JPS649816B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to network power receiving equipment, and particularly relates to network power receiving equipment, and in particular, to problems caused by incorrect or disconnected protectors or disconnectors when regenerative power is generated from a load that generates regenerative power (hereinafter referred to as a regenerative power generating load). The present invention relates to network power receiving equipment that prevents

Recently, highly reliable spot network power receiving equipment has been adopted for concentrated loads with high load density in buildings and the like. Figure 1 shows an example of the circuit of such network power receiving equipment. In the figure, 1 is a substation, 2 _A to 2 C are distribution line disconnectors, and 3 _A to 2 _C are distribution line disconnectors.
3 _C is the distribution line, 4 _A to 4 _C are the transformer primary side disconnectors,
5 _A to 5 _C are feeders, 6 _A to 6 _C are network transformers, 7 _A to 7 _C are protectors and disconnectors, 8 _A to 8 _C
1 is a protector fuse, _9A to _9C are network relays, 10 is a network busbar, and 11 is a load. Note that the circuit example shown in Figure 1 has five feeders.
Although it has three lines consisting of _A to _5C , it is possible to form a network circuit with two or more lines, and it goes without saying that there are various numbers of lines.

When the system is operating normally in the network circuit shown in Figure 1, power from substation 1 is transferred from distribution lines _3A to _3C to feeders _5A to _5C and network transformers _6A to _6C. It is supplied to the load 11 through the. However, for example, if an accident occurs at point A of distribution line _3B or point B of feeder _5B , the distribution line disconnector _2B at substation 1 automatically disconnects the distribution line and disconnects the distribution line. 3 _B and feeder 5 _B are connected from other distribution lines 3 _A and 3 _C to feeders 5 _A , 5 _C and network transformers 6 _A and 6 _C and network transformer 6.
Power is reversely transmitted from the network bus 10 side through _B. Network relays _9A to _9C all have the function of detecting the direction of power, and when reverse power is detected, they output an output and switch to the protector or disconnector _7A.
~7 _C is starting to operate intermittently. Therefore, if an accident occurs on the distribution line _3B or the feeder _5B as described above and power is reversely transmitted to the network transformer _6B from the network bus 10 side, the protector and disconnector _7B to prevent the fault current from flowing to the fault point. When the accident at point A or B is a short circuit, the reverse power that passes through the protector and the disconnector is sufficiently large, but if the accident is a ground fault, the power that passes through the protector and the disconnector is large enough. is a relatively small amount of power, which is the sum of the transformer reverse excitation current of the line, the feeder reverse charging current, and the ground fault current reversely supplied from the network bus side. Network relays have the function of detecting not only the large reverse power that occurs in short-circuit accidents, but also the small reverse power that occurs in ground faults and the like.

By the way, when such network power receiving equipment is applied to building power receiving equipment, loads such as elevator motors that generate regenerative power when the elevator starts and stops will be connected to the network busbar, and this When the elevator is operated when the power receiving equipment is under a light load, the regenerated power of the elevator motor, which is a relatively small input to the network relay, flows out from the network bus bar toward the feeders _5A to _5C , and therefore each Network relays _9A to _9C operate simultaneously, causing protector and disconnection 7
There is a risk that _A to _7C will be cut off and the network bus 10 will be completely out of power. In order to prevent the accidental disconnection and operation of protectors and disconnectors caused by such regenerative power, conventionally a pseudo load that absorbs regenerative power is temporarily or permanently connected to the network bus bar, etc., and the load is connected to the feeder. A method has been considered to prevent the leakage of power, but this method has the disadvantage of increasing unnecessary power loss. In addition, when relatively small reverse power such as regenerative power occurs, there is a method of delaying the output of the network relay so that the protector or disconnector does not disconnect while the regenerative power continues. . In this method, only a relatively small amount of power flows back, as in a ground fault, but it is clearly an accident.
Even if it should be disposed of promptly for security reasons,
Since the input to the network relay is small, the protector and disconnector cannot be disconnected immediately, and there is a drawback that it takes time to complete the accident handling. Furthermore, the output of each network relay is compared with a logic circuit,
When all network relays detect regenerated power, such as when regenerated power is generated, there is a method to prevent the protector or disconnector from opening or disconnecting.
This method assumes that the regenerated power passes through each protector and disconnector almost uniformly, and if the impedance of each line is uneven, the reverse amount of regenerated power will become uneven, and the network There are some circuits that do not have the operating sensitivity of relays, and there is a problem that malfunctions of protectors and disconnectors cannot be reliably prevented.

The present invention prevents a complete power outage of the load by preventing the protector and disconnector from opening or disconnecting when reverse power is generated due to regenerative power, and also prevents a complete power outage of the load when reverse power is generated due to an accident. We have proposed highly reliable network power receiving equipment that can immediately shut off the protector or disconnection even when the power is off.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The network power receiving equipment of the present invention will be described in detail below with reference to drawings showing embodiments.

FIG. 2 is a single line diagram of the network power receiving equipment according to the present invention, and FIG. 3 is a block diagram showing the configuration of a network relay used in the network power receiving equipment according to the present invention.

In Figure 2, 5 _A to 5 _C are feeders, 6 A to 5 C are feeders, and 6 _A to 5 C are feeders.
6 _C is a network transformer connected to each of the feeders 5 _A to 5 _C , and 7 _A to 7 _C is a network transformer connected to the low voltage side of each of the network transformers 6 _A to 6 _C and the network bus 1.
Protector and disconnector connected between 0 and 11
is the general load connected to the network bus 10,
_90A to _90C are the lines between the protector shield disconnectors _7A to _7C and the network transformers _6A to _6C , and the lines between the network busbar and the protector shield disconnectors _7A to _7C. The voltage and current transformer CT _A ~ CT _C and transformer PT _o
and PT _A to PT _C , determines the power direction, and issues an output, and controls the opening and closing of the protector and disconnectors 7 _A to 7 _C. M is an elevator motor connected to the network bus 10. Or a regenerative power generating load that generates regenerative power such as an induction motor,
13 detects the current and voltage of the load line 14 (or the current of the load line 14 and the voltage of the bus 10) to which the regenerative power generation load is connected using the current transformer CT _L and the transformer P _O , and converts the reverse voltage from the load. This is a reverse power relay that determines the presence or absence of power and generates a first reverse power detection signal when reverse power is detected, and these constitute a network power receiving facility. The output of the reverse power relay 13 is connected to the network relay _90A to 90A.
0 _C , network relay 90 _A ~ 90
The protector and disconnector _7A are activated by each output of _C.
~7 It is designed to allow _C to be turned on or off.

Each of the network relays _90A to _90C is constructed as shown in FIG. 3, and the same parts in FIG. 3 as those in FIG. 2 are given the same reference numerals. Note that FIG. 3 shows the configuration of a network relay _90A provided in a feeder _5A as an example. In Figure 3,
Network relay 90 _A is relay basic part 901
and a relay suppressing section 902. The relay basic section 901 includes a differential voltage/phase difference detection circuit 20, a no-voltage detection circuit 21, a reverse power detection circuit 22, and an OR circuit 23. Input terminals 20a, 20 of differential voltage/phase difference detection circuit 20
b is connected to voltage input terminals 24, 24' to which the output sides of transformers P _A and P _O are connected. Further, the voltage input terminal 24' is connected to the input terminal 21a of the no-voltage detection circuit 21.
output terminal 21b and differential voltage/phase difference detection circuit 2
The output terminal 20c of 0 is connected to the input terminals 23b and 23a of the OR circuit 23, respectively, and the output terminal 20c of the OR circuit 2
The output terminal 23c of No. 3 is connected to the closing command terminal 25 of the protector and disconnector. Furthermore, the voltage input terminal 24' is also one input terminal 22a of the reverse power detection circuit 22 which outputs a second reverse power detection signal when reverse power from the network bus side is detected.
The other input terminal 22b is connected to the first connection terminal 26. The output terminal 22c of the reverse power detection circuit 22 is connected to the second connection terminal 2.
7 and an output terminal 2 that outputs a second reverse power detection signal.
8.

The relay suppression unit 902 includes an overcurrent detection circuit 29 that outputs an overcurrent detection signal when an overcurrent is detected.
, AND circuits 30 and 31, a NOT circuit 32, and an OR circuit 33. The input terminal 29a of the overcurrent detection circuit 29 is connected to the current input terminal 34 connected to the output side of the current transformer CT _A , and the first relay terminal 34 connected to the first connection terminal 26. 'It is connected to the.

The output terminal 29b of the overcurrent detection circuit 29 is connected to one input terminal 30a of the AND circuit 30, and the other input terminal 30b of the AND circuit 30 is connected to the second input terminal 30a of the AND circuit 30.
It is connected to the second relay terminal 35 which is connected to the connection terminal 27 of. An output terminal 30c of the AND circuit 30 is connected to a shear cut command signal output terminal 36, and is also connected to one input terminal 33a of an OR circuit 33. A third relay terminal 37 connected to the output terminal 28 that outputs the second reverse power detection signal is one input terminal 31a of the AND circuit 31.
is connected to the other input terminal 3 of the AND circuit 31.
1b is connected to a welt breakage prevention input terminal 38 via a knot circuit 32. A first reverse power detection signal from the reverse power relay 13 is applied to the shingle interruption prevention input terminal 38 . Also, AND circuit 31
The output terminal 31c of is connected to the other input terminal 33b of the OR circuit 33, and the output terminal 33c of the OR circuit 33 is connected to the shear break command output terminal 39 of the protector and disconnector. Then, the output from this output terminal 39 causes the protector and disconnector _{7A to}
can be operated on and off. Note that the first and second connection terminals 26 and 27 and the output terminal 28 that outputs the second reverse power detection signal, and the first to third relay terminals 34', 35 and 37 can be connected and disconnected. The relays are connected by appropriate means such as a flexible connector or a crossover connection using an appropriate connection line, and these constitute a network relay. Then, network relays _90B , 90B installed in other feeders _5B , _5C shown in FIG.
_90C also has the same structure as the network relay _90A described above.

In this embodiment, the AND circuit 31 and the NOT circuit 32 convert the first reverse power detection signal (signal from the reverse power relay 13) and the second reverse power detection signal (signal from the reverse power detector 22). As an input, when the second reverse power detection signal is generated in a state where the first reverse power detection signal is not generated, the first reverse power detection signal is commanded to immediately disconnect the protector or the disconnector.
A first command circuit is configured that commands to prevent the protector and the disconnector from breaking when the reverse power detection signal and the second reverse power detection signal are generated at the same time. Further, the AND circuit 30 and the OR circuit 33 input the second reverse power detection signal and the overcurrent detection signal, and when both signals are generated at the same time, the protector and the disconnector are operated independently of the command from the first command circuit. A second command circuit is configured to give a command to immediately cut off the power supply.

Network relay 90 configured as described above
In the network power receiving equipment configured as shown in Fig. 2 using _A to _90C and reverse power relay 13, when the regenerative power generation load M does not generate regenerative power and is in a normal operating state, the reverse power relay power relay 1
No. 3 does not detect reverse power and is in an inactive state. In addition, the differential voltage/phase difference detection circuit 20 and the no-voltage detection circuit 21 of the network relays _90A to _90C do not have the specified input, so there is no output, and the closing command output of the protector and disconnectors _7A to _7C is performed. However, the protector and disconnectors _7A to _7C remain closed. On the other hand, the reverse power detection circuit 22 and the overcurrent circuit 29 also do not have predetermined inputs and do not output any output. In addition, there is no output from the reverse power relay 13, and there is no output from the disconnection command output terminal 39, and the protectors and disconnectors _7A to _7C remain in the closed state.

Therefore, if an accident occurs in the feeder _5A connected to the high voltage side of the network transformer _6A , the distribution line installed on the substation side of the distribution line (not shown) connected to this feeder _5A The breaker operates quickly, and the fault current from the substation to the fault point is quickly cut off. However, fault current is supplied to the fault point from the healthy feeders _5B and _5C through the network bus 10 and network transformer _6A . Therefore, the network relay 90 _A connects the transformer PT _o and the current transformer
Based on the output signal from CT _A , the reverse power detection circuit 22 detects the occurrence of reverse power and issues a second reverse power detection signal, which is applied to the AND circuits 30 and 31, but since the reverse power is due to an accident. Since the reverse power relay 13 is not operating, there is no input at the fault blocking input terminal 38, and therefore, there is an input at the other input terminal 31b of the AND circuit 31 via the knot circuit 32. Also, one input terminal 31a of the AND circuit 31
A second reverse power detection signal from the reverse power detection circuit 22 is added to the AND circuit 31, which outputs an output, passes through the OR circuit 33, and outputs a shear cut command output to the shear cut command output terminal 39. As a result, the protector shear cutter _7A is immediately cut off. That is, in the present invention, even if the value of the fault current is small, in the event of an accident, the protector and disconnector _7A connected to the fault point are immediately disconnected. If the fault current is large, the input terminals 30b of the AND circuit 30,
Since the second reverse power detection signal and the overcurrent detection signal from the overcurrent detection circuit 29 are applied to 30a, a command signal is generated from its output terminal 30c, and the OR circuit 33
A sheath breaker command output is outputted to the shear breaker command output terminal 39 via the sheath breaker command output terminal 39, and the protector sheath breaker _7A is instantly ruptured with a shear breaker command output different from the output from the AND circuit 31.

By the way, when regenerative power is generated from the regenerative power generation load M while the network power receiving equipment is operating normally, the reverse power is immediately detected by the reverse power relay 13, and its output is simultaneously transmitted to each network. It is applied to the shingle breakage prevention input terminal 38 of the workpiece relays _90A to _90C . As a result, there is no input to the input terminal 31b of the AND circuit 31 of each of the network relays _90A to _90C , and the AND circuit 31 is locked in a state in which it does not output any output.

On the other hand, the reverse power due to regenerative power is generated by current transformer CT _A ~
Network relay 9 detected by CT _C respectively
0 _A to 90 _C is added to the reverse power detection circuit 22 and overcurrent detection circuit 29, but since the reverse power due to regenerative power, that is, the current in the opposite direction is small, the overcurrent detection circuit 29 does not operate and does not output. . Therefore, one input terminal 30a of the AND circuit 30 has no input;
Even if the output from the reverse power detection circuit 22 is applied to the other input terminal 30b, the AND circuit 30 does not generate an output. Therefore, there is no input to the OR circuit 33, and therefore no protector disconnection command output is issued.
Therefore, simultaneously with the generation of regenerated power, the disconnection command outputs of each of the network relays _90A to _90C are locked, thereby preventing the protector or the disconnector from being erroneously turned on or disconnected due to the generation of regenerated power.

In FIG. 2, the reverse power relay 13 is provided in the middle of the circuit that connects only the regenerative power load M, but the present invention
It can also be applied to the case where these are connected as shown in FIGS. 4 and 5. 2 in Figures 4 and 5.
Components corresponding to those shown in the figures are designated by the same reference numerals.

In FIG. 4, a plurality of general loads 11 and regenerative power loads M are commonly connected to a load-side bus 1, and this load-side bus 1 is connected to a network bus 10.
and is connected by load connection line l'. A current transformer CT _L is provided on the load connection line l', a transformer P _O is provided on the bus 10 (or the load tangent line l'), and their outputs are provided to the reverse power relay 13. In this case, when the general load 11 is large, the regenerative power generated from the regenerative power generation load M will be supplied to the general load 11, and the reverse power passing through the load connection line l' will decrease, and the reverse power relay 13 operation frequency can be reduced.

In FIG. 5, a plurality of general loads 11 and a plurality of regenerative power generating loads M are directly connected to a network bus 16 by load connection lines _l1 to _l4 , respectively. And each load connection line _l1 to _l4 has a current transformer.
CT _L is provided, and the secondary winding of each current transformer CT _L is connected to a plurality of input windings W ₁ to W ₄ wound around the annular core C of the current combining current transformer TCT. The output winding W ₀ wound in the reverse power relay 13
The reverse power relay 13 is connected to the reverse power relay 13 so as to add to the power. A transformer P _o is also provided on the network bus 10 and its output is connected to a reverse power relay 13 . In this case each load connection line
Since the reverse power relay 13 is controlled by the output of the vector-synthesized sum of the currents passing through l ₁ to l ₄ , rational control is performed that takes into account the power for the general load and the reverse power due to the regenerative power generation load. be able to.

In this embodiment, feeders 5 _A , 5 _B , 5
Although three lines _(C ) are used, it is of course possible to implement the present invention without being limited to the number of lines as long as there are two or more lines. Also, an AND circuit 31 and a NOT circuit 32
Although these are provided separately, they may be provided as one NAND circuit. Furthermore, as the reverse power relay, relays such as a power direction relay and a reactive power direction relay can be used.

As described in detail above, the network power receiving equipment of the present invention uses the network relay and the reverse power relay that detects the reverse power of the load and outputs the first reverse power detection signal. When the second reverse power detection signal is generated from the reverse power detection circuit, a command is immediately issued to shut off the protector or disconnector, and when the first and second reverse power detection signals are present at the same time. issues a command to prevent the protector or disconnector from disconnecting, and if the second reverse power detection signal and the output of the overcurrent detection circuit are present, the protector or disconnector is unconditionally activated. Since it is configured to issue a command to shut off, if reverse power due to regenerated power is not detected, the protector or disconnector can be shut off immediately even in the event of an accident in a small current range. Furthermore, when the reverse power of the regenerative power generation load is detected, it is possible to lock the cutting operation of the protector and the disconnector, thereby preventing unnecessary cutting and cutting of the protector and the disconnector. Furthermore, when a large current reverse power is generated due to an accident, the protector or disconnector can be immediately shut off regardless of whether the reverse power is detected from the regenerative power load. Therefore, even if a serious accident occurs in which a large current flows at the same time as regenerated power is generated, the protector or disconnector can be quickly disconnected and the point of failure can be isolated immediately. In addition, it is possible to reliably prevent protector and disconnection errors and disconnections caused by uneven interlock conditions that occur when the magnitude of reverse power due to regenerative power is uneven on each line. If a relatively small current accident occurs when no power is being generated, the protector or disconnector can be immediately turned off, eliminating delays in handling the accident. It has completely superior advantages,
It is possible to provide network power reception equipment with improved reliability without impairing network power reception functions.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of a conventional network power receiving equipment, Fig. 2 is a single line diagram of a network power receiving equipment according to the present invention, Fig. 3 is a block diagram showing the configuration of a network power relay, and Figs. FIG. 5 is a block diagram showing other embodiments of network power receiving equipment with different connection states of loads. 5 _A ~ 5 _C ... Feeder, 11 ... General load, 1
3... Reverse power relay, 7 _A to 7 _C ... Protector disconnector, 90 _A to 90 _C ... Network relay,
M...Regenerative power generation load, TCT...Current combining current transformer, 6 _A to 6 _C ...Network transformer.

Claims (1)

[Claims] 1. A reverse power relay that detects reverse power of a load in a network power receiving circuit and outputs a first reverse power detection signal, and a network relay that detects reverse power from the network bus side. In network power receiving equipment that controls protectors and disconnectors to supply power to loads, the network relay is a reverse power relay that issues a second reverse power detection signal when power is reversely transmitted from the network bus side. a detection circuit;
an overcurrent detection circuit that generates an overcurrent detection signal in the event of an overcurrent; and an overcurrent detection circuit that receives the first and second reverse power detection signals as input and detects the second reverse power when the first reverse power detection signal is not generated. When a detection signal is generated, the protector or disconnector is commanded to be disconnected, and when the first and second reverse power detection signals are generated at the same time, the protector or disconnector is instructed to be disconnected. A first command circuit that commands to prevent the above, and the second reverse power detection signal and the overcurrent detection signal are input, and when both signals are generated simultaneously, the command by the first command circuit is irrelevant. and a second command circuit that issues a command to turn off the protector and the disconnector. 2. The load has a general load and a regenerative power load, each connected to a network bus, and the reverse power relay is provided on a load connection line connecting the regenerative power load. The network power receiving equipment described. 3. The load has a general load and a regenerative power load, and the general load and the regenerative power load are commonly connected to a load-side bus, and the load-side bus and the network bus are connected by a load connection line. The network power receiving equipment according to claim 1, wherein the load connection line is provided with the reverse power relay. 4. The load has a general load and a regenerative power load, and a predetermined number of the general load and the regenerative power load are each connected to the network bus, and each of the load connection lines connecting the respective loads is connected to the network bus. 2. The network power receiving equipment according to claim 1, wherein the reverse power relay is provided via a composite current transformer that combines currents.