CN108390377A - A kind of shore-based power supply system and the method for reducing excitation surge current - Google Patents

Abstract

The present invention discloses a kind of shore-based power supply system and reduces the method for excitation surge current, wherein shore-based power supply system includes the shore electric power device and switchgear of concatenation；Wherein, shore electric power device includes the power conversion unit for connecting AC network, or include power conversion unit for connecting AC network and the output being connect with power conversion unit switch, switchgear includes the output switch for being connected and turning off bank electricity output；It further include the preliminary filling electrical circuit being connect with output switch in parallel；Preliminary filling electrical circuit includes energized circuit for carrying out gentle excitation to the main isolating transformer of shipboard and the field switch whether to work for controlling energized circuit, and energized circuit and field switch are connected in series with.The present invention can reach same purpose by being transformed to existing shore electric power equipment or switch cabinet equipment, without individually increasing the Transformer Close current-limiting apparatus that shoves.

Description

A shore-based power supply system and method for reducing excitation inrush current

technical field

The invention relates to a shore-based power supply system for reducing the excitation inrush current on the ship side, and is especially suitable for the high-voltage boarding application environment in the field of ship shore-based power supply.

Background technique

The structural topology of the existing shore power system is shown in Figure 1, which consists of a shore-based power supply system, a ship-to-shore connection system, and a ship power receiving system.

Among them, a typical shore-based power supply system is generally shown in Figure 2, which includes an input isolation transformer T1, a shore power supply with an output switch Q1, an output isolation transformer T2, and a switch cabinet Q2 connected in series. Among them, T1 is the input isolation transformer (not necessary), which is used to convert the grid voltage to the voltage level required by the shore power supply; if the grid voltage is consistent with the required voltage level, it can be omitted. Q1 is the output switch of the shore power supply itself (not required). T2 is an output isolation transformer (not necessary), used to isolate the output voltage. According to the IEC standard, it generally needs to be added, and it can be omitted only in some occasions with low voltage and low power. The switch cabinet Q2 is the shore power output switch (required), which is used to cut off the final output voltage and current.

A typical ship power receiving system is generally shown in Figure 3, which includes a ship-side main isolation transformer T3, a main switchboard and a distribution switchboard (or lighting, auxiliary switchboard) connected in sequence. Among them, T3 is the main isolation transformer on the ship side, which is necessary for the high-voltage on-board shore power system (not necessary for some low-voltage ships), and is used to match the shore power supply to the voltage level required by the ship.

In use, the transformer must have an excitation process in order to establish a magnetic field from the power-on state to the power-on state. However, if the rated voltage is directly added, an impact excitation current will be generated, which is related to the characteristics of the magnetic circuit and can often reach more than 5 times the rated current. That is to say, the closing excitation inrush current phenomenon exists in the transformer.

Then, in the above-mentioned shore power system, the main isolation transformer T3 on the ship side may have a magnetizing inrush current problem. For the working condition of high-voltage boarding, there must be a main transformer T3 (step-down transformer), the capacity of which is equivalent to the rated capacity of the shore power supply itself. If it is "seamless switching" for power supply - then the transformer T3 on board has been excited, and there will be no excitation inrush current. If it is "slit switching" for power supply - then it is "transformer from unpowered state to powered state". If no measures are taken, the impact current may reach more than 3 times the rated current when the shore side switchgear Q2 is closed.

Aiming at the closing excitation inrush problem of the shore power system, the most common measure is to add a transformer closing inrush current limiting device. As shown in Figure 4, in general, the transformer closing inrush current limiting device is a device connected in parallel with a switch and a resistor, and the excitation current is reduced to a very small level by limiting the current through the resistor (at the same time, the excitation process is also elongated) , thus solving the problem of excessive inrush current.

The above transformer closing inrush current limiting device has the following disadvantages: a separate cabinet needs to be added, which increases the occupied area, and a separate switch is added, resulting in high cost.

Contents of the invention

A brief overview of embodiments of the invention is given below in order to provide a basic understanding of some aspects of the invention. It should be understood that the following summary is not an exhaustive overview of the invention. It is not intended to identify key or critical parts of the invention nor to delineate the scope of the invention. Its purpose is merely to present some concepts in a simplified form as a prelude to the more detailed description that is discussed later.

This application transforms the existing shore power supply equipment or switchgear equipment without separately adding a transformer closing inrush current limiting device to achieve the same purpose.

According to the first aspect of the present application, a shore-based power supply system is provided, which includes a series-connected shore power supply device and a switch cabinet; wherein, the shore power supply device includes a power conversion unit for connecting to an AC grid, or includes The power conversion unit used to connect to the AC power grid and the output switch connected to the power conversion unit, the switch cabinet includes an output switch used to turn on and off the shore power output; The charging circuit; the pre-charging circuit includes an excitation circuit for gently exciting the main isolation transformer on the ship side and an excitation switch for controlling whether the excitation circuit works, and the excitation circuit and the excitation switch are connected in series.

When the shore power supply device includes a power conversion unit for connecting to an AC grid and an output switch connected to the power conversion unit, the pre-charging circuit is connected in parallel with the output switch of the switch cabinet.

When the switch cabinet includes a shore power output switch for shutting off the final output voltage and current, the pre-charging circuit is connected in parallel with the output switch of the shore power supply device.

According to the second aspect of the present application, a method for reducing the inrush current is provided, which is used in a shore-based power supply system, and the shore-based power supply system includes a series-connected shore power supply device and a switch cabinet; wherein, the shore power supply The device includes a power conversion unit for connecting to an AC grid and an output switch connected to the power conversion unit; the method includes:

In the shore power supply device, a pre-charging circuit connected in parallel with the output switch is provided, and the pre-charging circuit includes an excitation circuit for gently exciting the main isolation transformer on the ship side and an excitation switch for controlling whether the excitation circuit works , the excitation circuit and the excitation switch are connected in series;

When supplying power, the excitation switch is closed, and the shore power supply device outputs no-load voltage and gradually increases until the output rated voltage;

Connect the main isolation transformer on the ship side, and gently excite the main isolation transformer on the ship side by the excitation circuit;

After the excitation of the main isolation transformer on the ship side is completed, the output switch is closed and the excitation switch is turned off to supply power to the connected ship side.

According to the third aspect of the present application, a method for reducing the inrush current is provided, which is used in a shore-based power supply system. The shore-based power supply system includes a series-connected shore power supply device and a switch cabinet; wherein, the switch cabinet includes An output switch for turning on and off the shore power output; it is characterized in that: the method includes:

In the switch cabinet, set a pre-charging circuit connected in parallel with the shore power output switch, the pre-charging circuit includes an excitation circuit for gently exciting the main isolation transformer on the ship side and an excitation switch for controlling whether the excitation circuit works , the excitation circuit and the excitation switch are connected in series;

When supplying power, the shore power supply device has no-load output voltage and gradually increases until the output rated voltage;

Connect the main isolation transformer on the ship side, close the excitation switch, and gently excite the main isolation transformer on the ship side by the excitation circuit;

After the excitation of the main isolation transformer on the ship side is completed, close the shore power output switch of the switch cabinet, and disconnect the excitation switch to supply power to the connected ship side.

Wherein, the shore power supply device includes a power conversion unit for connecting to an AC power grid and an output switch connected to the power conversion unit, the pre-charging circuit is connected in parallel with the output switch of the switch cabinet, and when supplying power, first close the The output switch of the shore power supply device, and then make the no-load output voltage of the shore power supply device, and gradually increase until the output rated voltage.

In the above solution, the pre-charging circuit can be in the form of "resistance + mechanical switch", or "resistor + electronic switch", or "electronic switch PWM on", for example, the pre-charging circuit is realized by a series connection of resistors and electronic switches. When the transformer is closed, the electronic switch controls to connect the pre-charging circuit, so that the resistor is connected in series to the circuit. After the preset condition is reached (such as reaching the preset time or reaching the preset voltage and current value), the electronic switch is disconnected, and the resistor is connected to the main circuit. The circuit is disconnected so that the shore-based power supply system can normally supply power to the ship. The principle of the mechanical switch and the electronic switch are the same, and will not be described in detail here. Another example is that the pre-charging circuit is realized by an electronic switch controlled by a PWM signal. When the transformer is switched on, the electronic switch controls the pre-charging circuit to be connected, so that the PWM signal is connected in series to the circuit. After setting the voltage and current value), the electronic switch is disconnected, and the PWM signal is disconnected from the main circuit, so that the shore-based power supply system can normally supply power to the ship. An electronic switch refers to an operating unit that uses electronic circuits and power electronic devices to realize circuit switching, including at least one controllable electronic drive device, such as a thyristor (integrated gate commutated thyristor IGCT), transistor (such as an insulated gate bipolar transistor) IGBT), FET, thyristor, relay, etc.

As an example, the pre-charging circuit includes a series-connected resistor and an excitation contact switch, the resistor is used to gently excite the main isolation transformer on the ship side, and the excitation contact switch is used to control whether the resistor is connected to the circuit to enter the working state. When the transformer is switched on, the excitation contact switch controls the connection of the circuit, so that the resistor is connected in series to the circuit. After the preset condition is reached (for example, the preset time is reached or the preset voltage and current value is reached), the excitation contact switch is disconnected, and the resistor is connected to the circuit. Disconnect from the circuit so that the shore-based power supply system can normally supply power to the ship.

Using the method and device of the present invention, compared with the prior art, the same purpose can be achieved only by modifying the existing equipment, avoiding adding a complete set of transformer closing inrush current limiting device ( Expensive and bulky). By adopting the above solution of the present invention, the effect of reducing the occupied area is achieved, the cost is saved, and the utility model has good practicability.

Description of drawings

Fig. 1 is a topological diagram of the shore power system structure in the prior art;

2 is a schematic diagram of a shore-based power supply system in the prior art;

Fig. 3 is a schematic diagram of a ship power receiving system in the prior art;

FIG. 4 is a schematic diagram of an existing closing inrush current limiting device;

Fig. 5 a is the schematic diagram (with transformer) of the modified shore power supply device in embodiment 1;

Figure 5b is a schematic diagram of the modified shore power supply device in Example 1 (without a transformer);

Fig. 6a is a diagram of a first embodiment of a pre-charging circuit;

Fig. 6b is a second embodiment diagram of the pre-charging circuit;

Fig. 6c is a diagram of a third embodiment of the pre-charging circuit;

FIG. 7 is a schematic diagram of the modified switchgear in Embodiment 2. FIG.

Detailed ways

Embodiments of the present invention are described in detail below, examples of which are shown in the drawings, wherein the same or similar reference numerals designate the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the figures are exemplary only for explaining the present invention and should not be construed as limiting the present invention.

In the description of the present invention, it should be understood that the terms "first", "second", and "third" are used for description purposes only, and should not be understood as indicating or implying relative importance.

In the description of the present invention, it should be noted that unless otherwise specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection. Connected, or integrally connected; it can be mechanically connected or electrically connected; it can be directly connected or indirectly connected through an intermediary, and it can be the internal communication of two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention in specific situations.

The invention provides a shore-based power supply system and a method for reducing the excitation inrush current. The equipment of the existing shore-based power supply system is transformed, and the same purpose can be achieved without separately adding a transformer closing inrush current limiting device; Add a complete set of transformer closing inrush current limiting device.

Example 1

Referring to Figure 5a and Figure 5b, the shore power supply device includes a power conversion unit for connecting to the AC grid and an output switch Q1 connected to the power conversion unit, and also includes a pre-charging circuit connected in parallel with the output switch Q1, the pre-charging circuit includes The excitation circuit used to gently excite the main isolation transformer on the ship’s side and the excitation switch used to control whether the excitation circuit works, the excitation circuit and the excitation switch are connected in series; when the excitation switch is closed, the shore power supply device has no-load output voltage, And gradually increase until the rated voltage is output, then the switchgear is closed, and the excitation circuit gently excites the main isolation transformer on the ship side. After the excitation of the main isolation transformer on the ship side is completed, the output switch Q1 in the shore power supply is closed and disconnected. Excitation switch to supply power to the connected vessel.

In the above solution, the pre-charging circuit includes resistors and excitation contact switches connected in series, the resistors are used to gently excite the main isolation transformer on the ship side, and the excitation contact switches are used to control whether the resistors are connected to the circuit to enter the working state. When the transformer is switched on, the excitation contact switch controls the circuit to be connected, so that the resistance is connected in series to the circuit. After the preset condition is reached (for example, the predetermined time (such as 120ms) or the preset voltage and current value is reached), the excitation contact switch is disconnected. Disconnect the resistor from the circuit so that the shore-based power supply system can supply power to the ship normally.

In addition, in addition to the form of "resistance + mechanical switch" (Figure 6a), the pre-charging circuit can also be in the form of "resistance + electronic switch" (Figure 6b), or the form of "electronic switch PWM on" (Figure 6c), such as the pre-charging circuit It is realized by connecting resistors and electronic switches in series. When the transformer is switched on, the electronic switch controls to connect the pre-charging circuit, so that the resistors are connected in series, and the preset conditions are reached (such as reaching the preset time or reaching the preset voltage and current value) Finally, the electronic switch is disconnected, and the resistor is disconnected from the main circuit, so that the shore-based power supply system can normally supply power to the ship. Among them, the electronic switch in Figure 6b and Figure 6c is a "power thyristor SCR", and there are actually various implementation methods such as IGBT and GTO. The electronic switch in Figure 6b is always on and "buffered" by resistance; while in Figure 6c, it is "buffered" by means of intermittent conduction of the electronic switch.

Another example is that the pre-charging circuit is realized by an electronic switch controlled by a PWM signal. When the transformer is switched on, the electronic switch controls the pre-charging circuit to be connected, so that the PWM signal is connected in series to the circuit. After setting the voltage and current value), the electronic switch is disconnected, and the PWM signal is disconnected from the main circuit, so that the shore-based power supply system can normally supply power to the ship. An electronic switch refers to an operating unit that uses electronic circuits and power electronic devices to realize circuit on-off, and includes at least one controllable electronic drive device. Electronic drive devices include but are not limited to thyristors, IGBTs (Insulated Gate Bipolar Transistors, insulated gate bipolar transistors) ), IGCT (Integrated Gate Commutated Thyristors, integrated gate commutated thyristor), and TCR (Thyristor Controlled Reactor, thyristor controlled reactor), etc. In this embodiment, the pre-charging circuit includes a resistor R1 and a switch cabinet excitation contact switch K1.

In addition, the present invention also proposes a method for reducing the inrush current, which is used in the above-mentioned shore-based power supply system, and the method includes:

Step1: (in Figure 5a or Figure 5b) "shore power supply excitation contact switch K1" is closed;

Step2: (in Figure 2) the shore power supply device starts to output voltage with no load, and gradually increases until the output rated voltage (the shore power supply detects itself);

Step3: (in Figure 2) "Shore power output switch Q2" is closed and connected to the main isolation transformer on the ship side;

Step4: (in Figure 5a or Figure 5b) Gently excite the "main isolation transformer T3 on the ship side" through the "resistor R1" of the shore power supply;

Step5: (in Figure 5a or Figure 5b) After the excitation of the "ship-side main isolation transformer T3" is completed, close the "shore power output switch Q1" in the shore power supply;

Step6: (in Fig. 5a or Fig. 5b) disconnect the "shore power supply excitation contact switch K1" to realize normal power supply for the connected ship side.

Example 2

In this embodiment, different from Embodiment 1, the present invention modifies the switchgear therein, specifically, referring to Fig. 7, the switchgear includes a shore power output switch Q2 for shutting off the final output voltage and current, It also includes a pre-charging circuit connected in parallel with the shore power output switch Q2. The pre-charging circuit includes an excitation circuit for gently exciting the main isolation transformer on the ship side and an excitation switch for controlling whether the excitation circuit works, and the excitation circuit and the excitation switch are connected in series. In this embodiment, the pre-charging circuit includes a resistor R2 and a switch cabinet excitation contact switch K2.

In addition, the structure of the pre-charging circuit in this embodiment is the same as the pre-charging circuit in the first embodiment, and the extension is also the same, and details will not be repeated here.

Based on the above system, the present invention also provides a method for reducing the inrush current, which is used in the shore-based power supply system. The shore-based power supply system includes an input isolation transformer T1, a shore power supply device, an output isolation transformer T2 and a switch connected in series. cabinet; wherein, the switch cabinet includes a shore power output switch Q2 for shutting off the final output voltage and current; the method includes:

Step1: (in Figure 1) "shore power supply output switch Q1" is closed - if there is no Q1, this step is omitted;

step2: (in Figure 1) the shore power supply device starts to output voltage gradually without load, and gradually increases until the rated voltage;

Step3: (in Figure 5a or Figure 5b) connect the main isolation transformer on the ship side, and close the "switch cabinet excitation contact switch K2";

Step4: (in Figure 5a or Figure 5b) through the "resistance R2" of the switchgear to gently excite the "ship side main isolation transformer T3";

Step5: (in Figure 5a or Figure 5b) After the excitation of the "ship-side main isolation transformer T3" is completed, close the "shore power output switch Q2" in the shore power supply;

Step 6: (in Figure 4) disconnect the "switch cabinet excitation contact switch K2" to realize normal power supply for the connected ship side.

By adopting the method and device of the present invention, the existing equipment is used for transformation, without adding a complete set of transformer closing inrush current limiting device, thereby achieving the effect of reducing the occupied area and saving the cost.

Although the present invention has been particularly shown and described in connection with preferred embodiments, it will be understood by those skilled in the art that changes in form and details may be made to the present invention without departing from the spirit and scope of the invention as defined by the appended claims. Making various changes is within the protection scope of the present invention.

Claims (12)

1. a kind of shore-based power supply system comprising the shore electric power device and switchgear of concatenation；Wherein, the shore electric power device Include the power conversion unit for connecting AC network, or include power conversion unit for connecting AC network and The output switch being connect with the power conversion unit, the switchgear include being opened for being connected and turning off the output of bank electricity output It closes；It is characterized in that：It further include the preliminary filling electrical circuit being connect with output switch in parallel；

The preliminary filling electrical circuit includes for carrying out the energized circuit of gentle excitation to the main isolating transformer of shipboard and for controlling The field switch whether energized circuit processed works, energized circuit and field switch are connected in series with.

2. shore-based power supply system according to claim 1, it is characterised in that：The output of the preliminary filling electrical circuit and switchgear Switch in parallel connects.

3. shore-based power supply system according to claim 1, it is characterised in that：The preliminary filling electrical circuit and shore electric power device Output switch in parallel connection.

4. according to any shore-based power supply systems of claim 1-3, it is characterised in that：The preliminary filling electrical circuit includes concatenation Resistance and mechanical switch.

5. according to any shore-based power supply systems of claim 1-3, it is characterised in that：The preliminary filling electrical circuit includes resistance And electronic switch.

6. according to any shore-based power supply systems of claim 1-3, it is characterised in that：The preliminary filling electrical circuit is by PWM The electronic switch of signal control is realized.

7. shore-based power supply system according to claim 5, it is characterised in that：The electronic switch includes at least one controllably Electric drive device, electric drive device is thyristor, transistor, field-effect tube, silicon-controlled or relay.

8. according to claim 1-3 it is any the shore-based power supply system, it is characterised in that：The system further includes being connected to bank electricity The input isolating transformer of supply unit input terminal.

9. according to claim 1-3 it is any the shore-based power supply system, it is characterised in that：The system further includes being connected to bank electricity The output isolation transformer of supply unit output end.

10. a kind of method reducing excitation surge current, in shore-based power supply system, shore-based power supply system to include the bank electricity electricity of concatenation Source device and switchgear；Wherein, the shore electric power device include power conversion unit for connecting AC network and with The output switch of power conversion unit connection；It is characterized in that：This method includes：

In shore electric power device, a preliminary filling electrical circuit being connect with output switch in parallel is set, the preliminary filling electrical circuit includes It energized circuit for carrying out gentle excitation to the main isolating transformer of shipboard and is encouraged for control whether energized circuit work Magnetic switch, energized circuit and field switch are connected in series with；

When power supply, field switch is closed, and shore electric power device idle voltage output simultaneously incrementally increases, until output rated voltage；

The main isolating transformer of shipboard is connected, gentle excitation is carried out to the main isolating transformer of shipboard by energized circuit；

After the completion of the main isolating transformer excitation of shipboard, it is closed output switch, and disconnect field switch, is supplied for the shipboard of connection Electricity.

11. a kind of method reducing excitation surge current, in shore-based power supply system, shore-based power supply system to include the bank electricity electricity of concatenation Source device and switchgear；Wherein, the switchgear includes the output switch for being connected and turning off bank electricity output；Its feature exists In：This method includes：

In switchgear, the preliminary filling electrical circuit that setting one is connect with bank electricity output switch in parallel, the preliminary filling electrical circuit includes using In the excitation for carrying out the energized circuit of gentle excitation to the main isolating transformer of shipboard and whether working for controlling energized circuit Switch, energized circuit and field switch are connected in series with；

When power supply, shore electric power device idle voltage output simultaneously incrementally increases, until output rated voltage；

The main isolating transformer of shipboard is connected, field switch is closed, is gently encouraged to the main isolating transformer of shipboard by energized circuit Magnetic；

After the completion of the main isolating transformer excitation of shipboard, the bank electricity output switch of closure switch cabinet, and field switch is disconnected, for connection Shipboard be powered.

12. the method according to claim 11 for reducing excitation surge current, it is characterised in that：The shore electric power device includes Power conversion unit for connecting AC network and the output switch being connect with the power conversion unit, it is described to be pre-charged back The output switch in parallel of road and switchgear connects, and when power supply, is first closed the output switch of the shore electric power device, then make bank electricity Supply unit idle voltage output simultaneously incrementally increases, until output rated voltage.