An error compensation method for the single pair-pole encoder has been discussed in this paper. This article analyzed offset, sensitivity error, quadrature error and ferromagnetic interference error of single-pole magnetic encoder to obtain the expression of each error. In order to facilitate error compensation, the common expression for describing the error has been summed up. The process for formatting the error can be assumed as the process of changing from circle to ellipse. Therefore the inverse of this process is the same as the process of error compensation. The experimental results show that the accuracy of magnetic encoder which used this method could reach ±1, thus the error compensation effect is obvious. The magnetic encoder which applied this method has the advantages of low-cost, high-precision and convenient to use.

A new fast busbar protection algorithm based on the comparison of the similarity of back-wave waveforms is proposed in this paper. The S-transform is performed on the back-wave from each defected transmission line connected to the busbar, and the protection criterion is thus constructed by using the Euclidean distance to analyze the similarity of the back-waves, with the implementation of the S-transform between the transmission lines. When a fault occurs internally on the busbar, the Euclidean distance of the S-transformed back-wave between each associated transmission line is small, and there is a remarkable similarity between the waveform. When a fault occurs externally on the busbar, the Euclidean distance of the S-transformed backward traveling wave between the faulty line and the nonfaulty line is larger than that between the nonfaulty lines. The wave-forms of the faulty line and the nonfaulty line bear little similarity, while there is a striking similarity between the nonfaulty lines. Therefore, a protection criterion is established according to the ratio between the maximal similarity and the minimal similarity to discriminate the internal and external faults of the busbar zones. The simulation results show that the proposed busbar protection method can discriminate the internal and external faults of busbar zones in a sensitive and reliable way.

Based on the problems of traditional broadcast system such as complexity wiring and low efficiency, this paper presents a design scheme of intelligent addressable broadcast system which takes the advantages of Zigbee and frequency modulation (FM) technologies. This system adopts a cluster topology structure with a master and numerous of broadcast nodes. The network management and system control is realized by Zigbee. The audio signal is transmitted via FM broadcast. Besides, we realized the upper computer software design based on Visual C. The practical test shows that audio quality and system efficiency are both greatly enhanced, and the broadcast system is low-cost, low-power and low-complexity.

The current situation and the important role in power system of the time keeping system is described. It analyzed some questions which has been met in the development of the time keeping system and designed a time keeping system by GPS or Beidou as time mark.The double constant temperature trough crystal oscillator MV180 was used as the input clock of system, and used SCM control DAC7512 to adjust its frequency. The system carries on the frequency division processing to the adjusted local clock signal, then compares with the standard second signal received by the GPS or Beidou, adjusts the phase of the signal through frequency division by using FPGA and SCM, and finally, outputs the standard second pulse. It also can maintain the signal invariably after GPS or Beidou lock-lose to achieve the time synchronization of power system.

This paper proposes a novel method called arithmetic operations to analyze and process the generated voltage-signal from the single pair-pole magnetic encoder. Dual orthogonal voltage-signals are generated by two vertical hall sensors which are placed in the bottom of a columned magnet. When signals pass A/D converter, the quadrant determination, arithmetic operations and nonlinear correction in FPGA chip are performed before the values of rotational angle are displayed on the LED. This paper also designs and implements the single pair-pole magnetic encoder which has advantages such as high-speed, high-resolution and high-accuracy in the area of angle measurement.