection device and the detection processing device are provided in a customer having a distributed power source, and the power reception point of the customer is used as an injection point and a measurement point of harmonics between orders.
An isolated operation detection device for the distributed power supply described. 6. The system for injecting the interharmonics is a high voltage system having a real part of impedance complex values less than an imaginary part and having a higher voltage than a high voltage distribution system. The sign condition of the injection discrimination is negative for the real part of the impedance of the interharmonic of the injection order or the complex value of the admittance, and positive for the imaginary part, and the size of the discrimination of the duplicate injection of the detection processing device is large. 6. The islanding operation detection device for a distributed power source according to claim 4, wherein the real number part is set to be larger than 1/2 of the imaginary part.