CN110249494B

CN110249494B - Power distribution system for mobile body

Info

Publication number: CN110249494B
Application number: CN201880009197.1A
Authority: CN
Inventors: 后藤良介; 江崎秀明; 德山和马; 小野寺达也; 原田芳辉; 久次米泰典; 大野达也
Original assignee: Kawasaki Jukogyo KK
Current assignee: Kawasaki Motors Ltd
Priority date: 2017-01-31
Filing date: 2018-01-23
Publication date: 2022-11-18
Anticipated expiration: 2038-01-23
Also published as: TWI661635B; CN110249494A; TW201841449A; JP6838979B2; WO2018143013A1; JP2018125941A

Abstract

A power distribution system for a mobile body includes: a 1 st power system connected to a generator and a 1 st power load in which a variation amount of power is smaller than a predetermined value; a 2 nd power system connected to a 2 nd power load whose fluctuation amount can be equal to or greater than a predetermined value; a 1 st power converter; a 2 nd power converter; a 3 rd power converter and a bus breaker. The bus breaker is in a connected state when the 2 nd power load is not operated and is in a disconnected state when the 2 nd power load is operated, and controls the 1 st power converter based on a 1 st power command value provided by a low frequency component smaller than a predetermined frequency out of actual power values of the 2 nd power converter, thereby performing droop control on the 2 nd power converter. The 3 rd power converter is controlled in power to eliminate imbalance of power flowing into and out of the dc intermediate section.

Description

Power distribution system for mobile body

Technical Field

The present invention relates to a power distribution system for a mobile body.

Background

Conventionally, a propulsion system for a moving body such as a ship is known (see patent document 1). Recently, from the viewpoint of improvement in efficiency and reduction in maintenance cost obtained by using a generator with a high load, a technique of operating electric power of a mobile body using only 1 generator (hereinafter, also referred to as single generator operation) is preferable.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2016-55850

Disclosure of Invention

Problems to be solved by the invention

However, when it is assumed that 1 generator supplies electric power necessary for the operation of the propulsion system of the conventional mobile unit, the generator may trip due to an electric load (for example, a crane or the like) having a rapid fluctuation, and there is a risk of power failure. Therefore, when an electric load having a rapid fluctuation is used, it is necessary to operate an additional generator.

Alternatively, the power storage device may be connected to the power system via the power conversion device, and the generator and the power storage device may share the fluctuation amount of the electric power instead of the additional generator. However, in order to share most of the fluctuation amount with the power storage device, it is necessary to provide a power measuring means for each load to determine the fluctuation amount, and to control the power of the power conversion device at a high speed before the electromechanical system of the generator responds.

The present invention has been made to solve the above-described problems, and an object of the present invention is to enable a power system of a mobile body to be operated by 1 generator even when a power load having a rapid fluctuation is used by a simple method.

Means for solving the problems

In order to achieve the above object, an electric power distribution system for a mobile body according to an aspect of the present invention includes: a 1 st power system connected to a generator using a prime mover as a driving force and a 1 st power load in which a fluctuation amount of power consumed by or regenerated by the load (hereinafter, referred to as a power load fluctuation) is smaller than a predetermined value; a 2 nd power system connected to a 2 nd power load whose power load variation can be equal to or greater than the predetermined value; a 1 st power converter having an ac terminal connected to the 1 st power system and a dc terminal connected to a dc intermediate section; a 2 nd power converter having an ac terminal connected to the 2 nd power system and a dc terminal connected to the dc intermediate section; a 3 rd power converter having both dc ends connected to the dc intermediate portion and the power storage device, respectively; and a bus breaker that forms a parallel path to a power supply path from the 1 st power system to the 2 nd power system via the 1 st power converter and the 2 nd power converter, wherein the bus breaker is in a connected state when the 2 nd power load is not operated and is in a disconnected state when the 2 nd power load is operated, controls the 1 st power converter based on a 1 st power command value provided by a low-frequency component less than a predetermined frequency among actual power values passing through the 2 nd power converter, performs droop (drop) control on the 2 nd power converter, and controls power to the 3 rd power converter so as to cancel imbalance of power flowing into and out of the dc intermediate portion.

According to the above configuration, when the power load fluctuation (for example, the time rate of change of power, the amplitude of a predetermined frequency component of power, or the stepwise power fluctuation amount) can be set to the 2 nd power load operation which is equal to or greater than the predetermined value, the bus breaker is opened to put the 1 st power system and the 2 nd power system into the cutoff state. Thus, in the 1 st power system, the 1 st power load is directly supplied with power from the power generator, and the 2 nd power load is supplied with power through a power supply path from the 1 st power system to the 2 nd power system via the 1 st power converter and the 2 nd power converter. The power of the 2 nd power converter naturally changes according to the operating condition of the load. On the other hand, the 1 st power converter controls the flow of electric power from the generator to the dc intermediate portion. Further, the 3 rd power converter is controlled to absorb a difference in electric power flowing into and out of the dc intermediate portion. Thereby, the power difference between the 1 st power converter and the 2 nd power converter is automatically absorbed in the electrical storage device. When a sudden load variation occurs in the 2 nd power load, the 2 nd power converter is subjected to droop control, and therefore, the power supply to the 2 nd power load can be continued. Further, since the 1 st power converter is controlled based on the 1 st power command value supplied from the low frequency component smaller than the predetermined frequency in the actual power value of the 2 nd power converter, only the low frequency component smaller than the predetermined frequency in the power load fluctuation appears as power fluctuation in the 1 st power system, and the frequency component equal to or higher than the predetermined frequency is absorbed by the power storage device by the control of the 3 rd power converter. This suppresses the load fluctuation of the generator engine, and prevents the generator from tripping due to an abrupt load fluctuation. Accordingly, the magnitude of the load fluctuation of the generator engine can be set by adjusting only the predetermined frequency, so that the control adjustment can be easily performed, and it is not necessary to provide a power measuring means for each load.

On the other hand, when the 2 nd electric load is not operated, the bus breaker is closed to set the 1 st electric power system and the 2 nd electric power system to the connected state. Thus, a parallel path is formed with the power supply path from the 1 st power system to the 2 nd power system via the 1 st power converter and the 2 nd power converter. Since the droop control is performed on the 2 nd power converter, the droop control can be operated in cooperation with the generator (1 st power system). Even if the generator fails, power can be supplied from the power storage device by the effect of droop control, and power failure is not caused. Therefore, the power system of the mobile body can be operated by 1 generator regardless of whether or not the power load having a rapid fluctuation is operated.

According to the power distribution system of the mobile body, the droop control may be performed on the 2 nd power converter so as to be a point on a droop characteristic line indicating a relationship between the frequency of the 2 nd power system and the actual power value of the 2 nd power converter, and when the 2 nd power system is disconnected from the 1 st power system, the droop characteristic line may be adjusted so that the frequency of the 2 nd power system is set to a standard frequency, and when the 2 nd power system is connected to the 1 st power system, the droop control may be performed so that the power of the 2 nd power converter is set to 0kW and the frequency of the 2 nd power system is set to a standard frequency.

According to the above configuration, since the 2 nd power converter is controlled to droop so as to be a point on the droop characteristic line indicating the relationship between the frequency of the 2 nd power system and the actual power value of the 2 nd power converter, when the 2 nd power system including the 2 nd power load is disconnected from the 1 st power system to which the generator is connected, the frequency of the 2 nd power system fluctuates in accordance with the droop characteristic line with respect to a sudden fluctuation of the 2 nd power load. That is, the 2 nd power converter can function in the same manner as the generator in the autonomous operation. Further, the droop characteristic line can be adjusted so that the frequency after the fluctuation is set to the standard frequency, as in the case of the generator.

On the other hand, when the 2 nd power system is connected to the 1 st power system, the 2 nd power converter and the generator are operated in association with each other, and the droop characteristic line is adjusted, whereby the share rate of the steady load can be adjusted. In particular, when the steady load sharing rate of the 2 nd power converter is set to 0% (power 0 kW), the generator is responsible for consuming 100% of the power by the load in the steady state. This can suppress loss caused by the 2 nd power converter. On the other hand, when the power load fluctuates, both the 2 nd power converter and the generator fluctuate transiently according to the droop characteristic line. Therefore, only the fluctuation component of the power load can be shared by the 2 nd power converter and the generator. At this time, since the 2 nd power load is not operated from the beginning, there is no problem even if the generator takes charge of about half of the fluctuation component. Furthermore, even if the generator fails and is disconnected from the 1 st power system, the 2 nd power converter can supply power instead of the 1 st power system, and no power failure occurs. The electric power at this time is supplied from the power storage device. This means that the power storage device can be used as a backup power source via the 2 nd power converter and the 3 rd power converter in the present operation.

According to the power distribution system of the mobile body, the power distribution system of the mobile body may further include a 4 th power converter, the 4 th power converter being connected to the dc intermediate portion, an electric motor being connected to an ac end of the 4 th power converter, and a propeller being attached to a propeller shaft of the electric motor.

According to the above configuration, the present invention can be applied to an electric propulsion system for a mobile body.

The power distribution system of the mobile body may further include a 4 th power converter, the 4 th power converter being connected to the dc intermediate portion, a motor generator being connected to an ac end of the 4 th power converter, and a main unit and a propeller being attached to a propeller shaft of the motor generator.

According to the above configuration, the hybrid propulsion system can be applied to a hybrid propulsion system of a mobile body.

The 1 st power command value may be provided by a sum of a low-frequency component of the actual value of the 2 nd power converter which is smaller than a prescribed frequency and a low-frequency component of the actual value of the power of the 4 th power converter which is smaller than the prescribed frequency.

According to the above configuration, the 1 st power command value is provided by the sum of the low frequency component of the actual value of the 2 nd power converter and the low frequency component of the actual value of the power of the 4 th power converter, and therefore, for example, the influence on the 1 st power system due to the power fluctuation of the motor and the sudden load fluctuation of the 2 nd power load can be suppressed. In particular, in the case where the 2 nd load including a sharp variation does not operate and closes the bus breaker, the 1 st power command value may provide only a low frequency component of the power actual value of the 4 th power converter.

The 4 th power converter may be power-controlled based on a 4 th power command value, the 4 th power command value being a power command value of the motor generator obtained by rotation speed control based on a deviation between a rotation speed command value of the motor generator supplied from an operation console and an actual rotation speed of the motor generator, or a power command value of the motor generator supplied from an operation console.

According to the above configuration, the rotation speed command value or the electric power command value is supplied from the console, and the rotation speed control or the electric power control of the motor generator can be performed by the 4 th electric power converter.

The charging rate of the power storage device may be calculated based on the actual current value or the actual power value of the 3 rd power converter, the 1 st charge/discharge correction power command value and the 4 th charge/discharge correction power command value may be calculated so that the charging rate is charged or discharged within a predetermined range, the 1 st charge/discharge correction power command value may be added to the 1 st power command value, and the 4 th charge/discharge correction power command value may be added to the 4 th power command value.

The power difference between the 1 st power converter and the 2 nd and 4 th power converters is automatically absorbed by charging and discharging the power storage device. According to the above configuration, SOC (State of Charge) control of the power storage device can be realized by adding the 1 st Charge/discharge correction power command value and the 4 th Charge/discharge correction power command value to the actual value of the 3 rd power converter.

Effects of the invention

According to the present invention, the power system of the mobile body can be operated by 1 generator.

Drawings

Fig. 1 is a diagram schematically showing the configuration of a mobile unit having a power distribution system of a mobile unit according to embodiment 1 of the present invention.

Fig. 2 is a block diagram showing a structure of the control device of fig. 1.

Fig. 3 is a block diagram showing a configuration of the power control unit of fig. 2.

Fig. 4 is a block diagram showing a configuration of a power distribution system of a mobile body in a case where the circuit breaker (Tie breaker) of fig. 1 is opened.

Fig. 5 is a droop characteristic line used for droop (drop) control of the 2 nd power converter in the single operation.

Fig. 6 is a block diagram showing a configuration of a power distribution system of a mobile body in a case where the circuit breaker of fig. 1 is closed.

Fig. 7 is a droop characteristic line used for droop control of the 2 nd power converter in the cooperative operation.

Fig. 8 is a diagram schematically showing the configuration of a mobile unit having a power distribution system of the mobile unit according to embodiment 2 of the present invention.

Fig. 9 is a block diagram showing the configuration of the control device of fig. 8.

Fig. 10 is a block diagram schematically showing an example of the inside of the control device of fig. 9.

Fig. 11 is a block diagram schematically showing another example of the inside of the control device of fig. 9.

Fig. 12 is a diagram schematically showing the configuration of a mobile unit having a power distribution system of the mobile unit according to embodiment 3 of the present invention.

Detailed Description

Embodiments according to the present invention will be described below with reference to the drawings. In the following, the same or corresponding elements are denoted by the same reference numerals throughout the drawings, and redundant description thereof will be omitted.

(embodiment 1)

Fig. 1 is a diagram schematically showing the configuration of a mobile body including a power distribution system 100 of a mobile body according to embodiment 1 of the present invention. As shown in fig. 1, a power distribution system 100 of a mobile body includes one power generator 5, an electric load 7, a power conversion device 1, a power storage device 2, an alternating current bus (AC bus line) 8, a bus breaker 4, a control device 3, and a propulsion system 200.

The generator 5 is a main power source for supplying electric power to the electric load 7. The generator 5 supplies electric power used in the mobile body with the motor 6 as a driving force. When the variation in the electric power is very large, the electric power supply from the generator 5 may be cut off due to the engine trip.

The electric loads 7 include a 1 st electric load 7a and a 2 nd electric load 7b connected to the ac bus 8. The 1 st electrical load 7a is a device that consumes the electrical power supplied from the generator 5. The 1 st power load 7a is provided with a plurality of devices each of which does not include a sudden load variation of power. The 1 st power load 7a includes, for example, devices that operate continuously such as hotel loads (hotel loads) for lighting and air conditioning of ships, and devices that operate for a short time such as a winch and an engine starter of the main engine 70. The 2 nd power load 7b is a device consuming power, and is a device such as a crane that involves a sudden load fluctuation of power. These devices are connected to an ac bus 8. The phrase "including a sudden variation" refers to a case where the amount of change in the consumed power, such as the temporal change rate of the power, the amplitude of a predetermined frequency component of the power, or the stepwise power variation amount, is equal to or greater than a predetermined value. "not including a rapid fluctuation" means that these amounts are smaller than a predetermined value. The predetermined value may be determined based on information on the following performance against the load variation, which is presented by the engine manufacturer.

The ac bus 8 is a power supply path including a 1 st bus 8a and a 2 nd bus 8b, the 1 st bus 8a is connected to the generator 5, the 1 st power load 7a, and the power conversion device 1, and the 2 nd bus 8b is connected to the 2 nd power load 7b and the power conversion device 1. The 1 st bus 8a and the 2 nd bus 8b are connected or disconnected by the bus breaker 4. The bus breaker 4 is in a connected state when the 2 nd power load 7b is not operated, and is in a disconnected state when the 2 nd power load 7b is operated. In the present embodiment, the control device 3 controls the opening and closing of the bus breaker 4. Hereinafter, in the power distribution system 100 of the mobile object, the power system connected to the 1 st bus 8a is referred to as "1 st power system", and the power system connected to the 2 nd bus 8b is referred to as "2 nd power system". In other words, the bus breaker 4 can form a route that connects the 1 st power system (8 a) and the 2 nd power system (8 b) to each other in an openable/closable manner and is parallel to a power supply route from the 1 st power system (8 a) to the 2 nd power system (8 b) via the 1 st power converter 11 and the 2 nd power converter 12.

One terminal of the power conversion device 1 is connected to the 1 st power system (8 a), and the other terminal is connected to the 2 nd power system (8 b). Specifically, the power conversion device 1 includes a 1 st power converter 11, a 2 nd power converter 12, a 3 rd power converter 13, and a dc intermediate portion 9.

The 1 st power converter 11 adjusts power consumed from the 1 st power system (8 a). The 1 st power converter 11 is an AC-DC converter. The 1 st power converter 11 has an ac terminal connected to the 1 st power system (8 a), and the 1 st power converter 11 has a dc terminal connected to the dc intermediate section 9.

The 2 nd power converter 12 supplies power to the 2 nd power system (8 b). The 2 nd power converter 12 is an AC-DC converter. The dc end of the 2 nd power converter 12 is connected to the dc intermediate section 9, and the ac end of the 2 nd power converter 12 is connected to the 2 nd power system (8 b).

The 3 rd power converter 13 is a DC/DC converter that controls power to cancel imbalance of power flowing into and out of the DC intermediate portion 9. One dc end of the 3 rd power converter 13 is connected to the dc intermediate portion 9, and the other dc end of the 3 rd power converter 13 is connected to the power storage device 2.

The dc intermediate portion 9 is connected to a dc terminal of the 1 st power converter 11, a dc terminal of the 2 nd power converter 12, and one dc terminal of the 3 rd power converter 13.

The power storage device 2 is connected to the other dc terminal of the 3 rd power converter 13. The power storage device 2 is composed of, for example, a secondary battery and a capacitor. As the secondary battery, for example, a lithium ion battery, a nickel hydride battery, and a lead storage battery can be used. Examples of the capacitor include a lithium ion capacitor, an electric double layer capacitor, a Nano hybrid capacitor (Nano capacitor), and a carbon nanotube capacitor (carbon nanotube capacitor).

The power distribution system 100 of the present embodiment is applied to a ship (hereinafter, also referred to as a mechanically propelled ship) equipped with a mechanical propulsion system. In the mechanical propulsion ship, the propulsion system 200 has a main machine 70 as a main drive source of the propeller 80. The propeller 80 is a ship propeller. The main machine 70 is independent of the generator 5, and is configured to drive the propeller 80 only by thrust of the main machine 70. The configuration of the propulsion system 200A differs depending on the type of ship on which the power distribution system 100A is mounted, and examples thereof include a hybrid ship, an electric propulsion ship, and a mechanical propulsion ship on which a shaft generator is mounted.

The control device 3 includes a memory and an arithmetic device (both not shown), and controls the power conversion device 1, the opening and closing of the bus breaker 4, the generator 5, and the propulsion system 200. The control device 3 of the present embodiment controls each element of the moving body in accordance with the operation information from the console 40. As shown in the block diagram of fig. 2, the control device 3 includes a main control unit 30, a power control unit 31, a droop control unit 32, a charge/discharge control unit 33, and a droop control unit 35. These units are functions realized by executing a program stored in a memory in an arithmetic device. The functions of the power control unit 31, the droop control unit 32, the charge/discharge control unit 33, and the droop control unit 35 may be included in the programs of the computing device of the 1 st power converter 11, the computing device of the 2 nd power converter 12, the computing device of the 3 rd power converter 13, and the engine control device of the generator 5, respectively.

The main control unit 30 selects an operation mode of the propulsion system 200 based on operation information indicating a position of a joystick input from the joystick provided on the console 40, for example, and starts and stops the devices constituting the propulsion system 200. The main control unit 30 generates an opening/closing command for the bus breaker 4 in accordance with the operation mode of the mobile body, but the bus breaker 4 may be opened or closed directly by a driver, for example. Further, a part of the functions of the main control unit 30 may be included in a program of a power supply management system that manages the supply and demand of electric power to and from the ship. The main control unit 30 may start and stop the generator 5, or may start and stop the generator from the power management system. The power supply management system performs adjustment of a droop characteristic line and management of an actual power value of the power conversion device in droop control described later.

The power control unit 31 controls the 1 st power converter 11 so that the power converted by the 1 st power converter 11 becomes the 1 st power command value, based on the 1 st power command value supplied by the low frequency component smaller than the predetermined frequency out of the actual values of the power passing through the 2 nd power converter 12. The power control unit 31 includes a filter 311 (see the block diagram of fig. 3). The filter 311 is a low-pass filter or a moving average filter with a fixed time constant. The actual power value of the 2 nd power converter 12 is input from the main control unit 30, and the filter 311 passes only a low-frequency component of the actual power value of the 2 nd power converter 12, which is lower than a predetermined frequency, and outputs the component to the 1 st power converter 11 as the 1 st power command value.

The droop control unit 32 performs droop control on the 2 nd power converter 12. The "droop control" is control in which a model of a controller (governor) that controls the generator is built in the control device 3 so that the 2 nd power converter 12 has characteristics corresponding to the generator. The 2 nd power converter 12 has characteristics corresponding to a generator, and as a result, it is possible to seamlessly switch between autonomous operation and system cooperative operation. Since the "droop control" is a known technique, a detailed description thereof is omitted. For details of the "droop control", for example, refer to "g.marina & e.gatti," Large Power PWM IGBT Converter for lift alternators Systems ",35th annular IEEE Power Electronics standards conference,2004". In the "droop control", the frequency of the power system and the power (effective power) transmitted to or received from the power system by the 2 nd power converter 12 are detected by sensors, respectively, and are input to the droop control unit 32 to be used for these controls in the droop control.

The charge/discharge control unit 33 monitors the voltage of the dc intermediate portion 9 in the 3 rd power converter 13 based on sensor data from a voltage sensor and a current sensor (not shown), and performs charge/discharge control of the power storage device 2 so that the voltage of the dc intermediate portion 9 becomes a fixed value. The charge/discharge control unit 33 controls the charge/discharge of the power storage device 2 through the 3 rd power converter 13 according to the change in the voltage of the dc intermediate portion 9. Thereby, the difference between the electric power flowing into dc intermediate portion 9 and the electric power flowing out of dc intermediate portion 9 is absorbed by power storage device 2.

The droop control unit 35 detects the active power, obtains a frequency target value from the droop characteristic, and controls the rotation speed of the motor (engine, turbine, etc.) of the generator 5. The following speed of the frequency fluctuation with respect to the load fluctuation is determined based on mechanical characteristics such as the inertia of the generator.

Next, the operation of the power distribution system 100 for a mobile body will be described. The opening and closing of the bus breaker 4 is controlled in accordance with the operation mode of the movable body selected by the lever operation of the console 40 (see fig. 2). When a predetermined operation mode for operating the 2 nd power load 7b (e.g., a crane) is selected, the main control unit 30 generates an open command for the bus breaker 4 and transmits the command to the bus breaker 4. Fig. 4 is a block diagram showing a configuration of a power distribution system 100 of a mobile body in a case where the bus breaker 4 is opened. As shown in fig. 4, the 1 st power system (8 a) and the 2 nd power system (8 b) are disconnected from each other by the bus breaker 4. In the 1 st power system (8 a), the 1 st power load 7a is directly supplied with electric power from the generator 5, but since the 2 nd power system (8 b) is separated from the 1 st power system (8 a), the 2 nd power load 7b is supplied with electric power from the 1 st power system (8 a) via the 1 st power converter 11 and the 2 nd power converter 12.

At this time, the power supplied to the 2 nd power system (8 b) by the 2 nd power converter 12 changes in accordance with the operating condition of the 2 nd power load 7b, and accordingly, the frequency of the 2 nd power system (8 b) also changes. Specifically, the droop control unit 32 (see fig. 2) performs droop control on the 2 nd power converter 12. Hereinafter, the case where the bus breaker 4 is opened and the 2 nd power converter 12 operates independently of the generator 5 as shown in fig. 4 is referred to as a single operation. In the single operation, the generated power is determined according to the operating state of the load. Fig. 5 is a droop characteristic line used for droop control of the 2 nd power converter 12 in the single operation. As shown in fig. 5, the droop characteristic is a relationship between the effective power (positive during power generation) and the system frequency, and is set so that the system frequency is lower as the effective power is larger. The droop rate is defined by a value obtained by dividing the difference between the frequency at the rated load and the frequency at the no load by the rated frequency. Generally, the droop rates are set to the same value in the power sources, but may be set to different values as needed. The droop control unit 32 performs droop control on the 2 nd power converter 12 so as to be a point on a droop characteristic line indicating a relationship between the frequency of the 2 nd power system (8 b) and the actual power value of the 2 nd power converter 12.

Fig. 5 (a) is a droop characteristic line set in the steady state of the 2 nd power converter 12. As shown in fig. 5 a, in a steady state, when the 2 nd power converter 12 supplies power P1 to the 2 nd power system (8 b), the droop characteristic line (line indicated by x in the figure) causes the frequency corresponding to P1 to be the standard frequency (frequency target value) Fs.

Fig. 5 (b) shows a droop characteristic line in the case where a sudden load variation occurs in the 2 nd electric load 7b (e.g., a crane). Here, assume that the power supplied from the 2 nd power converter 12 to the 2 nd power system (8 b) increases from P1 to P2 due to a sudden load fluctuation. As shown in fig. 5 (b), the 2 nd power converter 12 reduces the frequency of the 2 nd power system (8 b) according to the droop characteristic line (x mark of (1) on the straight line). Thereafter, the power management system adjusts the droop characteristic line ((2) in the direction of the arrow) to return the reduced frequency of the 2 nd power system (8 b) to the target value, i.e., the standard frequency Fs.

Fig. 5 (c) is a droop characteristic line of the 2 nd power converter 12 newly set by the adjustment of the power management system. As shown in fig. 5 (c), in the new droop characteristic line, the frequency corresponding to P2 is set to be the standard frequency (frequency target value) Fs. Thus, even when a sudden load variation occurs in the 2 nd power load 7b (e.g., a crane), the 2 nd power converter 12 is subjected to droop control, and therefore the 2 nd power converter 12 can function in the same manner as a generator during autonomous operation. This enables the 2 nd power load 7b to continue to be supplied with power. In the standalone operation, since the power storage device 2 is a power source, load variation does not become a problem unlike the engine generator.

On the other hand, the 1 st power converter 11 adjusts the power consumed by the 1 st power system (8 a). Specifically, since the 1 st power converter 11 is controlled based on the 1 st power command value supplied by the low-frequency component smaller than the predetermined frequency in the actual power value of the 2 nd power converter 12, the power fluctuation of the low-frequency component smaller than the predetermined frequency appears as a load fluctuation in the 1 st power system, and the power fluctuation of the frequency component of the predetermined frequency or more is absorbed by the power storage device 2. This suppresses the load fluctuation when viewed from the generator 5, and prevents the generator 5 from tripping due to a sudden load fluctuation.

Next, the operation of the power distribution system 100 when a predetermined operation mode in which the 2 nd power load 7b (e.g., a crane) is not operated is selected will be described. Fig. 6 is a block diagram showing a configuration of a power distribution system 100 of a mobile body in a case where the bus breaker 4 is closed. As shown in fig. 6, the power distribution system 100 connects the 1 st power system (8 a) and the 2 nd power system (8 b) via the bus breaker 4. This forms a path parallel to a power supply path from the 1 st power system (8 a) to the 2 nd power system (8 b) via the 1 st power converter 11 and the 2 nd power converter 12. Hereinafter, a case where the bus breaker 4 is closed and the 2 nd power converter 12 and the generator 5 operate in cooperation is referred to as cooperative operation. In the cooperative operation, the power load sharing rate of the power generator or the power converter in the cooperative operation can be controlled. In the cooperative operation, the "1 st electric power system" and the "2 nd electric power system" are not distinguished from each other, but simply referred to as "electric power systems". Further, at the time of the cooperative operation, since the "2 nd electric load 7b" does not operate, the "1 st electric load 7a" and the "2 nd electric load 7b" are not distinguished, and are simply referred to as "electric loads".

Fig. 7 is a droop characteristic line used for droop control of the 2 nd power converter 12 and the generator 5 in the cooperative operation. The 2 nd power converter 12 is droop-controlled so as to be a point on a droop characteristic line indicating a relationship between the frequency of the power system and the actual power value of the 2 nd power converter 12. Similarly, the droop of the generator 5 is controlled so as to be a point on the droop characteristic line.

Fig. 7 (a) is a droop characteristic line set in the steady state of the 2 nd power converter 12 and the generator 5. As shown in fig. 7 (a), in the droop characteristic line of the 2 nd power converter 12, the power command value is set to 0kW (linear × mark) for the standard frequency (frequency target value) Fs of the power grid so that the 2 nd power converter 12 does not apply power to the power grid in a steady state. On the other hand, in the droop characteristic line of the generator 5, the power command value Pc1 (mark × on the straight line) is set to the standard frequency (frequency target value) Fs for the power system so that the generator 5 applies power to the power system in a steady state. Currently, since the power command value of the 2 nd power converter 12 is 0kW, the Pc1 matches the power of the load consumed by the power system. Fig. 7 (b) shows a droop characteristic line in the case where load fluctuation occurs in the power load 7. Here, a case is assumed where the electric load is reduced from Pc1 to Pc2. At this time, the operating point between the generator 5 and the power converter 12 is changed according to the droop characteristic line so that the sum of the generated power of the generator 5 and the generated power of the power converter 12 becomes Pc2. As shown in fig. 7 (b), the frequency increases, and the operating point of the 2 nd power converter 12 moves to the x mark of (1) on the straight line. In this case, the power converter 12 constitutes power consumption from the power grid. The following speed of the frequency fluctuation with respect to the load fluctuation is determined by the mechanical characteristics such as the inertia of the generator and the operation characteristics of the power converter. Then, the power management system adjusts the droop characteristic lines ((2) in the direction of the arrow) for returning the frequency of the increased power grid to the standard frequency Fs and returning the power of the power converter 12 to 0 Kw.

Fig. 7 (c) shows the droop characteristics of the newly set 2 nd power converter 12 and the generator 5. The droop characteristic line of the 2 nd power converter 12 changes transiently, but eventually, as shown in fig. 7 c, the droop characteristic line of the 2 nd power converter 12 returns to the original operating point (the power command value (0 kW), and the system frequency is the standard frequency Fs). In the new steady state, the generator 5 is responsible for 100% of the load power consumption (Pc 2). Thus, by adjusting the droop characteristic line so that the power of the 2 nd power converter 12 becomes 0kW, only the fluctuation component of the power load can be shared by the 2 nd power converter 12 and the power generator 5.

Thus, the 2 nd power converter operates in cooperation with the generator 5 by the droop control, and therefore, even when the generator 5 fails, power can be supplied to the power load 7, and therefore, a power failure does not occur. In this case, power converter 12 is operated alone, and can supply necessary electric power from power storage device 2.

Therefore, according to the present embodiment, in the electric power system of the mobile body, the power supply path to the electric power load 7 is switched by the bus breaker 4, and the electric power system of the mobile body can be operated by 1 generator regardless of whether or not the electric power load 7 having a rapid fluctuation is operated.

(embodiment 2)

Next, embodiment 2 will be explained. The configuration of the power distribution system of the mobile body of the present embodiment is the same as that of embodiment 1. Hereinafter, the same configurations as those of embodiment 1 will not be described, and only different configurations will be described.

Fig. 8 is a diagram schematically showing the configuration of a mobile unit having a power distribution system of the mobile unit according to embodiment 2 of the present invention. As shown in fig. 8, the power distribution system 100A is different from embodiment 1 (fig. 1) in that it is applied to a ship on which an electric propulsion system is mounted. Specifically, the power conversion device 1A further includes a 4 th power converter 14 connected to the dc intermediate portion 9, and the propulsion system 200A includes a motor generator 90 connected to an ac end of the 4 th power converter 14 and a propeller 80 attached to a propeller shaft of the motor generator 90 via a reduction gear 60.

In the electric propulsion ship, the motor generator 90 functions as a main drive source of the propeller 80. The motor generator 90 receives electric power from the generator 5 connected to the bus 8 via the 1 st power converter 11 and the 4 th power converter 14 to generate driving force, and gives the driving force to the propeller 80 to drive the propeller 80. In the electric propulsion ship, the motor generator 90 exclusively operates as a motor, but may also operate as a generator.

The 1 st power converter 11 is power-controlled based on the 1 st power command value, and the 4 th power converter 14 is power-controlled based on the 4 th power command value. The control device 3A includes a power control unit 31 that controls the 1 st power converter 11 and a power control unit 34 that controls the 4 th power converter 14 (see the block diagram of fig. 9).

Fig. 10 is a block diagram schematically showing an example of the inside of the control device 3A. As shown in fig. 10, the power control unit 31 of the 1 st power converter 11 includes a 1 st filter 311, a 2 nd filter 312, and an adder 313.

The 1 st filter 311 is a low pass filter or a moving average filter with a fixed time constant. The actual value of electric power of the 2 nd power converter 12 is input from the main control unit (30) to the 1 st filter 311. The 1 st filter 311 passes only a low frequency component smaller than a predetermined frequency out of the actual values of electric power of the 2 nd power converter 12, and outputs the low frequency component to the adder 313.

The 2 nd filter 312 is a low pass filter or a moving average filter with a fixed time constant. The actual value of the power of the 4 th power converter 14 is input from the power management system to the 2 nd filter. The 2 nd filter 312 passes only a low frequency component smaller than a predetermined frequency out of the actual values of electric power of the 4 th power converter 14, and outputs the low frequency component to the adder 313.

The adder 313 adds the low frequency component of the actual value of the 2 nd power converter 12 and the low frequency component of the actual value of the power of the 4 th power converter 14, and outputs the result to the 1 st power converter 11 as a 1 st power command value. The time constant of the 1 st filter 311 and the time constant of the 2 nd filter 312 may be the same or different.

According to the configuration of fig. 10, in addition to the effects of the above-described embodiment, since the 1 st electric power command value is supplied by the sum of the low frequency component of the actual value of the 2 nd electric power converter 12 and the low frequency component of the actual value of the electric power of the 4 th electric power converter 14, it is possible to suppress the influence on the 1 st electric power system (8 a) due to, for example, the electric power fluctuation of the motor generator 90 and the abrupt load fluctuation of the 2 nd electric power load 7b. In particular, when the 2 nd power load 7b including a rapid fluctuation is not operated and the bus breaker 4 is closed, the low frequency component of the actual power value of the 4 th power converter 14 may be set as the 1 st power command value.

As shown in fig. 10, the main control section 30 includes a 1 st lookup table 301 and a 2 nd lookup table 302.

Operation information (for example, a power saving command) indicating the position of the joystick input from the joystick provided on the console 40 is input to the 1 st lookup table 301. The 1 st lookup table 301 stores in advance the power command value of the motor generator 90 corresponding to the joystick position of the console 40, sets the power command value of the motor generator 90 corresponding to the joystick position based on the input operation information, and outputs the power command value to the power control unit 34 of the 4 th power converter 14.

Operation information (for example, a speed command) indicating the position of the joystick input from the joystick provided on the console 40 is input to the 2 nd lookup table 302. The 2 nd lookup table 302 stores in advance a rotation speed command value of the motor generator 90 corresponding to the joystick position of the console 40, sets the rotation speed command value of the motor generator 90 corresponding to the joystick position based on the input operation information, and outputs the rotation speed command value to the electric power control unit 34 of the 4 th electric power converter 14.

As shown in fig. 10, the power control unit 34 of the 4 th power converter 14 includes an adder-subtractor 341, a PID control unit 342, and a changeover switch 343.

The adder-subtractor 341 subtracts the actual rotation speed input by the rotation speed detection means (not shown) from the rotation speed command value of the motor generator 90 input from the 2 nd lookup table 302, and inputs the result to the PID control unit 342.

The PID control unit 342 performs proportional processing, integral processing, and differential processing on a deviation between the input rotation speed command value and the actual rotation speed of the motor generator 90 to generate an electric power command value for the motor generator 90, and outputs the electric power command value to the changeover switch 343. The integration process and the differentiation process may be omitted.

The selector switch 343 outputs any one of the electric power command value of the motor generator 90 set in the 1 st lookup table 301 and the electric power command value of the motor generator 90 generated by the PID control unit 342 to the 4 th electric power converter 14 as the 4 th electric power command value.

The changeover switch 343 is operable in accordance with a changeover instruction from the main control section 30.

Further, the changeover switch 343 is not provided, and only any one of the motor generator power command value and the motor generator rotational speed command value may be used.

Therefore, since the 4 th electric power command value is the electric power command value of the motor generator 90 obtained by the rotational speed control based on the deviation between the rotational speed command value of the motor generator 90 supplied from the console 40 and the actual rotational speed of the motor generator 90, or the electric power command value of the motor generator 90 supplied from the console 40, the rotational speed control or the electric power control of the motor generator 90 can be performed by the 4 th electric power converter 14 by supplying the rotational speed command value or the electric power command value from the console 40.

Fig. 11 is a block diagram schematically showing another example of the inside of the control device 3A. As shown in fig. 11, the control device 3A includes an SOC calculation unit 411, a charge/discharge power command value calculation unit 412, a power distribution calculation unit 413, an adder 414, and an adder 415.

The actual current value or the actual power value of the 3 rd power converter 13 is input from the power management system to the SOC calculation unit 411. The SOC calculation unit 411 calculates the state of charge of the power storage device 2 from the actual current value or actual power value of the 3 rd power converter 13, and outputs the state of charge to the charge/discharge power command value calculation unit 412.

The charge/discharge power command value calculation unit 412 calculates a charge/discharge power command value from the charging rate of the power storage device 2, and outputs the charge/discharge power command value to the power distribution calculation unit 413.

The power distribution calculation unit 413 calculates a 1 st charge/discharge correction power command value and a 4 th charge/discharge correction power command value based on the charge/discharge power command value so that the charging rate is within a predetermined range by performing charge/discharge, outputs the 1 st charge/discharge correction power command value to the adder 414, and outputs the 4 th charge/discharge correction power command value to the adder 415.

The adder 414 adds the 1 st charge-discharge correction power command value and the 1 st power command value, and outputs this to the 1 st power converter 11. The 1 st power command value may be the sum of the low frequency component of the actual value of the 2 nd power converter 12 and the low frequency component of the actual value of the power of the 4 th power converter 14 (the output value of the adder 313 in fig. 10), or may be a predetermined value.

The adder 415 adds the 4 th charge and discharge correction power command value and the 4 th power command value, and outputs it to the 4 th power converter 14. The 4 th power command value may be a value (output value of the changeover switch 343 in fig. 10) obtained from the rotation speed command value or the power command value from the console 40, or may be a predetermined value.

Therefore, according to the configuration of fig. 11, the SOC control of the power storage device 2 can be realized by adding the 1 st charge/discharge correction power command value and the 4 th charge/discharge correction power command value to the actual value of the 3 rd power converter 13.

(embodiment 3)

Next, embodiment 3 will be explained. The configuration of the power distribution system of the mobile body of the present embodiment is the same as that of embodiment 1. Hereinafter, the same configurations as those of embodiment 1 will not be described, and only different configurations will be described.

Fig. 12 is a diagram schematically showing the configuration of a mobile unit having a power distribution system of the mobile unit according to embodiment 3 of the present invention. As shown in fig. 12, the power distribution system 100B is different from embodiment 1 (fig. 1) in that it is applied to a ship on which a hybrid propulsion system is mounted. Specifically, the power conversion device 1A further includes a 4 th power converter 14 connected to the dc intermediate portion 9, and the propulsion system 200B includes a motor generator 90 connected to an ac end of the 4 th power converter 14, and a main machine 70 and a propeller 80 attached to a propulsion shaft of the motor generator 90 via a reduction gear 60.

In the hybrid ship, the main engine 70 functions as a main drive source of the propeller 80, and the motor generator 90 functions as an auxiliary drive source of the propeller 80. The motor generator 90 receives electric power from the generator 5 connected to the bus 8 via the 1 st power converter 11 and the 4 th power converter 14 to generate driving force, and provides the driving force to the propeller 80 to assist driving of the propeller 80 by the main machine 70. The motor generator 90 receives power from the main machine 70 to generate electric power, and supplies the generated electric power to the bus 8 via the 4 th power converter 14 and the 1 st power converter 11 to assist the electric power supply to the bus 8 by the generator 5. Alternatively, the generator 5 may be stopped and the motor generator 90 may be used as a main power source.

In the present embodiment, the "mobile body" is a ship, but is not particularly limited thereto, and may be a vehicle (such as a railway vehicle or an automobile), an airplane, or the like as long as it is a moving object. The "propeller" is not particularly limited as long as it is a device for propelling a moving object, and may be a wheel or a propeller for flight.

Many modifications and other embodiments of the invention will come to mind to one skilled in the art to which this invention pertains having the benefit of the teachings presented in the foregoing descriptions. Therefore, the foregoing description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the best mode of carrying out the invention. The details of one or both of the structure and function may be substantially changed without departing from the spirit of the present invention.

Industrial applicability

The present invention is applicable to an electric power system for a mobile body such as a ship.

Description of the reference symbols:

1. power conversion device

2. Electricity storage device

3. Control device

4. Bus circuit breaker

5. Generator

6. Motor

7. Electrical load

7a 1 st Electrical load (with sharp fluctuations)

7b No. 2 electric load (no sharp change)

8. Bus line

8a 1 st bus (1 st power system)

8b 2 nd bus (2 nd power system)

9. DC intermediate part

11. 1 st power converter

12. 2 nd power converter

13. 3 rd power converter

40. Operation desk

60. Speed reducer

70. Main unit

80. Propeller

90. Motor generator

100. Power distribution system for mobile body

Claims

1. A power distribution system for a mobile body, comprising:

a 1 st power system connected to a generator that uses a prime mover as a driving force and a 1 st power load, the 1 st power load being a load in which a fluctuation amount of power consumed by or regenerated by the load is smaller than a predetermined value;

a 2 nd power system connected to a 2 nd power load whose fluctuation amount can be equal to or greater than the predetermined value;

a 1 st power converter having an ac terminal connected to the 1 st power system and a dc terminal connected to a dc intermediate section;

a 2 nd power converter having an ac terminal connected to the 2 nd power system and a dc terminal connected to the dc intermediate section;

a 3 rd power converter having both dc terminals connected to the dc intermediate section and an electric storage device, respectively; and

a bus breaker that connects the 1 st power system and the 2 nd power system so as to be openable and closable, and that forms a path in parallel with a power supply path from the 1 st power system to the 2 nd power system via the 1 st power converter and the 2 nd power converter,

the bus breaker is brought into a connected state when the 2 nd electric load is not operated and brought into a disconnected state when the 2 nd electric load is operated,

the 1 st power converter is controlled based on a 1 st power command value supplied by a low-frequency component of the 2 nd power converter, the low-frequency component being less than a predetermined frequency, of the actual power value, the 2 nd power converter is controlled to droop, and the 3 rd power converter is controlled to remove imbalance of power flowing into and out of the dc intermediate portion.

2. The power distribution system of a mobile body according to claim 1,

droop-controlling the 2 nd power converter so as to be a point on a droop characteristic line indicating a relationship between a frequency of the 2 nd power system and an actual power value of the 2 nd power converter,

adjusting the droop characteristic line to set a frequency of the 2 nd power system to a standard frequency when the 2 nd power system is disconnected from the 1 st power system,

in a case where the 2 nd electric power system is connected to the 1 st electric power system, adjustment is made to set the electric power of the 2 nd electric power converter to 0kW, and set the frequency of the 2 nd electric power system to a standard frequency.

3. The power distribution system of the moving body according to claim 1 or 2, wherein the power distribution system of the moving body further has a 4 th power converter, the 4 th power converter being connected to the DC intermediate section,

an electric motor is connected to an ac end of the 4 th power converter, and a propeller is attached to a propeller shaft of the electric motor.

4. The power distribution system of the moving body according to claim 1 or 2, wherein the power distribution system of the moving body further has a 4 th power converter, the 4 th power converter being connected to the DC intermediate section,

a motor generator is connected to an ac end of the 4 th power converter, and a main unit and a propeller are attached to a propeller shaft of the motor generator.

5. The power distribution system of a mobile body according to claim 3,

the 1 st power command value is provided by a sum of a low-frequency component smaller than a predetermined frequency in the actual value of the 2 nd power converter and a low-frequency component smaller than a predetermined frequency in the actual value of the power of the 4 th power converter.

6. The power distribution system of a mobile body according to claim 3,

performing power control on the 4 th power converter based on the 4 th power command value,

the 4 th electric power command value is an electric power command value of the motor generator obtained by rotation speed control based on a deviation between a rotation speed command value of the motor generator supplied from an operation console and an actual rotation speed of the motor generator, or an electric power command value of the motor generator supplied from an operation console.

7. The power distribution system of the moving body according to claim 6,

calculating a charging rate of the electrical storage device based on the actual value of current or the actual value of electric power of the 3 rd electric power converter,

calculating a 1 st charge/discharge correction power command value and a 4 th charge/discharge correction power command value to perform charge/discharge so that a charging rate falls within a predetermined range,

adding the 1 st charge/discharge correction power command value to the 1 st power command value,

the 4 th charge/discharge correction power command value is added to the 4 th power command value.

8. The power distribution system of a mobile body according to claim 3,

the power distribution system of the mobile unit further includes a 4 th power converter, the 4 th power converter being connected to the DC intermediate section,

9. The power distribution system of a mobile body according to claim 4,

the 1 st power command value is provided by a sum of a low-frequency component of the actual value of the 2 nd power converter which is smaller than a predetermined frequency and a low-frequency component of the actual value of the power of the 4 th power converter which is smaller than the predetermined frequency.

10. The power distribution system of a mobile body according to claim 4,

the 4 th electric power command value is an electric power command value of the motor generator obtained by rotation speed control based on a deviation between a rotation speed command value of the motor generator supplied from a console and an actual rotation speed of the motor generator, or an electric power command value of the motor generator supplied from a console.

11. The power distribution system of a mobile body according to claim 5,

12. The power distribution system of a mobile body according to claim 10,

13. The power distribution system of a mobile body according to claim 11,