JPS62166735A - Private power source changer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an in-station power supply switching device for a liquefied gas fuel base that automatically switches the power supply in a short time and supplies fuel safely and stably. .

[Conventional technology]

In recent years, the demand for electricity has continued to increase.

Along with this, the capacity of each power generation unit has also increased.

Reflecting the global energy situation, the fuels used are diversifying from conventional petroleum to liquefied natural gas (LNG), liquefied propane gas (LPG), coal, or 00M (coal/oil mixed fuel). It's coming. Along with this, large-scale receiving terminals for fuel for these power generation units have also been constructed. Of these, LNG, LPG
At liquefied gas fuel bases such as
Fuel such as PG is vaporized at the receiving base and directly supplied to the power generation plant. For this reason, if a 1-rubble occurs on the receiving base side, it may lead to the suspension of power generation plan 1~, and particularly high reliability is required in the operation of the base.

For this reason, the on-site power supply configuration of liquefied gas fuel bases generally adopts a two-system power receiving type consisting of two systems as shown in Figure 3, and if a failure occurs in one system or there is no warning. Even in the event of a power outage, the power supply can be switched automatically and quickly by simply disconnecting the faulty power supply and turning on the busbar connection breaker. Methods for automatically and quickly switching power supplies include the instant switching method, which shuts off the faulty system when a fault occurs in the system, and switches the system to another healthy power source within a short period of time; A phase detection switching method that switches to another healthy power supply when the phase difference of the residual voltage on the faulty side is within a certain tolerance range (for example, within a phase difference of 20 degrees), and the residual voltage on the faulty side is a specified value, for example 30%. A low voltage switching method that detects with a low voltage detection relay and switches to the healthy power supply, or an optimal time until the residual voltage on the faulty side reaches a specified value, e.g. 30% or less of the rated voltage value. A timed power outage switching method is used in which the power is measured in advance, a timed relay is used to wait for that amount of time plus a margin time, and then the power is switched to the healthy power source.

On the other hand, in the case of a liquefied gas fuel base, there are many auxiliary machines with a small moment of inertia GD2, such as pump loads, so if a failure occurs in the power receiving system, changes in the residual voltage of the bus bar and changes in phase will be less than the conventional Compared to thermal power plants, etc., they have the characteristic of changing at a much faster rate. Therefore, in order to safely switch to a healthy power source without damaging the pump, motor, etc., it has been found that the instantaneous switching method and the phase detection switching method using phase confirmation are impossible.

In addition, the timed power outage switching method requires longer power outages than the low voltage switching method, and the residual voltage characteristics vary significantly depending on the load configuration and the nature of the system accident (failure), so it is not always possible to obtain effective results. Since it is not always possible to obtain the following, it is not likely to be adopted. Therefore, it is no exaggeration to say that in the case of liquefied gas fuel bases, switching to a healthy power source using a low voltage switching method is the mainstream.

[Problem that the invention seeks to solve]

However, in the case of liquefied gas fuel bases, etc., as mentioned above, the fuel is vaporized at the receiving base and directly supplied to the power generation plant, etc., so it is necessary to quickly restore power in the event of a failure. is required. Needless to say, if the power supply is not restored promptly, the seawater pump for the carburetor will stop, and the fuel will not be able to be vaporized, resulting in a trip to the fuel station and, ultimately, the supply of vaporized fuel. This can even lead to a serious accident in which the power generation plant affected by the damage is tripped. Although it is said that the low voltage switching method is the mainstream power supply switching method in the case of liquefied gas fuel bases.

This low voltage switching method also has problems. In other words, as mentioned above, in the case of a fault in the power grid, the low voltage switching method uses a low voltage detection relay to detect that the residual voltage on the faulty side has fallen below a specified value, for example 30%, and switches the power supply bus on the healthy side. The system attempts to restore power by turning on the connecting breaker connected to the bus, but when the bus line connecting breaker is turned on, the auxiliary motors connected to the faulty bus are connected to IP and Ll.

Voltages will be applied before and after the bus, and a large inrush flow will flow into the system components such as the transformer of the healthy power supply connected to the busbar connection breaker and the station busbar, and in some cases, liquefied gas will flow. It may even lead to system 1-rip at the fuel station. Therefore, in the case of a liquefied gas fuel base, the minimum number of auxiliary equipment necessary to continue operating the system, such as the electric motor for the vaporizer seawater pump, is forcibly disconnected from the bus line at the same time as the accident system is disconnected. It is necessary to prevent excessive inrush current from flowing to the system components on the healthy side.

On the other hand, power to the seawater pumps for fuel vaporization at the liquefied gas fuel base needed to be restored as soon as possible, that is, before the rotational speed dropped and the flow rate stopped, so power was lost due to the accident. Immediately after this is detected by the low voltage detection relay, other auxiliary equipment must be configured to selectively cut off the load.

In view of the above-mentioned problems, the present invention promptly removes the faulty system without affecting the healthy power supply even in the event of a power system failure, and automatically and quickly switches the R and M sources to the healthy power supply. Our objective is to provide an on-site power switching device that allows stable and safe operation of a liquefied gas fuel base.

[Means for solving problems]

Power is received through a common bus, and this power supply is divided into two systems within the plant. When one system's power supply fails, the load of the failed system is selectively cut off, and the power is disconnected from the healthy system's bus by disconnecting the bus line breaker. In an in-station power supply switching device configured to receive power supply, a fault signal of the faulty system is added as a condition for selective load cutoff, and the faulty system is forcibly cut off and the faulty system is disconnected, automatically and in a short time. The feature is that the busbar is switched to a healthy system power supply.

[Effect]

Therefore, in the present invention, selective load shedding is not performed only by the operation of the low voltage detection relay, but only by adding a failure signal for the faulty system as a condition for one selective load shedding, and selective load shedding is forcibly performed for the healthy system. The system is designed to quickly disconnect the faulty system without affecting the power supply as much as possible, automatically switch the power supply to a healthy power supply in a short time, and create a configuration that allows the liquefied gas fuel base to continue operating stably and safely. An embodiment of the present invention will be described using FIGS. 1 and 2. FIG. 1 is a control block diagram showing one embodiment of the present invention, and FIG. 2 is a diagram illustrating the time course when a failure occurs in the control block diagram of FIG. 1 and power supply switching is actually performed. This explains the voltage behavior and operating characteristics of various component devices.

The symbols used in the figures are the same as those used in the above description. However, 86ZA is a failure signal of A system,
862B is a failure symbol of the B system and constitutes one component of the present invention.

The configuration c'= of these conventional techniques will be explained using FIGS. 3, 4, and 5. Figure 3 is a diagram of the on-site power supply configuration of the liquefied gas fuel base, where 1 is the power supply, 2 is the common bus, and 3 is the A
System bus 4 is a B system bus. 52BT is connected to each power receiving breaker 52A in the event of an accident in A system or B system.
This is a busbar connection breaker that opens L or 52BL and allows it to receive power from the healthy side. 11 is the common bus breaker for the A system, 12 is the lifting transformer for the A system, and 21 is the B
The common bus breaker for the system, 22, is a lifting transformer for the B system. I4 and 24 are the loads of the gas fuel station, 1
4 is the load of the A system, and 24 is the load of the B system. 13 and 23
is a load breaker for starting and stopping these loads, and the loads 14 and 24 are connected to the bus 3 of the A system and B system, respectively, via the load breakers 13 and 23.
or connected to 4. 15 and 25 are busbars 3 and 4
It is a transformer for transforming the voltage of 27A and 27A.
B is a low voltage detection relay for the A system and B system buses 3 and 4. Figure 4 shows, for example, a busbar connection breaker 52nT in the event of an accident on the upstream side of the transformer 12 of system A.
and conditions for selective load cutoff associated with bus bar switching are explained using a block diagram. Further, FIG. 5 explains the voltage behavior over time and the operation characteristics of various component devices in the above block diagram when bus bar switching is actually performed.

As shown in Figure 3, a power source 1 is received through a common bus 2, and within the station, this power source is divided into two systems, A system and B system, to constitute the power source of the liquefied gas fuel base, and to ensure stable operation of the base. A case in which a power supply failure such as a 31G (three-wire ground fault) accident occurs at the A-system transformer 12 or its upstream side while the system is in use will be described in detail. When a failure like 31G occurs in the transformer 12 of the A system or its upstream side, as shown in Figure 5, the station bus voltages 3 and 4 of the A system and B system drop to zero at the same time as the failure occurs (to). , until the common bus breaker 11 of the A system is "opened" (up to 11) is the failure duration time, and the station bus voltage remains zero and does not recover. on the other hand,
When the common bus breaker 11 is "opened" and the fault is cleared, the bus voltage 4 of the B system, which is a healthy system, returns to the value before the fault. However, the faulty system A recovers to a certain value due to the residual voltage of the load, but since the common bus breaker 11 is "opened" and the power supply is lost, the residual voltage of the load increases as the load rotates. It will attenuate as the number changes. In addition, the A system has a low voltage detection relay 27.
Along with the operation of A, as shown in Figure 4, the self-system A
The load circuit breaker 13 of the system is selectively disconnected, and the AND condition with the "open" condition of the common bus circuit breaker 11 is established via the confirmation timer 'F to ensure that the voltage does not recover, and the bus connection is established. Shutdown 'd'J 52 [IT will cut off the power supply from the healthy B system.

That is, the load is selectively cut off by the operation of the low voltage detection relay 27A, and the bus line communication breaker 52BT is "closed" via the operation plus confirmation timer of the common bus breaker 11 and the low voltage detection relay 27Δ to ensure a healthy state. It receives power from the B, \- system, which is the system.

Selective load disconnection is performed, and the busbar connection breaker 52BT
When it is "closed", the voltage of the bus 3 of the failed system A also returns to the value before the failure. In addition, from FIGS. 4 and 5 and the explanation, the power reception breaker 52 of the fault system (A, V-system)
Although AL is not explained, it is omitted because in this type of system and accident, the power reception breaker 52AL is also opened at the same time as the common bus breaker 11 is opened.

However, the failure occurs at t. As shown in Figure 5, in the current system, even if the system is healthy, the 'm pressure becomes zero until the fault is cleared (time 11), and the system is connected to the B system bus. low voltage detection relay 2
711 operates, and even the loads connected to the healthy bus 4 are immediately and selectively cut off. In the case of a liquefied gas fuel base, most of the load will be disconnected, paralyzing the base's functions, causing the base to trip, and causing vaporized gas to be removed from the base. There is a risk that even the power plants that receive the supply will trip.

As described above, a failure occurs in the A-system transformer 12 or its upstream side, and the failure continues until the common bus breaker 11 is "opened". However, when the common bus breaker 11 is opened, the healthy system B returns to its original state. However, even if the common bus breaker 11 is opened and the power reception breaker 52AL is opened, the voltage on the bus 3 does not recover to the original voltage until the bus breaker 52 completes its operation. On the other hand, when switching busbars, as explained in the conventional technology section, if the full load is connected, a large inrush current will flow in the healthy system, which will not only damage the equipment but also cause Plan 1 to trip. It is necessary to select as many loads as possible and perform selective load shedding at the same time as disconnecting the faulty system. Therefore, in the present invention, a fault signal of a fault system is added as a condition for one selection load cutoff.

That is, the occurrence of a failure t. In this case, the low voltage detection relays 27A and 27B of the A system and the B system both operate, but when the faulty system is cleared (disconnected), the low voltage detection relay 2711 in the B system, which is a healthy system, is automatically activated. Returns to the original inactive state. Therefore, a fault signal 86ZA is configured based on the condition that the fault signal of the transformer 12 or the common bus breaker 11 is "open", and this fault signal 86Z
Under the condition that A and low voltage detection relay 27A are operating, the faulty load is selectively and forcibly disconnected from the grid.

When the timer '1' has elapsed for a predetermined waiting time, the common bus breaker 11 is "open" and the bus line breaker 52BT is in a "closed" operation.

On the other hand, in system B, which is a healthy system, the low voltage detection relay 27B operates once, but the fault is cleared and returns to the original non-operating region at 3 o'clock, and the fault signal of the transformer 22 or f3 > f : common bus breaker 21 of a
The failure signal 862A cannot be generated unless the condition that the 4-channel is "open" is met. Therefore, even if the low voltage detection relay operates, the load breaker 23 for selective load cutting off in the healthy system of the B system will not be "opened", and even though it is only one system of the B system, the load breaker 23 is not opened. maintain the operation of
It is possible to continue. In the description of the prior art and the embodiment of the invention, a failure on the A system side has been described, but the same applies to a transformer failure in another B system, which is divided into two systems, and it goes without saying that the same effect can be expected.

Furthermore, a similar effect can be expected by using a signal indicating that the power receiving breaker of the system is "open" as one of the fault signals in place of the transformer fault signal or the condition of "common bus breaker open."

〔Effect of the invention〕

As explained above, according to the present invention, even if a serious accident such as a 3LG (3-wire ground fault) occurs in one line of a duplicated AC power supply, it will not affect the healthy system power supply as much as possible. This makes it possible to automatically and quickly switch from a faulty system to a healthy power supply.

Serious events such as plant trips at liquefied gas fuel bases
It is possible to provide an in-station power supply switching device that can prevent accidents from occurring.

[Brief explanation of drawings]

1 and 2 are block diagrams showing one embodiment of the present invention, and a time chart 1-1 for explaining the same. FIG. 3 is a diagram showing the structure of the in-house power source of a liquefied gas fuel base, and FIG. and FIG. 5 is a block diagram showing a conventional low voltage power supply switching system and a time chart for explaining the same. 1...Power supply, 2...Common bus, 3.4...A
, B system bus, 11.12・A, B system common bus breaker, 12.22
・・A, B system transformer, 52 BT・・Bus bar connection breaker, 13.23・・Load breaker, 14.24・・Load. 27A, 27[3...A, B system low voltage detection relay. 86ZA...A system failure signal, 86ZB...B system failure signal, T...Timer representative Patent attorney Nori Chika Ken Yudo Hirofumi MitsumataFigure 1Figure 3Figure 4Figure 2Figure 5

Claims (1)

[Claims] Power is received through a common bus, and this power supply is divided into two systems within the plant. When one system's power supply fails, the faulty load is selectively cut off, and the power is disconnected from the healthy bus via a busbar connection breaker. In the station power switching device configured to receive power supply, a fault signal of the faulty system is added as a condition for selective load cutoff, and the faulty system is forcibly cut off and the faulty system is disconnected, automatically and in a short time. An in-station power supply switching device characterized by switching the busbar to a healthy system power supply.