CN104979894A - RMU uninterrupted power supply load transfer method - Google Patents

Abstract

The invention discloses a load transfer method for a ring network cabinet without power failure. The method includes the following steps: 1) Using the secondary side wiring hole outside the ring network cabinet as a control switch corresponding to the incoming line and a normally open contact switch in the ring network cabinet The nuclear phase hole for determining the phase sequence; 2) Perform two-two nuclear phase for each phase nuclear hole corresponding to the incoming line control switch and each phase nuclear phase hole corresponding to the normally open contact switch; 3) For the corresponding The check phase hole of the incoming line control switch and the check phase hole corresponding to the normally open connection switch are checked for the same power source; The secondary wiring of the switch is correct, and the phase sequence of the lines on both sides of the normally open contact switch is correct. At this time, close the normally open contact switch, and then disconnect the power station switch on the corresponding side, so as to realize the non-stop power supply (ring closure) of the interconnection line of the ring main unit. transfer load. The invention is easy to implement, simple and safe to operate, and greatly improves the power supply reliability of the urban distribution network.

Description

Ring network cabinet load transfer method without power failure

technical field

The invention belongs to the field of automatic operation of power grids, and in particular relates to a load transfer method of a ring network cabinet without power failure.

Background technique

The power distribution ring network refers to two or more power distribution lines that form a "hand in hand" line. Control switches are set for each line in sections, and contact switches are set at the connection points of the lines to realize the interconnection of branch and trunk lines. When the line If a certain part of the system fails, the faulty part can be isolated in time, and the power supply can be normally supplied to the load from the switches on both sides, so as to reduce the loss of power failure. With the rapid development of social economy, the urban distribution network structure has changed greatly, and cable lines have gradually replaced overhead lines and occupied a major position. The existing urban power distribution ring network generally adopts ring network cabinets for interconnection, as shown in Figure 1 and Figure 2.

The ring network cabinet refers to a set of high-voltage switchgear installed in a metal or non-metal insulated cabinet or made into an assembled compartment type electrical equipment. The ring network cabinet is equipped with a busbar and its incoming and outgoing line equipment to complete receiving and distributing power. , Combined load current, overload current and short circuit current. The high-voltage busbar and the interval between the incoming and outgoing lines inside the ring network cabinet are closed by the front baffle, and the front baffle and the grounding knife switch form an interlock. Remove the board to ensure the personal safety of on-site operation and maintenance.

In the power distribution ring network, the non-stop power supply (ring closing) transfer load refers to the operation of first closing the ring network line, transformer or circuit breaker string to form a network in the electrical operation, and then disconnecting the operation of the power station switch on the corresponding side, so as to Take Figure 1 or Figure 2 as an example, that is, close the normally open contact switch first, then turn off the switch of power station 1 (or power station 2), and transfer the power load of the line from power station 1 (power station 2) to power station 2 (power station 1) )powered by. According to the operating characteristics of the three-phase AC power system, when the power system is in normal operation, the distribution line must be checked and correspondingly correct on both sides of the contact switch before the loop can be closed, that is, the load is transferred without power failure. If the phase sequence of the lines on both sides of the contact switch is not correct, and the contact switch is closed rashly, it will cause a short circuit of the line and cause serious accidents such as equipment burnout. However, due to the "fully insulated and fully sealed" structure adopted by the ring network cabinet, its high-voltage live body is encapsulated in the cabinet, and it is impossible to directly check the phase sequence of the lines on both sides of the contact switch during normal live operation. Mode adjustment, that is, power outage and power transfer to load. As a result, it will have a serious impact on high-quality electric power services, lean management of power supply enterprises, and on-site electric power operation safety.

In order to cope with this problem, some local power supply enterprises have developed the technology of load transfer of ring main unit without power failure based on "bypass live operation". The so-called bypass transfer technology refers to the use of bypass cable cars, bypass distribution vehicles and other equipment to build cable bypass on the normal power supply line and transfer the power supply load, and the bypass cable (equipment) temporarily replaces the normal power supply. Line (device) powered. However, the implementation and coordination of this technology is difficult, and the requirements for comprehensive collaboration capabilities are very high. Every time before implementing this technical operation, it is necessary to dispatch large-scale emergency bypass cable cars, live work vehicles and other electric construction vehicles. The live equipment around the operation point needs to be surrounded by a protective net. The implementation site requires the cooperation of about 30 staff, which consumes a lot of money. More time and energy.

Contents of the invention

The purpose of the present invention is to provide a method for transferring loads without power failure of the ring main unit which is easy to implement, simple to operate, safe and reliable.

The load transfer method of the ring main unit without power failure provided by the present invention comprises the following steps:

1) Determine the ring main unit to be closed. At this time, the normally open contact switch in the ring main unit is in the disconnected state;

2) The secondary side wiring hole outside the ring network cabinet is used as the nuclear phase hole for measuring the phase sequence corresponding to the incoming line control switch and the normally open contact switch in the ring network cabinet;

3) Carry out two-two phase checks for each phase check hole corresponding to the incoming line control switch, and perform two-two checks for each phase check phase hole corresponding to the normally open contact switch, and determine the incoming line control switch and the normally open contact switch Whether the secondary wiring is wrong and connected.

4) Carry out the same power supply verification for the nuclear phase hole corresponding to the incoming line control switch and the nuclear phase hole corresponding to the normally open contact switch: one side of the normally open contact switch is connected to the busbar, and the other side is connected to the contact cable. For the contact cable The other end of the connection is also connected with a normally closed contact switch, disconnect the normally closed contact switch, then close the normally open contact switch, and connect the nuclear phase hole corresponding to the incoming line control switch and the nuclear phase hole corresponding to the normally open contact switch. Carry out one-by-one phase verification among the corresponding phases, and judge whether the corresponding voltages of the incoming line control switch and the secondary wiring of the normally open contact switch are in the same phase.

5) Perform different power supply verification on the nuclear phase hole corresponding to the incoming line control switch and the nuclear phase hole corresponding to the normally open contact switch: pull the closed normally open contact switch to make it in the disconnected state, and The normally closed contact switch that has been disconnected is closed, and the phase verification hole corresponding to the incoming line control switch and the phase verification hole corresponding to the normally open contact switch are mutually checked one by one among the corresponding phases, and the incoming line control is judged again. Whether the voltage corresponding to the secondary wiring of the switch and the normally open contact switch is in the same phase.

6) After steps 3 to 5 are all judged correctly, it is determined that the secondary wiring between the incoming line control switch and the normally open contact switch is correct, and the phase sequence of the lines on both sides of the normally open contact switch is correct. At this time, close the normally open contact The switch realizes the ring-closing operation of the contact line of the ring network cabinet, and then disconnects the switch of the power supply station to be stopped, so as to transfer the power load of one side of the distribution line to the other side through the contact switch of the ring network cabinet without power failure (ring closure) Line powered.

The nuclear phase is judged by the AC voltage waveform.

The nuclear phase is measured by an instrument for measuring the AC voltage phase difference.

The method of load transfer without power failure of the ring network cabinet of the present invention is to realize the load transfer without power failure by first checking the phase of the contact lines on both sides of the ring network cabinet and then performing the ring closing operation. Compared with the prior art, the present invention does not need to add any equipment, nor does it require any capital investment, and the operation is simple, safe and reliable, the workload is small, and the technical difficulty is low. It is necessary to cut off the power supply of the load to be transferred, and realize the load transfer smoothly without affecting the normal operation of the load to be transferred. The invention greatly improves the power supply reliability of the urban distribution network, improves the high-quality power service level, simplifies the operation and maintenance operation process and the amount of personnel operations, and effectively avoids the loss of load.

Description of drawings

Fig. 1 is a schematic diagram of a power distribution ring network in the prior art.

Fig. 2 is a schematic diagram of a distribution line tie switch in the prior art.

Fig. 3 is a schematic diagram of a distribution line tie switch according to a specific embodiment of the present invention.

Fig. 4 is a schematic diagram of two core phases in the same compartment of the ring main unit of the present invention.

Fig. 5 is a schematic diagram of the ring main unit and the power core of the present invention.

Fig. 6 is a schematic diagram of different power sources and nuclear phases of the ring main unit of the present invention.

Detailed ways

As shown in Figure 3, it is a schematic diagram of a distribution line tie switch of a specific embodiment of the present invention. In order to make the image more clearly displayed, this schematic diagram only draws a single phase, and the three-phase diagram is the same as the one-way diagram. This implementation mode is an example where power is supplied by two power stations A and B. There are two ring network cabinets of A and B correspondingly between the distribution line of Power Station A and the distribution line of Power Station B. Each ring network cabinet has an incoming line control Switches (401 and 404), a contact switch (402 and 403), wherein the contact switch in the ring network cabinet is a normally open contact switch, the contact switch in the ring network cabinet is a normally closed contact switch, and the contact switch in the ring network cabinet is a normally closed contact switch. The normally open contact switch in the network cabinet is connected with the normally closed contact switch in the second ring network cabinet through a contact cable. Each ring network cabinet has its own secondary wiring hole outside, and the secondary wiring hole has obtained the low voltage corresponding to the primary wiring coupling. Taking advantage of this, the present invention uses the secondary side wiring hole as the corresponding The check-phase holes of the incoming line control switch and the normally open tie switch are used to measure the phase sequence, and the phase sequence of the lines on both sides of the normally open tie switch is checked. When the check phase confirms that the phase sequence is consistent, the ring can be closed. Such as substation B needs power outage maintenance, the load originally powered by substation B must be transferred to substation A to supply power, and the method of the present invention is used to transfer the load of substation B without power outage, and it is necessary to connect the normally open contact switch (402) in the ring network cabinet twice The phase of the side line is checked, and the phase sequence can be closed only after the phase sequence is completely correct, and then the load is transferred without power failure. The specific method is as follows:

Step 1: Two core phases in the same compartment of a ring network cabinet, see Figure 4, details are as follows:

Keep the incoming line control switch 401 closed and the normally open contact switch 402 disconnected, and obtain a low voltage value (30~100V) in the secondary wiring hole arranged in the ring network cabinet. The waveform and amplitude of the high and low voltage are proportional to each other. Keep the frequency consistent, use the instrument for measuring the phase difference of AC voltage, and perform a phase verification on the secondary wiring hole A of the same line, the secondary wiring hole B of the same line, and the secondary wiring hole C of the same line. 401 is: 401A pair 401B, 401A to 401C, and 402 are: 402A to 402B, 402A to 402C; because "the three-phase AC power system A/B/C three-phase voltage phase difference is 120° in turn, if there is no parallel connection or If the wiring is wrong, the phase difference between the two nuclear phases must be 120° and 240°; if there is a parallel connection or wiring error in the secondary wiring at this interval, the phase difference between the two nuclear phases must be 0° and 0° ° or 0° and 120° or 0° and 240° or 120° and 120° or 240° and 240°, so through this step, the pairwise core phase results of the lines at the same interval are measured, and the incoming line control switch 401 and normal Whether there is a parallel connection error in the secondary wiring corresponding to the interval of opening the contact switch 402. The details are shown in the following table:

Table 1

Step 2: The A ring network cabinet first has the same power core phase, and then different power core phases, as shown in Figure 5 and Figure 6:

It can be seen that two different intervals are connected to the phase busbars in the A ring network cabinet; the phase busbars are also divided into A phase, B phase and C phase; the left interval in Figure 5 and Figure 6 is powered by A substation, and the power supply line One phase of the power supply line is connected to a certain phase of the phase busbar, and the right interval is powered by substation B, and one phase of the power supply line is also connected to a certain phase of the phase busbar; the following method can be used to determine the secondary Whether the wiring and the phase sequence on both sides of the contact switch are correct:

①Same as power supply nuclear phase: First disconnect the normally closed contact switch 403 connected with the contact cable, and then close the normally open contact switch 402 connected with the contact cable. At this time, the distribution circuit is shown in Figure 5, and the contact switch 402 is connected at this time Both sides of the line are powered by the same power supply (substation A); on this basis, use the instrument for measuring the phase difference of AC voltage to connect the corresponding secondary nuclear phase holes of the switches 401 and 402 to the ring network cabinet between the corresponding phases Measure one by one, that is, 401A to 402A, 401B to 402B, 401C to 402C. If the phase difference shows that they are all in phase, continue to the next step. If the phase difference shows that any pair is out of phase, then determine that the ring network cabinet 401 , The 402 switch corresponds to the secondary wiring error, and the secondary wiring must be reconnected until the above phase difference is met;

② Different power source nuclear phase: On the basis of ①, restore the normally open contact switch 402 to the disconnected state, and then close the normally closed contact switch 403, as shown in Figure 6. At this time, the two sides of the contact switch 402 are connected by different routes. Power supply; on this basis, use the instrument for measuring the phase difference of AC voltage to measure the corresponding phases of the secondary nuclear phase holes corresponding to the switches 401 and 402 connected to the ring network cabinet, that is, 401A to 402A, 401B For 402B, 401C, and 402C, judge the secondary connection and phase sequence of the lines on both sides of the ring network cabinet according to the phase difference. If the phase difference shows that they are all in the same phase, continue to the next step. If the phase difference shows that any If it is out of phase, it is determined that the phase sequence of the distribution lines on both sides of the contact switch of the ring main unit is wrong, and the phase sequence of the distribution lines on both sides must be commutated until it is correct.

Combining the judgment results of the above step 1: two core phases separated by the same phase, and step 2: first the same power core phase and then different power core phases, it can be correctly judged whether the secondary side wiring in the A ring network cabinet is correct, and whether the two sides of the normally open contact switch are correct. Whether the phase sequence of the line is correct. Once the secondary wiring and phase verification are correct, it is determined that the phase sequence of the lines on both sides of the normally open contact switch 402 is correct. This verification method effectively prevents the so-called "reverse connection of the primary side, The secondary side is also reversed, and the same power supply core is used to verify the occurrence of the situation of "negative negative becomes positive". At the same time, when performing phase verification, an instrument for measuring the phase angle difference must be used to check the corresponding phase angle difference of the three-phase AC voltage, instead of an instrument for measuring the difference of the three-phase AC voltage, that is, the "phase difference of the same phase voltage is zero". , out-of-phase voltage difference of 100V" to judge, because the voltage coupled to the secondary wiring hole of the ring network cabinet is not a standard value, due to the deviation of the coupling voltage and the secondary wiring resistance, according to the actual measurement of the ring network cabinet in the system, the ring network cabinet two The voltage coupled to the secondary wiring hole ranges from 30 to 100V, and it is impossible to draw the conclusion that "the voltage difference between the same phase is zero and the voltage difference between different phases is 100V" for the secondary wiring hole.

Step 3: The non-stop power-off (ring closing) operation of the interconnection line of the ring main unit is transferred to the power load, as shown in Figure 6:

① On the basis of steps 1 and 2, close the normally open contact switch 402 of the ring main unit A to close the distribution line of power station A and power station B;

② Turn on the corresponding switch of power station B to realize the power transfer of the distribution line load of station B to the distribution line of station A without interruption.

Claims (3)

1. ring main unit does not have a power failure a load transfer method, comprises the steps:

1) determine the ring main unit of pending Loop Closing Operation, the interconnection switch of often opening now in ring main unit is in off-state;

2) outer for ring main unit secondary side wiring hole is used for corresponding to inlet wire control switch and Chang Kai interconnection switch in ring main unit the nuclear phase hole measuring phase sequence;

3) nuclear phase is between two carried out to each phase nuclear phase hole corresponding to inlet wire control switch, carry out nuclear phase between two to corresponding to each phase nuclear phase hole of often driving interconnection switch, judge inlet wire control switch and often open interconnection switch secondary connection whether wrong and connect;

4) to the nuclear phase hole corresponding to inlet wire control switch and carry out same power supply nuclear phase corresponding to the nuclear phase hole of often driving interconnection switch: often open interconnection switch one side joint busbar, another side joint link cable, the other end for link cable is also connected with one and often closes interconnection switch, disconnect this and often close interconnection switch, then close and describedly often drive interconnection switch, to corresponding to inlet wire control switch nuclear phase hole and corresponding to often open interconnection switch nuclear phase hole each corresponding mutually between carry out mutually nuclear phase one by one, judge inlet wire control switch and often open interconnection switch secondary connection corresponding voltage whether same-phase;

5) to the nuclear phase hole corresponding to inlet wire control switch and carry out different power supply nuclear phase corresponding to the nuclear phase hole of often driving interconnection switch: operate a switch to the interconnection switch of often opening closed, make it to be in off-state, combined floodgate is performed to the normal conjunction interconnection switch disconnected, to corresponding to inlet wire control switch nuclear phase hole and corresponding to often open interconnection switch nuclear phase hole each corresponding mutually between carry out mutually nuclear phase one by one, again judge inlet wire control switch and often open interconnection switch secondary connection corresponding voltage whether same-phase;

6) after passing through the equal correct judgment in step 3 ~ 5, correctly, often to open the phase sequence of interconnection switch both sides circuit corresponding correctly with often opening the secondary connection of interconnection switch to assert inlet wire control switch, now close and often drive interconnection switch, realize the Loop Closing Operation of ring main unit both sides distribution line, disconnect the switch in power station to be stopped power supply again, realize side distribution line electric load to turn and be fed to opposite side distribution line by the cyclization that do not have a power failure of ring main unit interconnection switch and power.

2. a kind of ring main unit according to claim 1 does not have a power failure load transfer method, it is characterized in that described nuclear phase judges with alternating voltage waveform.

3. a kind of ring main unit load transfer method according to claim 1 and 2, is characterized in that described nuclear phase adopts the instrument measuring alternating voltage phase difference to carry out measurement nuclear phase.