Direct Power Flow Controller With A Range Of 360° Based On Bipolar Modulation

In order to improve the power transmission capacity of the power grid,the stability of the power system and the effectiveness of power flow control,on the premise of solving the continuous regulation of the amplitude and phase of the power grid voltage within 360°and requiring the circuit structure to be as simple as possible,bipolar modulation 360°direct power flow controller is proposed through the innovation of the circuit structure and combined with the vector synthesis technology.The circuit structure obtains the phase voltage and line voltage respectively through the input transformer group of the parallel power grid.According to the working principle of the circuit,the specific compensation voltage phase and amplitude are given and fed back to the power grid through the series transformer group,so as to realize the independent and continuous control of the phase and amplitude of the power grid voltage.And finally achieve the goal of flexible control of active power flow and reactive power flow in the power grid.Firstly,the topology of bipolar modulation 360° direct power flow controller is given,and its working principle is introduced in detail.By using the transformer group with center tap on the secondary side and the bipolar modulation 360° buck AC conversion unit,the compensation voltage of each phase of the power grid is continuously adjusted within the 360° rectangular range,which is connected in series into the power grid to obtain the voltage amplitude and phase that meet the requirements after compensation.At the same time,it also realizes the flexible control of active power flow and reactive power flow in the power grid alone or at the same time.Secondly,the circuit principle of bipolar modulation 360° direct power flow controller is simulated and verified by saber sketch system simulation software.The power grid,main circuit and control circuit model of bipolar modulation 360° direct power flow controller are designed.The correctness of the theoretical basis is verified by comparing the error between the actual value and preset value of voltage amplitude and phase measured after compensation.Then,taking one phase of the grid voltage as the reference,the amplitude and phase of the other two phases change within a certain range,and finally realize the three-phase imbalance of the input voltage.The corresponding voltage compensation is given through the theoretical calculation of the formula,which can still make the threephase balance of the compensated grid voltage.This section gives the relevant waveforms of the three-phase imbalance compensation experimental simulation.Then it involves the design of hardware circuit,mainly including driving signal synthesis circuit,driving circuit,main circuit,amplitude sampling and phase sampling circuit.TMS320F2812 DSP is used as the control core of the whole hardware circuit,which mainly involves the supply of the main chip voltage in the switch PWM control signal and drive signal synthesis circuit.This paper explains the design idea of circuit diagram in detail through image drawing,and gives the programming code based on C language in CCS platform.Finally,according to the theoretical basis proposed in this paper and the circuit diagrams of each part of the bipolar modulation 360° direct power flow controller,a principle prototype is developed,and the experimental data show that the bipolar modulation 360° direct power flow controller can continuously adjust the amplitude and phase of the grid voltage independently and flexibly in the 360° rectangular range.