38results about How to "There is no detection blind zone" patented technology

The invention relates to the field of protection and control of micro-grids of electric power systems and particularly relates to a micro-grid island fast detection method. The method is sued for an inverter-based distributed generation (IBDG) with a PQ (power quest) decoupling control strategy; a corresponding reactive power control strategy is adopted in the method on the basis of measuring a voltage effective value UPCC and the load reactive power of a common coupling point PCC in real time through comparing the voltage effective value UPCC with the voltage effective value under a normal condition; when island determination is performed, firstly, a voltage threshold value and a frequency threshold value are predetermined, the voltage effective value UPCC is compared with the voltage threshold value, if the voltage effective value UPCC exceeds the threshold value, the PCC is directly determined be in an island state and the island detection is finished, and if the voltage effective value UPCC does not exceed the threshold value, the voltage frequency f of the PCC is compared with the frequency threshold value, the PCC is determined to be in the island state if the voltage frequency f of the PCC exceeds the threshold value. With the adoption of the detection method, the micro-grid island detection can be realized fast, and the effectiveness of the island detection can be ensured even under the existence of a plurality of inverter-based distributed generations.

The invention discloses a creeper tread quality test device, comprising an operation platform, a positioning device, a tension test device, a pressure test device, a traction device and a control device. The positioning device, the tension test device, the pressure test device and the traction device are sequentially arranged on the operation platform in line. The control device is arranged at one side of the operation platform and is connected with the pressure test device, the tension test device, and the traction device by a hydraulic pipeline and an electric pipeline. The invention can test creeper treads block by block, realizes production line style test process, improves test speed, and can simulate the actual stress condition of the creeper treads, thus the test result is precise and comprehensive without detection dead zone.

The invention provides a quick intelligent anti-island system and a quick intelligent anti-island method with power grid fault self-recovering capability. The method comprises the steps of a first step, establishing the main circuit of a distributed power generating grid-connected system; a second step, injecting phase angle fluctuation in the control circuit of the grid-connected system by an active phase deviation module; and a third step, based on the voltage signal of a common connecting point in the grid-connected system and a power grid frequency signal which is obtained by a phase-locked loop, realizing island detection and power grid fault self-recovering, wherein the common connecting point is the accessing position of a grid-connected filter and a local load into the power grid. The quick intelligent anti-island system and the quick intelligent anti-island method can quickly detect the island, and adding of additional hardware such as sensor is not required in the distributed power generating grid-connected system in which the phase-locked ring is used for realizing power grid synchronization. On the extreme condition that the system local load is a parallel RLC load which matches the power of the distributed power generating system, operation state of the island can be quickly and accurately detected. Furthermore no detection blind area exists and system operation efficiency can be effectively improved.

The invention discloses a DC micro-grid island detection method based on MPPT trapezoidal voltage disturbance. The steps are to start the MPPT strategy, set the start signal threshold of the disturbance, measure the output current value of the PVA at the maximum power operation, and calculate the same environmental coefficient of PVA with different capacities under the same light intensity and temperature in real time. When the environmental coefficient is greater than the set When the startup signal threshold of the disturbance is reached, the control performs periodic trapezoidal disturbance on the PVA port voltage reference value; the PCC voltage value U is detected pcc When it exceeds the threshold set by the passive method, it is judged as an isolated island, otherwise it is judged as U pcc The variation law of and the calculated value U of PCC voltage under trapezoidal disturbance pccp Whether the change rules of the islands are consistent; if they are consistent, it is an isolated island, otherwise it is a pseudo-isolated island. In the present invention, the active type and the passive type are combined to detect DC islands, and cooperate with each other, so there is no detection blind area.

The invention relates to a gene marker for detecting liver cancer and its application for hepatitis B patients. The present invention also relates to a method for detecting liver cancer using the gene marker.