# US 11,309,706 B2 · Nano grid protection device, large power grid and a method for controlling a nano grid protection device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,309,706 B2 - Document ID: US11309706B2 - Status: Granted - Kind: B2 - Application number: 16/964,273 - Filed: 2019-02-06 - Published: 2021-02-04 - Granted: 2022-04-19 - Earliest claimed: 2018-02-06 - Assignees: Siemens Aktiengesellschaft - Applicants: Siemens Aktiengesellschaft - Inventors: Feng Du; Yi Zhu; Wei Gang Chen; Zhen Liu; Yue Zhuo - Web page: https://patentgrep.com/patent/US11309706B2 ## CPC - H02H 7/22: for distribution gear, e.g. bus-bar systems; for switching devices {(detecting mechanical or electrical defects in gas-insulated switchgears H02B13/065)} - H02H 7/28: for meshed systems - H02H 1/0007: {concerning the detecting means (in general G01R or other subclasses of G01; reed switches H01H71/2445)} - H02H 7/30: Staggered disconnection - H02H 3/027: with automatic disconnection after a predetermined time (H02H3/033, H02H3/06 take precedence {; timing in overcurrent protection circuits H02H3/093; in undervoltage protection circuits H02H3/247; staggered disconnection H02H7/30}) - H02H 3/033: with several disconnections in a preferential order, {e.g. following priority of the users, load repartition}(H02H3/06 takes precedence) - H02H: EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS (indicating or signalling undesired working conditions G01R, e.g. G01R31/00, G08B; locating faults along lines G01R31/08; emergency protective devices H01H) ## Abstract Provided is a nano grid protection device for a nano grid including a distributed power supply, a large power grid including the nano grid protection device, and a method for controlling the nano grid protection device. In an embodiment, the nano grid is connected with a bus through the nano grid protection device and a main grid is connected with the bus through a main grid protection device. In an embodiment, the nano grid protection device includes: a signal unit, configured to detect and send current information passing through the nano grid protection device, the current information including the magnitude and direction of the current; a controller, configured to determine, based upon the received current information, whether to send a trip signal or not; and an execution mechanism, configured to execute a trip operation of the nano grid protection device upon receiving the trip signal. ## Claims ### Claim 1 A nano grid protection device for a nano grid with a distributed power supply, the nano grid being connected with a bus through the nano grid protection device, and a main grid being connected with the bus through a main grid protection device, the nano grid protection device comprising: a signal unit, configured to detect and send current information passing through the nano grid protection device, the current information including a magnitude and direction of the current; a controller, configured to determine, based upon the current information received from the signal unit, whether to send a trip signal; and an execution mechanism, configured to execute a trip operation of the nano grid protection device upon receiving the trip signal from the controller, wherein upon a current flowing from the main grid to the nano grid, the signal unit is configured to determine the current as a forward current; and upon a current flowing from the nano grid to the main grid, the signal unit is configured to determine the current as a reverse current, and wherein upon the current being determined to be the reverse current, and upon the reverse current being determined to be continuously greater than a reverse current threshold within a delayed time period, the controller is configured to send the trip signal. ### Claim 2 (depends on 1) The nano grid protection device of claim 1, wherein the signal unit is configured to detect voltage information, the voltage information including a magnitude of a voltage. ### Claim 3 (depends on 2) The nano grid protection device of claim 2, wherein upon determining that the voltage is zero, the controller is configured to send the trip signal. ### Claim 4 (depends on 2) The nano grid protection device of claim 2, wherein upon a current flowing from the main grid to the nano grid, the signal unit is configured to determine the current as a forward current; and upon a current flowing from the nano grid to the main grid, the signal unit is configured to determine the current as a reverse current. ### Claim 5 (depends on 4) The nano grid protection device of claim 4, wherein upon the current being determined to be the forward current, and upon the forward current being determined to be greater than a forward current threshold, the controller is configured to send the trip signal. ### Claim 6 (depends on 5) The nano grid protection device of claim 5, wherein the controller is configured to send the trip signal after waiting for a trip time period, the trip time period being a trip time of an internal protection device inside the nano grid. ### Claim 7 (depends on 4) The nano grid protection device of claim 4, wherein upon the current being determined to be the reverse current, and upon the reverse current being determined to be continuously greater than a reverse current threshold within a delayed time period, the controller is configured to send the trip signal. ### Claim 8 (depends on 2) A large power grid, comprising: the at least one nano grid with the distributed power supply, each nano grid of the at least one nano grids being connected to the bus through at least one nano grid protection device; the branch circuit, connected to the bus through the at least one branch protection device; and the main grid, connected to the bus through the main grid protection device, wherein at least one nano grid protection device of the at least one nano grid protection device is the nano grid protection device of claim 2. ### Claim 9 (depends on 8) The large power grid of claim 8, wherein the branch circuit is the nano grid with the distributed power supply, and wherein the branch protection device is the at least one nano grid protection device. ### Claim 10 (depends on 1) The nano grid protection device of claim 1, wherein upon the current being determined to be the forward current, and upon the forward current being determined to be greater than a forward current threshold, the controller is configured to send the trip signal. ### Claim 11 (depends on 10) The nano grid protection device of claim 10, wherein the controller is configured to send the trip signal after waiting for a trip time period, the trip time period being a trip time of an internal protection device inside the nano grid. ### Claim 12 (depends on 10) The nano grid protection device of claim 10, wherein upon the current being determined to be the reverse current, and upon the reverse current being determined to be continuously greater than a reverse current threshold within a delayed time period, the controller is configured to send the trip signal. ### Claim 13 (depends on 1) The nano grid protection device of claim 1, wherein upon determining that the magnitude of the voltage received is reduced, the controller is configured to confirm that the reverse current is a reverse fault current. ### Claim 14 (depends on 1) The nano grid protection device of claim 1, wherein a branch circuit and the nano grid are connected in parallel to the bus through at least one branch protection device, the delayed time period being trip time of the branch protection device. ### Claim 15 (depends on 1) A large power grid, comprising: the at least one nano grid with the distributed power supply, each nano grid at least one nano grid being connected to the bus through at least one nano grid protection device; a branch circuit, connected to the bus through the at least one branch protection device; and the main grid, connected to the bus through the main grid protection device, wherein at least one nano grid protection device of the at least one nano grid protection device is the nano grid protection device of claim 1. ### Claim 16 (depends on 15) The large power grid of claim 15, wherein the branch circuit is the nano grid with the distributed power supply, and wherein the branch protection device is the at least one nano grid protection device. ### Claim 17 A method for controlling a nano grid protection device for a nano grid with a distributed power supply, the nano grid being connected with a bus through the nano grid protection device, a branch circuit and the nano grid being connected in parallel to the bus through at least one branch protection device, and a main grid being connected with the bus through a main grid protection device, the method comprising: receiving current information and voltage information passing through the nano grid protection device, the current information including a magnitude and a direction of the current, and the voltage information at least including a magnitude of a voltage; and determining, based upon the current information received or the current information and the voltage information received, whether to send a trip signal to an execution mechanism, wherein upon a current flowing from the main grid to the nano grid, the current is determined to be a forward current; and upon a current flowing from the nano grid to the main grid, the current is determined to be a reverse current, wherein the determining includes, upon the current direction being a reverse direction and upon the current being greater than a reverse current threshold, determining whether to send the trip signal, and upon the reverse current being continuously greater than the reverse current threshold within a delayed time period, sending the trip signal. ### Claim 18 (depends on 17) The method of claim 17, wherein upon a current direction being a forward direction and upon the current being greater than a forward current threshold, the trip signal is sent. ### Claim 19 (depends on 17) The method of claim 17, wherein the is sent after waiting for a trip time period, the trip time period being a trip time of an internal protection device inside the nano grid. ### Claim 20 (depends on 19) The method of claim 19, wherein the determining includes, upon the voltage being reduced, determining that the reverse current is a reverse fault current. ### Claim 21 (depends on 17) The method of claim 17, wherein the delayed time period is a trip time of the branch protection device. ### Claim 22 (depends on 17) The method of claim 17, wherein the determining includes, upon determining that the voltage is zero, sending the trip signal.