# US 9,882,385 B2 · System for starting large-scale power load in micro-grid

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- Number: US 9,882,385 B2
- Document ID: US9882385B2
- Status: Granted
- Kind: B2
- Application number: 15/038,714
- Filed: 2014-06-24
- Published: 2016-10-06
- Granted: 2018-01-30
- Earliest claimed: 2013-11-22
- Assignees: State Grid Hebei Electric Power Research Institute; Hebei Electric Power Commissioning Institute; State Grid Corporation of China
- Applicants: State Grid Corporation of China; State Grid Hebei Electric Power Research Institute; Hebei Electric Power Commissioning Institute
- Inventors: Zhiqiang Gao; Liang Meng; Wenping Hu; Wenxin Wang; Hui Fan; Hao Jing; Bin Liang
- Web page: https://patentgrep.com/patent/US9882385B2

## CPC

- H02J 3/01: Arrangements for reducing harmonics or ripples
- H02J 3/32: using batteries or super capacitors with converting means
- H02J 3/381: {Dispersed generators}
- H02M 1/12: Arrangements for reducing harmonics from AC input or output
- H02M 7/44: by static converters
- H02J 2105/10: Local stationary networks having a local or delimited stationary reach
- Y02E 40/20: Active power filtering [APF]
- Y02P 80/14: District level solutions, i.e. local energy networks
- Y02P 80/15: On-site combined power, heat or cool generation or distribution, e.g. combined heat and power [CHP] supply
- H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P)
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

A system for staring a large-scale power load in a micro grid comprises a PCC grid connection switch, a micro grid alternating-current bus, an active power filter (APF), an energy storage inverter, an energy storage battery, a current-limiting resistor R, contactors K1-K3, a time relay KT, a power supply relay board, a micro grid maser control system, a frequency converter rectifying circuit, a frequency converter filter circuit, and a frequency converter inverter circuit. There are the advantages: an output torque of a power load can be effectively improved by using a variable frequency starting apparatus, and a starting current is also small; the provided method can effectively reduce a harmonic current when a variable frequency starting apparatus starts a power load, the phenomenon that two power sources supply power on a direct-current side of the variable frequency starting apparatus at the same time is avoided, thereby improving the stability and the economy of a micro grid.

## Claims

### Claim 1

A system for starting a large-scale power load in a micro-grid, comprising: PCC grid-connection switch, a micro-grid AC bus, an active power filter (APF), a battery storage inverter, an energy storage battery, a current-limiting resistor R, contactors K1-K3, a time relay KT, a power relay board, a micro-grid main control system, a rectifier circuit of converter, a filter circuit of converter, and an inverter circuit of converter, wherein, the micro-grid AC bus is bi-directionally connected with a bulk grid through the PCC grid-connection switch; the active power filter (APF) is bi-directionally connected with the micro-grid AC bus;
the energy storage battery comprises two branches, wherein one branch is bi-directionally connected with the micro-grid AC bus through the battery storage inverter, and the other branch is connected to the input terminal of the filter circuit of converter through main contact pins 1 and 2 of the contactor K3 and main contact pins 1 and 2 of the contactor K1 sequentially; the current-limiting resistor R is connected in parallel with main contact pins 1 and 2 of the contactor K1;
the micro-grid AC bus is connected to the large-scale power load through the rectifier circuit of converter, main contact pins 1 and 2 of the contactor K2, the filter circuit of converter, and the inverter circuit of converter sequentially;
a first control output terminal and a second control output terminal of the micro-grid main control system are connected to a first control input terminal I1 and a second control input terminal I2 of the power relay board respectively;
a first power output terminal E1-1 of the power relay board is connected to a common output terminal E1-01 of the power relay board through power supply coil terminals A1 and A2 of the contactor K3 and normally closed auxiliary contact pins 5 and 6 of the contactor K2 sequentially;
a second power output terminal E1-2 of the power relay board is connected to the common output terminal E1-01 of the power relay board through power supply coil terminals A1 and A2 of the contactor K2, normally closed auxiliary contact pins 5 and 6 of the contactor K3, and normally closed auxiliary contact pins 5 and 6 of the contactor K1 sequentially;
a third power output terminal E1-3 of the power relay board is connected to the common output terminal E1-01 of the power relay board through power terminal pins 1 and 2 of the time relay KT and normally open auxiliary contact pins 7 and 8 of the contactor K3 sequentially;
a fourth power output terminal E1-4 of the power relay board is connected to the common output terminal E1-01 of the power relay board through power supply coil terminals A1 and A2 of the contactor K1 and normally open contact pins 3 and 4 of the time relay KT sequentially.

### Claim 2 (depends on 1)

The system for starting a large-scale power load in a micro-grid according to claim 1, wherein, the power relay board comprises resistors R1-R2, photoelectric couplers OC1-OC2, relays J4-J5, DC power sources DC1-DC2, and AC power source E1;
the first input control terminal I1 of the power relay board is connected to the positive electrode pin 1 of an LED of the photoelectric coupler OC1 through the resistor R1; the negative electrode pin 2 of the LED of the photoelectric coupler OC1 is grounded; a collecting electrode pin 4 of the photoelectric coupler OC1 is connected to the positive electrode of a coil J4-1 of the relay J4, and an emitting electrode pin 3 of the photoelectric coupler OC1 is connected to the negative electrode of the coil J4-1 of the relay J4 through the DC power source DC1; a normally open stationary contact of the relay J4 is connected to the first power output terminal E1-1 of the power relay board, and a normally open moving contact of the relay J4 is connected to a terminal E1-02 of the AC power source E1;
the second input control terminal I2 of the power relay board is connected to the positive electrode pin 1 of an LED of the photoelectric coupler OC2 through the resistor R2; the negative electrode pin 2 of the LED of the photoelectric coupler OC2 is grounded; a collecting electrode pin 4 of the photoelectric coupler OC2 is connected to the positive electrode of a coil J5-1 of the relay J5, and an emitting electrode pin 3 of the photoelectric coupler OC2 is connected to the negative electrode of the coil J5-1 of the relay J5 through the DC power source DC2; a normally open stationary contact of the relay J5 is connected to the second power output terminal E1-2 of the power relay board, and a normally open moving contact of the relay J5 is connected to the terminal E1-02 of the AC power source E1;
the third power output terminal E1-3 of the power relay board and the fourth power output terminal E1-4 of the power relay board are connected to the terminal E1-02 of the AC power source E1 respectively; the terminal E1-01 of the AC power source E1 is the common output terminal E1-01 of the power relay board3.

### Claim 3 (depends on 2)

The system for starting a large-scale power load in a micro-grid according to claim 2, wherein, both of the photoelectric couplers OC1-OC2 are of model TLP521-1; both of the relays J4-J5 are of model MY2NJ-12VDC.

### Claim 4 (depends on 1)

The system for starting a large-scale power load in a micro-grid according to claim 1, wherein, the rectifier circuit of converter is a three-phase full-wave bridge circuit composed of rectifier diodes D1-D6.

### Claim 5 (depends on 4)

The system for starting a large-scale power load in a micro-grid according to claim 4, wherein, all of the rectifier diodes D1-D6 are of model SKD110/12E.

### Claim 6 (depends on 1)

The system for starting a large-scale power load in a micro-grid according to claim 1, wherein, the filter circuit of converter is a LC filter circuit composed of an inductor L and a capacitor C.

### Claim 7 (depends on 1)

The system for starting a large-scale power load in a micro-grid according to claim 1, wherein, the inverter circuit of converter is a three-phase full-bridge inverter circuit composed of IGBT modules Q1 -Q6 and diodes D7-D12; the power storage inverter is a three-phase full-bridge inverter circuit composed of IGBT modules Q7-Q12 and diodes D13-D18.

### Claim 8 (depends on 7)

The system for starting a large-scale power load in a micro-grid according to claim 7, wherein, all of the IGBT modules Q1 -Q12 are of model FS450R12KE3 from Infineon.

### Claim 9 (depends on 1)

The system for starting a large-scale power load in a micro-grid according to claim 1, wherein, the time relay KT is of model JS14P from Chint; the micro-grid main control system is of model NMC1000; the PCC grid-connection switch is of model MG2312; the active power filter (APF) is of model SPA3-100A/0.4.

### Claim 10 (depends on 2)

The system for starting a large-scale power load in a micro-grid according to claim 2, wherein, the time relay KT is of model JS14P from Chint; the micro-grid main control system is of model NMC1000; the PCC grid-connection switch is of model MG2312; the active power filter (APF) is of model SPA3-100A/0.4.

### Claim 11 (depends on 3)

The system for starting a large-scale power load in a micro-grid according to claim 3, wherein, the time relay KT is of model JS14P from Chint; the micro-grid main control system is of model NMC1000; the PCC grid-connection switch is of model MG2312; the active power filter (APF) is of model SPA3-100A/0.4.

### Claim 12 (depends on 4)

The system for starting a large-scale power load in a micro-grid according to claim 4, wherein, the time relay KT is of model JS14P from Chint; the micro-grid main control system is of model NMC1000; the PCC grid-connection switch is of model MG2312; the active power filter (APF) is of model SPA3-100A/0.4.

### Claim 13 (depends on 5)

The system for starting a large-scale power load in a micro-grid according to claim 5, wherein, the time relay KT is of model JS14P from Chint; the micro-grid main control system is of model NMC1000; the PCC grid-connection switch is of model MG2312; the active power filter (APF) is of model SPA3-100A/0.4.

### Claim 14 (depends on 6)

The system for starting a large-scale power load in a micro-grid according to claim 6, wherein, the time relay KT is of model JS14P from Chint; the micro-grid main control system is of model NMC1000; the PCC grid-connection switch is of model MG2312; the active power filter (APF) is of model SPA3-100A/0.4.

### Claim 15 (depends on 7)

The system for starting a large-scale power load in a micro-grid according to claim 7, wherein, the time relay KT is of model JS14P from Chint; the micro-grid main control system is of model NMC1000; the PCC grid-connection switch is of model MG2312; the active power filter (APF) is of model SPA3-100A/0.4.

### Claim 16 (depends on 8)

The system for starting a large-scale power load in a micro-grid according to claim 8, wherein, the time relay KT is of model JS14P from Chint; the micro-grid main control system is of model NMC1000; the PCC grid-connection switch is of model MG2312; the active power filter (APF) is of model SPA3-100A/0.4.