Smart grid and transparent grid require research and development of smarter, smaller, easier to install and cheaper power system sensors. The discovery of magnetoresistance effect and the development of its devices provide a new technical means for current measurement in power system, and can greatly reduce the volume of current sensor. On the basis of combing and comparing several current measurement technologies of power system, three design technical routes of current sensors based on tunnel magnetoresistance are proposed. The technical principles of two stickable micro current sensors are proposed and deduced, and the advantages, disadvantages and application scope of the measurement principle are analyzed. Aiming at different current measurement scenarios in power system, the development and research direction of micro current measurement technology based on tunneling magnetoresistance are pointed out.

Phasor mearsurement unit (PMU) for distribution network is a new generation of distribution network automation terminal, which has the characteristics of rapidity, accuracy, reliability and expansibility. During the popularization and application process, it is urgent to solve the problems in installation, cost, precision of current sensor and limitation of broadband. In this paper, an ultra-fast synchronous phasor measurement method based on magnetoresistance effect is proposed. Current is calculated by a two-axis magnetic sensor chip and a single-axis magnetic sensor chip. With the obtained current signal, a half-wave time-frequency domain algorithm based on improved wavelet transform is proposed to calculate the synchronous phasor. In order to improve the computational efficiency and reliability of the algorithm, the step signal is recognized by improved wavelet transform. At the same time, a calibration is employed to shift between half-wave time domain algorithm and frequency domain algorithm. In order to further verify the effectiveness of the proposed algorithm, simulation tests are carried out on the simulation software. The results verify the effectiveness of the proposed algorithm.

With the introduction of phasor measurement unit (PMU), measurable, observable and controllable level of distribution network can be greatly improved. Enormous challenges caused by the penetration of large-scale distributed generation and flexible load in post-modern distribution network can be solved. Distribution network can be promoted. In this paper, an adaptive phasor algorithm based on multi-self-calibration and multi-switching is proposed. Three modes of steady state, dynamic state and transient state are identified using multi-self-calibration, and algorithms adapting to three states are designed. In order to satisfy the requirements brought by the characteristics of PMU, this paper proposes a multi-self-switching method, which includes calibration algorithm, sensor type, sampling rate, window function type, data window length and synchrophasor algorithm. In order to further verify the superiority of the proposed algorithm, simulation analysis is carried out on simulation software. The results show that the proposed algorithm can meet the practical application requirements.

With the continuous development of measurement technology, the distribution phasor measurement unit (D-PMU) has gradually matured and been applied. Reasonable configuration is of great significance for the operation monitoring of distribution network and the large-scale promotion of D-PMU. Firstly, one-shot optimal configuration method of D-PMU which meets system completely observability is presented, and the staged optimal configuration methods and planning schemes considering the measurement redundancy and unobservable depth are also provided in the paper. Secondly, considering different application scenarios, the system architecture, data flow diagram and specific module design flow chart of optimal D-PMU configuration assistant decision-making software system adapted to multi-type optimal configuration requirements are proposed, and the platform of optimal D-PMU configuration assistant decision-making for distribution network is constructed. Finally, based on a real distribution network in Guangdong, the application analysis is carried out to verify the effectiveness of the proposed method.

The communication network and signal synchronization technology play a vital role in the development of intelligent distribution network. At present, the distribution network is large in scale, complex in structure and large in number of terminals. The existing technical means can no longer meet the demand of full coverage of communication and accurate synchronization of signals in distribution network. Aiming at the weak communication environment of distribution network, this paper proposes a wide area communication and synchronization scheme for distribution network based on the wireless industrial automation (WIA). The architecture of communication network and synchronization system is introduced in detail in this paper. The experimental results show that the combination of WIA technology and existing power communication resources can effectively solve the problems of acquisition blind spot and insufficient network coverage, and it can provide precise synchronization means for distribution network measurement system.

Compared with the safe private network transmission environment for the PMU data of the main network, the transmission of the D-PMU data of the distribution network with wired + wireless communication is vulnerable to cyber attackers. This paper analyzes the characteristics of D-PMU data and reveals the principle of network attack against D-PMU data. To enhance the security of data transmission, the paper proposes a data transmission network based on cognitive radio technology and a continuous encryption algorithm for adjacent device. Simulation results verify the correctness of the proposed methods.

The data collected by the new measurement devices, such as distribution network phasor measurement unit (D-PMU) and advanced metering infrastructure (AMI), together with the data collected by the traditional distribution network SCADA system, have become the data sources of the smart distribution network wide area measurement and control system (D-WAMCS). To make up for the disunity defect of modeling standards followed by each system during construction and to realize the exchange of data between each system, this paper first analyzes the hybrid measurement architecture of smart distribution network, and compares the differences among D-PMU data, AMI data and SCADA data in data components, data accuracy, time-scale information, etc., then proposes a unified information model to unify the equipment description of both IEC 61850 standard and IEC 61968x301 (CIM) standard. The proposed model is verified by the actual system in the demonstration area.

With the large number of distributed power sources connected to the grid, the voltage over-limit and stability problems of the distribution network are more serious, and the emergence of distribution network phasor measurement unit(D-PMU) provides a new means for real-time online monitoring of the stable operation of the distribution network. This paper proposes an online evaluation index for voltage quality that is suitable for D-PMU and comprehensively reflects the voltage stability and over-limit of the distribution network. Firstly, on the basis of analyzing the adaptability of the on-line voltage stability index in distribution network, it shows that the existing indexs can reflect the voltage stability of the distribution network to a certain extent, but it is difficult to reflect the common voltage out of bounds problem. Secondly, through constructing a continuous step simulation function to simulate the voltage out of bounds, an online evaluation index is proposed. The index can be quickly calculated by the measurement information of the D-PMU, which can well reflect the common voltage over-limit problem in the distribution network. Finally, the simulation is verified by a simple four-node power distribution system and an actual 20 kV distribution network model.The results show that the proposed index can reflect the voltage limit and stability of the distribution network timely, and verify the correctness and effectiveness of the index.

The distribution network has complex network structure, various types of equipment, and a wide range of operating points, while distribution automation equipment cannot achieve full coverage. This paper proposes a partial state estimation of distribution network method based on a nonlinear dynamical system approach. The proposed method is globally convergent and can use sparse synchronized phasor measurements without the traditional requirement of network observability. For the application of voltage control or thermal limit control, enhancing the accuracy of the voltage amplitude or the voltage phase angle is required. Under this situation, we propose an enhanced formulation including the voltage amplitude measurement residual constraints and voltage phase angle measurement residual constraints. The calculations cases show the effectiveness of the proposed method.

Flexible load adjustable interval prediction combines non-intrusive load identification and big data mining, big data mining obtains the probability characteristic curve of flexible load power, and then based on non-intrusive method to identify the actual opening period of flexible load in flexible load. The probabilistic characteristic curve of power intercepts the curve located in the time window of the period, and finally aggregates the multi-family households to obtain a flexible load-adjustable interval prediction utility model. Compared with the traditional method of installing the detection device, the non-intrusive identification pays more attention to the privacy of the user and also saves the cost of installing the device. Then, the relationship between the energy habits and the influencing factors is obtained by Apriori rule quantification, and finally the probability characteristic curve of the flexible load power of the resident users is obtained. Combining the two can obtain the flexible load adjustable interval prediction model.

At present, the hybrid on-load tap-changer for large-scale application utilizes the characteristics of the thyristor current zero-crossing of the power electronic device to suppress the arc generated during the switching operation, thereby improving the service life of the transformer. In this paper, the thyristor conduction current is obtained by simulating and experimentally analyzing the arc voltage formed by the floating potential of the gate contact, and the transient process of current and voltage during the turn-on and turn-off. This study provides a reference for the selection of thyristors for hybrid on-load tap-changers to improve the performance and reliability of on-load tap-changers.

There are a lot of redundancy and incompleteness in the alarm information of distribution network after fault, so it is important to extract the key fault information and get accurate diagnosis results through fault diagnosis in time for assisting the supervisor in dispatching work. Compared with the telemetry information only based on supervisory control and data acquisition (SCADA) system, wide area measurement system (WAMS) provides a unified time scale benchmark for fault alarm timing information by using the whole network synchronous clock, which brings new opportunities for fault diagnosis of distribution network. In this context, based on the sequence of event (SOE) information of synchronous time series, a fault diagnosis method for distribution network based on synchronized time series information characteristics of relay protection is proposed in this paper. Firstly, the stage timing coordination relationship in the relay protection system of distribution network is analyzed, and the time sequence relationship model of synchronous SOE information is established. Then, according to the characteristics of distribution network lines, the decision table method in rough set is improved, and the fault diagnosis rules with better generalization ability and practicability are obtained. Finally, the simulations of electromagnetic transient and diagnostic method are carried out on PSCAD platform, and the accuracy and validity of the diagnostic method are verified by the numerical results.

In view of the fact that there lacks fault phase selector and line parameters are inaccurate in medium voltage distribution network, a two-terminal fault location method based on parameter identification is proposed. Based on pre-fault PMU recording data, the method identifies the coupling parameters of the line through the voltage equation of the characteristic loop with coupling parameters. On this basis, the corresponding fault distance percentage for each phase is calculated respectively by least square principle using the recorded data of fault transient process of three-phase synthetically. The weighting coefficients are constructed by the signal energy of current fault components, and the percentage of fault distances of three phases is fused to determine the fault location according to the percentage of fault distances processed by fusion. The method can locate the fault point without the accurate parameters of the measured line and the phase selector. The simulation results of an example verify the effectiveness of the method.

Aiming at the roof photovoltaic of the industrial park and the electric vehicles in the residential area of the park, the vehicle-to-grid (V2G) technology of the electric vehicle and the time-of-use electricity price are taken into account, taking the minimum daily operating cost of the industrial park as objective, the photovoltaic and electric vehicles are scheduled cooperatively. Three scenarios are established and solved, which includes having no photovoltaic and no electric vehicle access to the industrial park, having photovoltaic and electric vehicle access and a disorder charging, and having photovoltaic and electric vehicle access and a order charging and discharging, respectively. The results of a calculation case show that the peak load of the park is decreased and the daily operating cost of the industrial park is also reduced in the scene of having photovoltaic and electric vehicle access and an orderly charging and discharging in the industrial park.

With a large amount of distributed energy accessing to the distribution network, the randomness of power fluctuations has a serious impact on the new energy consumption and equipment utilization. In this paper, the adjustable characteristics of the load side power are fully utilized, by adjusting the feeder voltage, the distributed energy output can be tracked by the load, thereby the suppression of the power at the point of common coupling (PCC) is achieved. In order to ensure the smooth suppression of fluctuations on the basis of economic operation of distribution network and to eliminate the influence of randomness of distributed energy on control, this paper establishes a source-load tracking model based on a framework of intraday optimization and real-time control. At the intraday optimization level, the optimization model is established with the adjacent period PCC power difference and operation cost as the objective function to solve the optimal PCC power. At the real-time control level, the voltage regulation is solved by rolling optimization based on the model predictive control algorithm and the results of the intraday optimization, so as to realize the source-load tracking. Finally, a case of the measured data from an industrial park in Guangzhou verifies the effectiveness of the model in suppressing the power fluctuation.

In order to solve the voltage violation in distribution network caused by the access of distributed photovoltaic, the state of the photovoltaic-containing distribution network is estimated online based on the distribution phasor measurement unit (DPMU) measurement information. Then, the voltage optimal control gradient is extracted online through sensitivity analysis. According to the MPC theory, a voltage control model is established to coordinate various voltage regulating devices including static var compensor (SVC) and photovoltaic inverter in a wide-area range. Considering the cooperation between real-time voltage control and action of discrete capacitor, a closed-loop control strategy of feeder voltage is proposed. The simulation analysis of the IEEE 33-bus example is carried out to verify the effectiveness and rapidity of the proposed real-time voltage control strategy.