JPH06315225A - Reverse power relay - Google Patents

Abstract

PURPOSE:To provide a reverse power relay in which the reverse power state can be detected at high speed when a plurality of power supply facilities are operated in parallel without causing erroneous function due to the exciting surge current occurring upon throw-in of a transformer. CONSTITUTION:In the reverse power relay 11 employed in a power supply facility or the power system for power receiving/distributing facility, phase difference phi between input voltage V and input current I from a power system is determined. The input current I is then separated into positive and negative waveform components and positive and negative current values I<+>, I<-> are determined. Subsequently, effective power value P<+> of the positive waveform component is determined based on the voltage value, the phase value, and the positive current value. Furthermore, effective power value P<-> of the negative waveform component is determined based on the voltage value, the phase value, and the positive current value and an operating signal is delivered to the reverse power relay 11 on condition that the ratio of difference between the effective power values P<+>, P<-> of positive and negative waveform components is lower than a predetermined value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reverse power relay device for detecting a reverse power state of a power receiving and distributing facility having a plurality of power supply facilities which can be operated in parallel and are composed of a power transmitting facility or a power generating facility.

[0002]

2. Description of the Related Art Conventionally, there is a system in which a power receiving and distributing facility for operating a private power generator in parallel with a power receiving power source from a power transmitting facility is installed. In such a system, a reverse power relay device is provided at the power receiving point in order to prevent the effective component power obtained as the output of the private power generator from flowing back to the power transmission facility. When a reverse flow of power is detected by this reverse power relay device, the system linkage breaker between the power receiving system from the transmission facility and the private generator system is disconnected to enable effective operation of the private generator system. Has been done.

FIG. 4 is a block diagram of a conventional electric power system provided with a power receiving / distributing facility having a power transmitting facility and a private generator facility. In the figure, 1 is a power transmission facility, and 2 is a private generator facility. A power receiving breaker 3 connects or disconnects the power transmission equipment 1 and the private generator equipment 2. The power from the power transmission equipment 1 obtained through the power receiving breaker 3 is supplied to the load A through the transformer 7 and the transformer secondary breaker 8. Reference numeral 9 is a busbar breaker through which electric power can be supplied to the load B while operating in parallel with the private generator equipment 2. Reference numeral 6 denotes a reverse power relay device provided at the power receiving point of the power receiving and distributing facility, which inputs the current and voltage at the power receiving point through the current transformer 4 and the instrument transformer 5 to convert the power of the private generator facility 2 Detects supply (reverse power) to power transmission equipment.

FIG. 5 is a block diagram of the conventional reverse power relay device 6 shown in FIG. As shown in the figure, the reverse power relay device 6 receives the current I and the voltage V obtained through the current transformer 4 and the instrument transformer 5 provided at the power receiving point of the power receiving and distribution facility. These voltage V and current I are converted into voltage data v and current data i having magnitude and phase corresponding to the voltage V and current I of the system, respectively, by the two converters 6a and 6b used as input means. Reference numeral 6c denotes a pulse transmission control block, which outputs positive and negative square wave pulse signals + P and -P corresponding to positive and negative AC waveforms of the voltage data v as shown in FIG. 6A to the analog switch block 6e.
Call.

The current data i is input to the phase adjustment block 6d, and the current data i ₁ sent from the phase adjustment block 6d is constructed so that it can be phase-corrected with the voltage data v as required. Analog switch block 6e detects the waveform of the current data i to synchronizing pulse signal + P originating from pulsing control block 6c, and -P, and aligned in one direction of the waveform is transmitted as power data W _1. That is, from the pulse signals + P, -P and the current data i, the pulse signal + as shown by the dotted line in FIG.
Positive waveform of current data i synchronized with P and pulse signal −
The negative waveform of the current data i synchronized with P is detected, and
As shown in (c), the waveforms aligned in the same polarity direction are the power data W ₁ . Therefore, the value of the power data W ₁ changes depending on the phase difference from the voltage data v and the value of the current data i. The power data W ₁ is input to the filter block 6f, where it is smoothed and the power data W ₁ shown in FIG.
_It becomes ₂ and is sent to the level detection block 6g.

Reference numeral 6j is an operating power value setting block, the setting value of which is variable. The operating power value data SET W ₂ set by the operating power value setting block 6j is sent to the power level detecting block 6g. Power value level detection block 6g, based on the operating power value setting data SET W _2, performs level detection of the power data W _2. And
As shown in FIG. 6E, when the value of the power data W ₂ is larger than the operating power value setting data SET W ₂ (W ₂ ≧ SET W ₂ ), the level detection signal D ₁ (digital signal) is output to the output block 6h. Send out and output to the outside.

Each of the blocks 6c, 6d, 6e, 6 described above
The power detection means for determining the reverse power state and the magnitude of the detected power value is configured by f, 6g, and 6j. In the external output block 6h, in order to prevent the operation of the reverse power relay 6 due to the transient fluctuation of the power system, a time delay td is added to the output of the operation signal as shown in FIG.
When the level detection signal D ₁ from the level detection block 6g exceeds the time delay td, it is output as an operation signal of the reverse power relay device 6.

[0008]

By the way, in the conventional reverse power relay device 6, when the receiving point breaker 3 of FIG. 4 is turned on and the power of the power transmission equipment 1 is applied to the transformer 7, An exciting inrush current flows due to the iron core saturation. The phase of this exciting inrush current differs depending on the saturation phase of the transformer 7, and may be the same as the reverse power phase. That is, when one of the three phases is saturated, the saturated phase current flows in the opposite direction to the other phase. Which phase is saturated depends on the closing timing of the circuit breaker 3 and is not constant. Therefore,
When the reverse saturated phase current flows through the current transformer 4 to the phase connected to the power relay device 6, the power relay device 6 causes
It operates as in the case of reverse power. Then, the busbar breaker 9 that connects the power transmission facility system 1 and the private generator system 2 is tripped, and the power supply to the load A or the load B is stopped. In order to prevent such a malfunction, it is conceivable to add a long time delay of several seconds to the operation output of the power relay device 6. However, if such a time delay is added, the power transmission equipment 1 in the steady state is added. It is not possible to trip the busbar breaker 9 at a high speed with respect to the reverse flow of electric power.

Next, the operation of the power relay device 6 due to the exciting inrush current when the transformer is turned on will be described with reference to the waveform diagram of FIG. As described above, the exciting inrush current i of the transformer 7 input to the power relay device 6 is generated by the pulse signals + P and -P corresponding to the positive and negative of the voltage v waveform as shown in FIG. 7A. , Are detected as positive and negative waveforms of the shaded portion synchronized with this, and are further converted into electric power data W ₁ aligned in the same direction as shown in FIG. This power data W ₁ is smoothed by the filter block 6f to become power data W ₂ , and the level is detected by the operating power value setting data SET W ₂ . Then, when the value of the power data W ₂ exceeds the operating power value setting data SET W ₂ , the operating signal of the power relay device 6 is output. The magnitude of the exciting inrush current of the transformer 7 may reach about eight times the rated current of the steady transformer in general. On the other hand, since the detected value of the backflow power is set to a value much smaller than the steady power supply power, the probability that the power relay device 6 malfunctions due to the transformer excitation inrush current i is extremely high.

Further, the magnetizing inrush current of the transformer that flows when the transformer on the customer side is turned on is generated when the amount of magnetic flux in the iron core of the transformer exceeds the saturation limit, and the amount of magnetic flux in the iron core is the timing of turning on the transformer. Depending on the situation, a phase current that operates the reverse power relay for receiving power flows. For this reason, the reverse power relay has a problem that it detects apparent reverse power and reacts unnecessarily to erroneously cut off the power receiving breaker.

The present invention has been made in view of the above circumstances, and an object thereof is to cause an undesired response or malfunction in a reverse power state when a plurality of power supply facilities are operated in parallel due to an exciting inrush current when a transformer is turned on. Another object is to provide a reverse power relay device that can detect a high speed without a problem.

[0012]

In order to achieve the above object, claim 1 of the present invention relates to a reverse power relay device provided in a power system of a power supply facility or a power receiving and distributing facility, which is connected to the power system. Voltage value detecting means and current value detecting means for taking in the secondary voltage and secondary current of the instrument transformer and current transformer as input data, and phase difference detecting means for obtaining the phase difference between the input voltage and the input current. , A positive current value detecting means and a negative current value detecting means for respectively separating a positive waveform component and a negative waveform component of the input current, and a voltage value obtained by the voltage value detecting means, the phase difference detecting means, the positive current value detecting means Positive phase active power value detecting means for obtaining the active power value of the positive waveform component from the phase difference and positive current value, and the voltage value, phase difference, obtained by the voltage value detecting means, phase difference detecting means, negative current detecting means, Positive current value to negative waveform Of the negative waveform active power value and the positive waveform active power value detection means and the negative waveform active power value detection means operate, and the ratio of the difference between the detected power values of both is constant. It is characterized by comprising an operation output determination means for performing an operation output of the power relay device on condition that the value is less than or equal to the value. Further, in claim 2, in the reverse power relay device provided in the power system of the power supply facility or the power receiving and distributing facility, the secondary voltage and the secondary current of the instrument transformer and the current transformer connected to the power system are provided. A voltage value detecting means and a current value detecting means which are taken in as input data; a reverse power operation determining means for determining a reverse power operation from the input voltage and the input current; and a positive direction current amount and a negative direction current amount of the input current. The positive direction current amount detecting means and the negative direction current amount detecting means respectively detect the imbalance between the positive direction current amount and the negative direction current amount obtained by the positive direction current amount detecting means and the negative direction current amount detecting means. And a relay operation commanding means for outputting an operation command of the power relay device only when the reverse power operation determining means outputs the power.

[0013]

The present invention focuses on the fact that the excitation inrush current of the transformer contains a large amount of direct current components, so that its waveform is deviated to the positive side or the negative side. When the active power is above the set value level and the ratio of the difference between the detected power values on both the positive side and the negative side is less than a certain value, the operation output is performed, preventing malfunction due to the inrush current of the transformer. Moreover, the reverse power state, which should be detected originally, can be detected at high speed. Moreover, claim 2 detects the imbalance between the current amount on the positive side and the current amount on the negative side, and blocks the operation signal of the reverse power relay on the condition that the amount of imbalance is larger than a predetermined value. The malfunction of the transformer due to the inrush current of the transformer is prevented, and the reverse power state that should be detected is detected at high speed.

[0014]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 shows a reverse power relay device 11 according to an embodiment of the present invention.
2 is a block diagram of the structure, and FIG. 2 shows the active power of the positive waveform component and the active power of the negative waveform component of the magnetizing inrush current of the transformer of FIG. The power system to which the reverse power relay device of this embodiment is applied has the same system configuration as that of FIG. 4 already described.

In the reverse power relay device 11 of FIG.
The input current I and the input voltage V input via the current transformer 4 and the instrument transformer 5 provided at the power receiving point of the power receiving and distribution facility of
Analog / digital conversion element (A / D) 1
Digitally converted via 2 and 13, a voltage detection element (V detection) 14, a phase difference detection element (φ detection) 15, a positive waveform component current detection element (I ⁺ detection) 16, a negative waveform component current detection element (I ^- sent is sampled every predetermined period to detect) 17.

The voltage detecting element 14 calculates the effective voltage value V by calculating the sampling data. Further, the phase difference detecting element 15 calculates the voltage-current sampling data to obtain the phase difference φ between the two. Positive waveform component detection element 1
6. The negative waveform component detecting element 17 calculates the positive and negative waveform sampling data to obtain respective current effective values I ⁺ and I ⁻ .

The respective data of the voltage effective value V, the voltage-current phase difference φ, the positive waveform current effective value I ⁺ , and the negative waveform current effective value I ⁻ are the positive waveform component power detection element (P ⁺ detection) 18 or negative. It is sent to each of the waveform component power detection elements (P ^- detection) 19. The positive waveform component power detection element 18 calculates the following equation from the data of the voltage effective value V ₁ , the voltage-current phase difference φ, and the positive waveform current effective value I ⁺ to obtain the positive waveform component power P ⁺ . P ⁺ = V ・ I ⁺・ cos φ

On the other hand, in the negative waveform component power detection element 19,
The following formula is calculated from the data of the voltage effective value V, the voltage-current phase difference φ, and the negative waveform component current effective value I ⁻ to obtain the negative waveform component power P ⁻ . ^{P - = V · I - ·} cosφ

Positive waveform component power P ⁺ and negative waveform component power P
^-, respectively positive waveform component power operation judgment element (P ⁺ operation judgment) 20, a negative waveform component power operation judgment element (P ^- operation judging) 21, a positive waveform component power P ⁺ and negative waveform component power P ^- power ratio It is sent to each of the differential decision elements 24. The power operation determination elements 20 and 21 for both the positive waveform component and the negative waveform component perform a comparison determination with the operation power PS from the preset operation setting value storage device (SET PS, SET K) 22. Then, the power ratio differential judgment element 24 obtains the ratio of the difference between the positive waveform component power P ⁺ and the negative waveform component power P ⁻ , and stores the detected ratio and the preset operation set value. A comparison determination with the operation ratio K from the device 22 is performed. In the positive waveform component power operation determination element 20, P ⁺
When ≧ PS, the operation signal is sent to the output determination element 23. Similarly, in the negative waveform component power operation determination element 21, P ⁻
When ≧ PS, the operation signal is sent to the output determination element 23.

On the other hand, in the power ratio differential judgment element 24, the ratio (| (P ⁺ −P ⁻ ) / P ⁺ |) of the difference between the positive waveform component power P ⁺ and the negative waveform component power P ⁻ is calculated and this The detection ratio is less than the preset motion ratio K ((| P ⁺ −P ⁻ ) /
When P ⁺ | <K), the operation signal is sent to the output determination element 23.

In the output judging element 23, when the operation outputs of both the positive waveform component power judging element 20 and the negative waveform component power judging element 21 and the operation output of the power ratio differential judging element 24 are all satisfied, the active power is concerned. The operation signal as a relay device is output.

With this structure, as shown in FIG.
The component of the exciting inrush current generated when the transformer is turned on largely deviates to either the positive side (I ⁺ ) or the negative side (I ⁻ ). For this reason, the positive waveform component power P ⁺ and the negative waveform component power P ⁻ are also largely deviated, so that the detected power of either the positive waveform component or the negative waveform component is less than or equal to the set value, and the positive waveform component power P ⁺ and the negative waveform component Since the ratio of the difference between the detected power values of the component power P ⁻ is also the set value or more, it is possible to prevent the operation output of the active power relay device due to the transformer inrush current.

FIG. 3 is a block diagram of another embodiment of the reverse power relay device of the present invention. The power system to which the reverse power relay device is applied has the same system configuration as that of FIG. 4 already described. is there. In the reverse power relay device 30 of FIG. 3, 31 is a positive direction current amount detection element, 32 is a negative direction current amount detection element, 33 is a reverse power element operation element, 34 is an excitation inrush current determination element, 3
5 is an exciting inrush current state detection element, 36 is a NOT element, 3
Reference numeral 7 is an AND element, and 38 is a relay operation command element.

Next, the operation of this embodiment will be described.
In the reverse power relay device 30, the positive direction current amount detecting element 31 and the negative direction current amount detecting element 3 are detected from the input current I input through the current transformer 4 provided at the power receiving point of the power receiving and distribution facility of FIG.
The positive direction current amount B and the negative direction current amount C are separated by 2 respectively, and the positive direction current amount B and the negative direction current amount C are input to the excitation inrush current determination element 34. The excitation inrush current determination element 34 determines that the condition is (B−C) / (B + C) ≧ D, that is, if the unbalance amount of the input current in the positive direction current amount and the negative direction current amount is equal to or more than a predetermined value, the excitation inrush current is determined. . If it is determined that the current is an exciting inrush current, the exciting inrush current state detection element 35 detects the exciting inrush current, and the NOT element 36 inverts it to input it to the AND element 37. At this time, if the output A of the reverse power operation determination element 33 does not exist, the AND element 37 does not hold, so that the operation output of the active power relay device due to the transformer inrush current can be blocked.

However, the output A of the reverse power operation determination element 33 is
Is input to the AND element 37, the AND condition is satisfied, so that the relay operation command element 38 outputs the relay operation command. This is because the reverse power of the originally received power is an AC waveform in which the amount of current in the positive direction and the amount of current in the negative direction are well balanced. Therefore, the reverse power relay device of this embodiment reliably and at high speed during actual reverse power. This is a protection method that can be detected.

[0026]

As described above, according to the present invention, in the power distribution system having a plurality of power supply facilities, the malfunction of the power relay at the time of turning on the transformer and the false disconnection of the system breaker of the power distribution system due to this malfunction. It is possible to prevent the above, and it is possible to detect an abnormal state of the power supply between the power supply facilities in the power distribution system at high speed, and it is possible to improve the stability of the power supply of the power distribution facility.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of an embodiment of a reverse power relay device of the present invention.

FIG. 2 is a waveform diagram showing an example of a general transformer inrush current waveform and voltage waveform.

FIG. 3 is a block configuration diagram of another embodiment of the reverse power relay device of the present invention.

FIG. 4 is a system configuration diagram of a conventional power transmission / reception facility to which the reverse power relay device of the present invention is applied and which has a private power generation facility.

5 is a block configuration diagram of a conventional reverse power relay device used in FIG.

FIG. 6 is a waveform diagram for explaining the operation of each block included in the conventional reverse power relay device of FIG.

7 is a waveform diagram for explaining the operation of the conventional reverse power relay device of FIG.

[Explanation of symbols]

1 ... Power transmission equipment, 2 ... Private generator equipment, 3 ... Power receiving breaker, 4 ... Current transformer, 5 ... Instrument transformer, 6, 11, 30 ...
Reverse power relay device, 7 ... Transformer, 8 ... Circuit breaker, 9 ... Bus line breaker, 12, 13 ... Analog / digital conversion element, 14 ... Voltage detection element, 15 ... Phase difference detection element, 1
6 ... Positive waveform component current detection element, 17 ... Negative waveform component current detection element, 18 ... Positive waveform component power detection element, 19 ... Negative waveform component power detection element, 20 ... Positive waveform component power operation determination element, 21 ... Negative waveform Component power operation determination element, 22 ... Operation set value storage device, 23 ... Output determination element, 24 ... Power ratio differential determination element, 31 ... Positive direction current amount detection element, 32 ... Negative direction current amount detection element, 33 ... Reverse Electric power operation determination element, 34 ...
Excitation inrush current determination element, 35 ... Excitation inrush current state detection element, 36 ... NOT element, 37 ... AND element, 38 ... Relay operation command element.

Claims (2)

[Claims] 1. In a reverse power relay device provided in a power system of a power supply facility or a power receiving and distributing facility, input data of secondary voltage and secondary current of an instrument transformer and current transformer connected to the power system. Voltage value detection means and current value detection means, phase difference detection means for obtaining a phase difference between the input voltage and the input current, and positive current value detection for separating a positive waveform component and a negative waveform component of the input current, respectively. Means and negative current value detecting means, voltage value detecting means, phase difference detecting means, positive current value detecting means for obtaining active power value of positive waveform component from phase difference and positive current value Power value detecting means, the voltage value detecting means, the phase difference detecting means,
Negative waveform active power value detecting means for obtaining active power value of negative waveform component from voltage value, phase difference and positive current value obtained by negative current detecting means, positive waveform active power value detecting means and negative waveform active power value detecting means Both of the means operate and the operation output determination means outputs an operation signal of the power relay device on condition that the ratio of the difference between the detected power values of both means is less than a certain value. Reverse power relay device. 2. In a reverse power relay device provided in a power system of a power supply facility or a power receiving and distributing facility, input data of secondary voltage and secondary current of an instrument transformer and current transformer connected to the power system. Voltage value detection means and current value detection means, reverse power operation determination means for determining reverse power operation from the input voltage and the input current, and positive direction current amount and negative direction current amount of the input current, respectively. The positive direction current amount detecting means and the negative direction current amount detecting means, and the unbalance between the positive direction current amount and the negative direction current amount obtained by the positive direction current amount detecting means and the negative direction current amount detecting means is less than a predetermined value. And a relay operation command means for outputting an operation command of the power relay apparatus only when the reverse power operation determination means outputs.