Self-adaptive zero-time difference over-current protection method
A zero-time-difference, self-adaptive technology, applied in the direction of automatically disconnected emergency protection devices, emergency protection circuit devices, electrical components, etc., can solve the problems of operation mode influence, failure to meet sensitivity coefficient or protection device range, complex structure, etc. Achieve the effects of reducing labor management costs, high reliability, and simple system structure
Active Publication Date: 2013-06-12
XI AN JIAOTONG UNIV
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Problems solved by technology
Although this protection method solves the problems existing in the definite time overcurrent protection device, the structure is complex and is seriously affected by the grid connection and power system operation mode.
For example, its setting value must be set according to the maximum operating mode of the system, while the sensitivity must be verified using the minimum operating mode of the system, which makes it unable to meet the requirements of the sensitivity coefficient or the range of protection devices
Method used
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[0031] According to the above technical scheme, the adaptive zero-time difference overcurrent protection method equips each protection device with a monitoring unit, and all physically directly connected protection devices can communicate in real time through Ethernet, such as figure 2 Shown by the dotted line. Its working process is as follows:
[0032] The current and voltage in the power line are input to the microprocessor through the analog signal acquisition and conditioning module. When a short-circuit fault occurs on the line, the microprocessor starts timing and notifies the upper-level adjacent circuit breaker of the circuit breaker that there is a fault through the Ethernet, and at the same time detects whether there is a notification from the lower-level adjacent circuit breaker. If notified by the adjacent circuit breaker at the lower level, the microprocessor sets the action time limit as t i +Δt. If no notification is received, set the action time limit to t...
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The invention discloses a self-adaptive zero-time difference over-current protection method which is characterized in that the same inherent time limit (ti) is set for all protection devices in a power grid, and the protection devices can communicate via the Ethernet; when a protection device detects short-circuit current, the protection device immediately notifies an adjacent protection device at a higher level and meanwhile defects whether a notice from the adjacent protection device at a lower level comes or not; if the notice is received, an action time limit is set to be ti plus preset time (Dt), so as to play a backup protection role; and if the notice is not received, the action time limit is set to be ti so as to cut off a fault. The protection devices have a self-adaptive logic positioning function; when the topology of the power grid is changed, all the protection devices automatically communicate with the potential adjacent protection devices at the higher levels which are recorded in the devices, the currently actual adjacent protection device at the higher level is determined according to the state of the adjacent protection device at the higher level which is fed back, so as to establish the logic relationship between higher and lower levels among all the protection devices, and actively adapt to the changes of the topology of the power grid.
Description
technical field [0001] The invention relates to an overcurrent protection method of a power grid, in particular to an adaptive zero-time difference overcurrent protection method. Background technique [0002] Grid security is affected by many factors, and failures are inevitable. When a fault occurs, it is generally accompanied by an abnormal increase in current, so overcurrent protection is a direct and effective method for detecting and removing faults in the power grid. The overcurrent protection device is a protection device whose starting current is set according to avoiding the maximum load operating current. It does not start when the power grid is in normal operation, but when a fault occurs, it can respond to abnormal current and act. Under normal circumstances, it can not only protect the entire length of the current line, but also protect the entire length of adjacent lines, and play a role of backup protection. [0003] The traditional overcurrent protection me...
Claims
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IPC IPC(8): H02H7/26H02H3/093
Inventor 张爱民任志刚张杭耿英三
Owner XI AN JIAOTONG UNIV