A data transmission method, comprising: receiving, at a gateway, sensor measurement data collected by at least one monitoring device in an electrical substation; storing the received sensor measurement data in a data storage that is accessible to the gateway in a predetermined format; detecting a status of a connection between the gateway and a first network, the first network enabling communication between the gateway and a server; and in response to detecting a disconnection between the gateway and the first network, sending the sensor measurement data to a user device via a second network hosted by the gateway to enable the user device to forward the sensor measurement data to the server; wherein the first network is a wide area access network, and the second network is a WI-FI network hosted by the gateway; the method further comprising: receiving, at the user device, the sensor measurement data from the gateway via the second network hosted by the gateway; detecting, a status of a connection between the user device and the first network, the first network enabling communication between the user device and the server; and in response to detecting that the user device is connected to the first network, sending, via the first network, a first request for an access to the server; and in response to receiving, via the first network, a first authorization to the first request from the server, sending the sensor measurement data to the server via the first network; and wherein receiving the sensor measurement data comprises: sending, via the second network, a request for the sensor measurement data to the gateway; and in response to receiving, via the second network, a second authorization to the second request from the gateway, receiving the sensor measurement data at the user device; and wherein receiving the sensor measurement data at the user device comprises: in response to receiving the second authorization that is based on a category and a geographical information associated with a user of the user device, receiving the sensor measurement data at the user device. receiving, at a gateway, sensor measurement data collected by at least one monitoring device in an electrical substation; storing the received sensor measurement data in a data storage that is accessible to the gateway in a predetermined format; detecting a status of a connection between the gateway and a first network, the first network enabling communication between the gateway and a server; and in response to detecting a disconnection between the gateway and the first network, sending the sensor measurement data to a user device via a second network hosted by the gateway to enable the user device to forward the sensor measurement data to the server; wherein the first network is a wide area access network, and the second network is a WI-FI network hosted by the gateway; receiving, at the user device, the sensor measurement data from the gateway via the second network hosted by the gateway; detecting, a status of a connection between the user device and the first network, the first network enabling communication between the user device and the server; and in response to detecting that the user device is connected to the first network, sending, via the first network, a first request for an access to the server; and in response to receiving, via the first network, a first authorization to the first request from the server, sending the sensor measurement data to the server via the first network; sending, via the second network, a request for the sensor measurement data to the gateway; and in response to receiving, via the second network, a second authorization to the second request from the gateway, receiving the sensor measurement data at the user device;