DC power distribution system load test method

Abstract

The invention discloses a load test method for a direct-current power distribution system. Comprising a direct-current distribution board, a standby generator set and a main propulsion motor. Two direct-current busbars are arranged in the direct-current distribution board and are connected through a direct-current solid-state switch; the two direct-current busbars are both connected with a rectifier module, the standby generator set comprises two standby generators, and the two standby generators are both connected to the rectifier module; the direct current busbar is connected with two main propulsion inversion modules, the two main propulsion inversion modules are both connected to a propulsion motor, and the propulsion motor is sequentially connected with a propulsion gearbox and a propulsion device; the test process comprises the following steps: completely immersing the propeller; the ship is kept in a static state; carrying out a single generator load test and a generator parallel test; the main push motor rotating speed corresponding to each required load working condition is obtained; and the main propulsion motor reaches a specified rotating speed through a handle of the main propulsion control system, so that the power of the main propulsion motor reaches the power of the load required by the test. The method is low in cost and less in field operation.

Description

Technical Field

[0001] The invention relates to the technical field of shipbuilding, and in particular to a method for load testing a direct current power distribution system. Background Art

[0002] In the shipbuilding industry, after a new ship is completed, the ship's generator must undergo a load test and be submitted to the shipowner and the ship inspector for inspection. Existing generator load tests all use dry loads or water loads to test the various performance and parameters of the generator.

[0003] The existing 700TEU pure electric container ship is mainly powered by a box-type power supply during normal navigation. Two backup generators are configured as emergency power supply equipment. The backup generator uses an asynchronous generator with a rated voltage of AC690V and a rated power of 900KW. It is connected to the DC busbar through the AC / DC rectifier module of the DC distribution board, and then outputs AC660V to the main propulsion motor after the inverter module of the main propulsion motor panel.

[0004] It is now necessary to carry out load tests on the two standby generators. If the dry load test method is adopted, two sets of dry loads are required. The rated voltage of the dry load is AC660V and the rated power is 1000KW. They are connected to the main propulsion motor panel of the DC distribution board as the load for the generator load test.

[0005] The inverter module is inside the main propulsion panel of the DC distribution board. The rear end of the inverter module must be connected to a series resistive inductive load. If a resistive load or a parallel resistive inductive load is connected, the PWM wave output by the inverter module under full power conditions will cause large harmonics at the front end of the resistive load, and the dudt on the output side of the inverter module will heat up severely.

[0006] Connecting dry loads also requires a large number of frequency conversion cables, and the dry loads and frequency conversion cables in this method are non-standard products and need to be customized and rented, which is expensive. Summary of the invention

[0007] The purpose of the present invention is to provide a method for load testing of a DC power distribution system by using a propulsion device to perform load testing, avoid the heating problem of using a dry load, save costs, and reduce on-site workload in view of the shortcomings of the prior art.

[0008] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a method for load testing of a DC power distribution system, comprising a DC distribution board, a standby generator set and a main propulsion motor; a first DC busbar and a second DC busbar are provided in the DC distribution board, and the first DC busbar and the second DC busbar are connected through a DC solid-state switch; the first DC busbar is connected to a first rectifier module, and the second DC busbar is connected to a second rectifier module; the standby generator set comprises a first standby generator and a second standby generator, the first standby generator is connected to the first rectifier module, and the second standby generator is connected to the second rectifier module; the first DC busbar is connected to a first main propulsion inverter module, and the second DC busbar is connected to a second main propulsion inverter module; the main propulsion motor comprises a first propulsion motor and a second propulsion motor, the first propulsion motor is connected to the first main propulsion inverter module, the second propulsion motor is connected to the second main propulsion inverter module, the first main propulsion inverter module is sequentially connected to a first propulsion gearbox and a first propulsion device, and the second main propulsion inverter module is sequentially connected to a second propulsion gearbox and a second propulsion device;

[0009] The test consists of the following steps:

[0010] Fully immerse the propeller in the test waters; ensure that the ship remains stationary by fastening it to the cable dock or pushing it with a tugboat; conduct a single generator load test and a generator parallel test; refer to the main propulsion motor speed-power curve obtained from the ship model test to calculate the main propulsion motor speed corresponding to each load condition required in the load test; use the main propulsion control system handle to make the main propulsion motor reach the specified speed so that the power of the main propulsion motor reaches the power of the load required for the test. It needs to be further explained that according to national standards, during the generator load test, data records are required for 0.25, 0.25, 0.50, 2, and 0.50 hours of operation in 5 states of 25%, 50%, 75%, 100%, and 110% respectively. During the generator parallel test, since the ship is in a fixed state at the dock during the test, the main propulsion motor cannot reach the rated power, and the capacity of the two standby generators in parallel is 1800KW, the power of the main propulsion motor cannot reach 100% of the capacity of the standby generator. When using the standby generator, the power of the main propulsion motor will be limited, and there will be no 100% load condition when the generator is in parallel. Referring to the AC power load calculation book, the maximum load of the generator in the navigation state using the standby generator is 80%; during the generator parallel test, first start a standby generator to load the operating unit to 360KW load, start another standby generator to connect to the grid, and after the load distribution is completed, change the speed of the main propulsion motor to make the total load on the grid reach 80% as much as possible, and record the active power and current of the rectifier cabinet.

[0011] Preferably, the first standby generator and the second standby generator are both asynchronous generators with a rated voltage of 690V and a rated power of 900KW; the rated power of the first rectifier module and the second rectifier module are both 900KW.

[0012] Preferably, the rated power of the first main propulsion inverter module and the second main propulsion inverter module are both 900KW, and the rated power of the first propulsion motor and the second propulsion motor are both 900KW.

[0013] Preferably, the rated voltage of the first DC busbar and the second DC busbar is 1000V, and the rated current of the DC solid-state switch is 2000A.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] 1. Avoid equipment rental of dry loads and frequency conversion cables to save costs;

[0016] 2. Avoid dismantling and replacing the frequency conversion cable of the main motor panel of the DC distribution board, reduce a lot of labor costs, simplify the test process, and reduce on-site workload;

[0017] 3. Verify the performance of the main propulsion motor in advance, and discover and solve problems in advance through the operation of the main propulsion motor to avoid affecting the navigation test. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of the present invention.

[0019] Among them, 1-DC distribution board, 11-first rectifier module, 12-second rectifier module, 13-first main propulsion inverter module, 14-second main propulsion inverter module, 31-first propulsion motor, 32-first propulsion gearbox, 33-first propulsion device, 34-second propulsion device, 35-second propulsion gearbox, 36-second propulsion device. DETAILED DESCRIPTION

[0020] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention. After reading the present invention, various equivalent forms of modifications to the present invention by those skilled in the art all fall within the scope defined by the claims attached to this application.

[0021] like Figure 1The method for load test of a DC power distribution system shown in the figure includes a DC distribution board 1, a standby generator set and a main propulsion motor; a first DC busbar and a second DC busbar are arranged in the DC distribution board 1, and the first DC busbar and the second DC busbar are connected by a DC solid-state switch, the rated voltages of the first DC busbar and the second DC busbar are both 1000V, and the rated current of the DC solid-state switch is 2000A; the first DC busbar is connected to a first rectifier module 11, and the second DC busbar is connected to a second rectifier module 12, the standby generator set includes a first standby generator and a second standby generator, both of which are asynchronous generators, with a rated voltage of 690V and a rated power of 900KW; the rated powers of the first rectifier module 11 and the second rectifier module 12 are both 900KW, and the first standby generator The first main propulsion inverter module 13 is connected to the first DC busbar, and the second main propulsion inverter module 14 is connected to the second DC busbar. The main propulsion motor includes a first propulsion motor 31 and a second propulsion motor. The first propulsion motor 31 is connected to the first main propulsion inverter module 13, and the second propulsion motor is connected to the second main propulsion inverter module 14. The rated power of the first main propulsion inverter module 13 and the second main propulsion inverter module 14 is both 900KW. The rated power of the first propulsion motor 31 and the second propulsion motor is both 900KW. The first main propulsion inverter module 13 is sequentially connected to the first propulsion gearbox 32 and the first propulsion device 33, and the second main propulsion inverter module 14 is sequentially connected to the second propulsion gearbox 35 and the second propulsion device 3634;

[0022] The two standby generators provide AC power which is rectified by the rectifier module and then connected to the grid, and supplies power to the propulsion motor via the main propulsion inverter module in the DC distribution board 1.

[0023] The test consists of the following steps:

[0024] Fully immerse the propeller in the test waters; ensure that the ship remains stationary by fastening it to the cable dock or pushing it with a tugboat; conduct a single generator load test and a generator parallel test; refer to the main propulsion motor speed-power curve obtained from the ship model test to calculate the main propulsion motor speed corresponding to each load condition required in the load test; use the main propulsion control system handle to make the main propulsion motor reach the specified speed so that the power of the main propulsion motor reaches the power of the load required for the test.

[0025] According to national standards, the generator load test needs to be carried out at 25%, 50%, 75%, 100%, and 110%, and the data records are run for 0.25, 0.25, 0.50, 2, and 0.50 hours respectively. During the generator parallel test, because the ship is in a fixed state at the dock during the test, the main propulsion motor cannot reach the rated power, and the capacity of the two standby generators in parallel is 1800KW, and the power of the main propulsion motor cannot reach 100% of the capacity of the standby generator. When using the standby generator, the power of the main propulsion motor will be limited, and there will be no 100% load condition when the generator is in parallel. Referring to the AC power load calculation book, the maximum load of the generator in the navigation state using the standby generator is 80%; during the generator parallel test, first start a standby generator to load the operating unit to 360KW load, start another standby generator to connect to the grid, and after the load distribution is completed, change the speed of the main propulsion motor to make the total load on the grid reach 80% as much as possible, and record the active power and current of the rectifier cabinet.

[0026] The above description shows and describes the preferred embodiments of the present invention. As mentioned above, it should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the invention concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art do not depart from the spirit and scope of the present invention, and should be within the scope of protection of the claims attached to the present invention.

Claims

1. A method for load testing of a DC power distribution system, characterized in that: It includes a DC distribution board, a standby generator set and a main propulsion motor; a first DC busbar and a second DC busbar are provided in the DC distribution board, and the first DC busbar and the second DC busbar are connected through a DC solid-state switch; the first DC busbar is connected to a first rectifier module, and the second DC busbar is connected to a second rectifier module; the standby generator set includes a first standby generator and a second standby generator, the first standby generator is connected to the first rectifier module, and the second standby generator is connected to the second rectifier module; the first DC busbar is connected to a first main propulsion inverter module, and the second DC busbar is connected to a second main propulsion inverter module; the main propulsion motor includes a first propulsion motor and a second propulsion motor, the first propulsion motor is connected to the first main propulsion inverter module, and the second propulsion motor is connected to the second main propulsion inverter module, the first main propulsion inverter module is sequentially connected to a first propulsion gearbox and a first propulsion device, and the second main propulsion inverter module is sequentially connected to a second propulsion gearbox and a second propulsion device; The test consists of the following steps: Fully immerse the propeller in the test waters; ensure that the ship remains stationary by fastening it to the cable dock or pushing it with a tugboat; conduct a single generator load test and a generator parallel test; refer to the main propulsion motor speed-power curve obtained from the ship model test to calculate the main propulsion motor speed corresponding to each load condition required in the load test; use the main propulsion control system handle to make the main propulsion motor reach the specified speed so that the power of the main propulsion motor reaches the power of the load required for the test.

2. The DC power distribution system load test method according to claim 1, characterized in that: The first standby generator and the second standby generator are both asynchronous generators with a rated voltage of 690V and a rated power of 900KW; the rated powers of the first rectifier module and the second rectifier module are both 900KW.

3. The DC power distribution system load test method according to claim 1, characterized in that: The rated power of the first main propulsion inverter module and the second main propulsion inverter module are both 900KW, and the rated power of the first propulsion motor and the second propulsion motor are both 900KW.

4. The DC power distribution system load test method according to claim 1, characterized in that: The rated voltages of the first DC busbar and the second DC busbar are both 1000V, and the rated current of the DC solid-state switch is 2000A.

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