scholarly journals Research on Control Method of Neutral Point Potential Balance of T-Type Three-level Inverter Based on PLECS

2021 ◽  
Vol 2087 (1) ◽  
pp. 012051
Author(s):  
ZhuoQun Liu ◽  
JunChi Ma ◽  
KaiXu Liu
Keyword(s):  
Electromagnetic Interference ◽  
High Efficiency ◽  
Reactive Power ◽  
Control Method ◽  
Balance Control ◽  
Neutral Point ◽  
Voltage Source ◽  
Point Potential ◽  
Capacitor Voltage ◽  
Inverter Topology

Abstract The T-type three-level inverter topology has the advantages of low electromagnetic interference, high efficiency, and low output harmonic content. This article combines constant power inverter, independent control of active and reactive power output, Analyzed and studied the neutral point potential balance control of the T-type three-level inverter topology. Through PI adjustment control on the amount of charge of the capacitor, the midpoint voltage of the capacitor is always maintained in a balanced state, and the fluctuation of the midpoint voltage is controlled within ±0.23%. This method can effectively avoid the influence of the difference of capacitance parameters on the DC side on the midpoint voltage. The PLECS software simulation verifies the reliability of the capacitor voltage equalization circuit under the condition of the voltage imbalance at the midpoint of the DC side voltage source supply capacitor voltage equalization.

scholarly journals Analysis of Three Phase 3-Level NPC Voltage Source Converter for AC-DC Conversion

2020 ◽  
Vol 06 (09) ◽  
pp. 144-148
Author(s):  
A Divya Teja and Dr. N Sambasiva Rao
Keyword(s):  
Power Quality ◽  
Power Flow ◽  
Reactive Power ◽  
Neutral Point ◽  
Voltage Source ◽  
Voltage Source Converter ◽  
Phase 3 ◽  
Control Techniques ◽  
Point Potential ◽  
Three Phase

The use of power electronic converters influences the generation of harmonics and reactive power flow in power system. Therefore, three-phase multilevel improved power quality AC-DC converters are gaining lot of popularity in power conversion applications. This work deals with critical problem of multilevel structure i.e neutral point potential (NPP) variation. In this paper, a simplified current controlled scheme is presented to ensure unity power factor operation. Neutral point potential (NPP) of three-phase, 3-level NPC AC-DC converter is controlled by modifying control signal in the controller using NPP regulator. An auxiliary circuit is being presented in this paper as an alternative option for controlling the neutral point potential of the converter. Comparison has been carried out between these control techniques in terms of power quality. A complete mathematical model is presented for better understanding of both techniques used for NPP control. The presented control techniques has been verified through simulation investigations and validated

scholarly journals Research on SVPWM Method and its Neutral Point Potential Control

2011 ◽  
Vol 2-3 ◽  
pp. 39-42
Author(s):  
Yan Liu ◽  
Xu Wang ◽  
Yan Xing
Keyword(s):  
Passive Control ◽  
Balance Control ◽  
Neutral Point ◽  
Superior Performance ◽  
Voltage Source ◽  
Effective Control ◽  
Potential Control ◽  
Point Potential ◽  
Voltage Vector ◽  
Three Phase

Neutral-point potential unbalance is an inherent problem of Neutral-point-clamped three-level PWM rectifiers. If the problem of neutral point can’t be controlled appropriately, the harm of input current will increase, and even the dc-link capacitor and switches will be destroyed. Thus domestic and foreign experts have done lots of research on the balance control of Neutral-point-clamed and put forward many effective control methods. This paper proposes a novel SVPWM strategy for the three-level neutral-point-clamped voltage source inverter, based on the particular disposition of all the redundant voltage vectors. The new modulation approach shows superior performance for the harmonic voltage and the control of neutral-point potential compared to the popular eight-stage centered SVPWM and realizes the balancing control of inverter neutral-point potential by modifying redundant small vectors pairs’ distribution factor accurately, only requiring the information of dc-link capacitor voltages and three-phase load currents, which is convenient to apply and is compatible of digital computer realization. The feasibility of the proposed control approach has been verified via simulation and experiment results. In the strategy of software control, domestic and foreign scholars propose numerous neutral point potential control schemes. When carrier modulation is used, the balance control is achieved by injecting zero-sequence component into the three-phase modulated wave. When space vector modulation methods are adopted, they can be divided into three categories: passive control, hysteresis control and active control. there is also a new algorithm based on the intrinsic relationship between SVPWMs for two—level inverters and three．1evel inverters．a novel SVPWM control algorithm is proposed for three．1evel．The dwell time of voltage vector for three-level inverter can be acquired from counterpart for two-level inverter by using a linear transformation．Aiming to analysis the output PWM sequence of three-level inverter, a novel classification standard of voltage vector is proposed．Based on evaluating the PWM sequences, a novel PWM sequence is given，that can reduce the total harmonics distortion of inverter output.

Research and Design for Cascade SVG Control System

2014 ◽  
Vol 543-547 ◽  
pp. 776-779
Author(s):  
Y.C. Zhang ◽  
Q. Yang ◽  
L.J. Huo ◽  
Y.F. Zhang ◽  
X. Hu ◽  
...  
Keyword(s):  
Reactive Power ◽  
Control Method ◽  
Balance Control ◽  
Dynamic Adjustment ◽  
Voltage Vector ◽  
Capacitor Voltage ◽  
Voltage Balance ◽  
Voltage Balance Control ◽  
Capacitor Voltage Balance ◽  
Research And Design

This paper researchs alternating current decoupling control and DC capacitor voltage balance control for cascade SVG. The DC capacitor voltage balance control method has advantages of good stability and wide regulation range which uses the active voltage vectors of each module. The active voltage vector only change the active power of each module without affecting the reactive power. Experimental results show that the system can accurately compensate the reactive load, and has good performance in the steady state and dynamic adjustment.

scholarly journals A Novel Adaptive Control Approach Based on Available Headroom of the VSC-HVDC for Enhancement of the AC Voltage Stability

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3222
Author(s):  
Duc Nguyen Huu
Keyword(s):  
Adaptive Control ◽  
Voltage Stability ◽  
Reactive Power ◽  
Control Method ◽  
Offshore Wind ◽  
Voltage Source ◽  
Long Distance ◽  
Control Approach ◽  
Hvdc System ◽  
Voltage Support

Increasing offshore wind farms are rapidly installed and planned. However, this will pose a bottle neck challenge for long-distance transmission as well as inherent variation of their generating power outputs to the existing AC grid. VSC-HVDC links could be an effective and flexible method for this issue. With the growing use of voltage source converter high-voltage direct current (VSC-HVDC) technology, the hybrid VSC-HVDC and AC system will be a next-generation transmission network. This paper analyzes the contribution of the multi VSC-HVDC system on the AC voltage stability of the hybrid system. A key contribution of this research is proposing a novel adaptive control approach of the VSC-HVDC as a so-called dynamic reactive power booster to enhance the voltage stability of the AC system. The core idea is that the novel control system is automatically providing a reactive current based on dynamic frequency of the AC system to maximal AC voltage support. Based on the analysis, an adaptive control method applied to the multi VSC-HVDC system is proposed to realize maximum capacity of VSC for reactive power according to the change of the system frequency during severe faults of the AC grid. A representative hybrid AC-DC network based on Germany is developed. Detailed modeling of the hybrid AC-DC network and its proposed control is derived in PSCAD software. PSCAD simulation results and analysis verify the effective performance of this novel adaptive control of VSC-HVDC for voltage support. Thanks to this control scheme, the hybrid AC-DC network can avoid circumstances that lead to voltage instability.

scholarly journals A Novel Neutral-Point Potential Balance Strategy for Three-Level NPC Back-to-Back Converter Based on the Neutral-Point Current Injection Model

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Yingjie Wang ◽  
Haiyuan Liu ◽  
Wenchao Wang ◽  
Kangan Wang
Keyword(s):  
Balance Control ◽  
Neutral Point ◽  
Control Algorithms ◽  
Model Based ◽  
Point Potential ◽  
Injection Model ◽  
Zero Sequence ◽  
Flow Through ◽  
Dc Bus ◽  
Zero Sequence Voltage

The neutral-point (NP) potential balance control in three-level neutral-point-clamped (NPC) back-to-back converter is a research nodus. Its current strategies are the same as the strategies of a single three-level NPC converter. But the strategies do not give full play to its advantages that the neutral-point current can only flow through the connected midlines in both sides of the converter but does not flow through the DC-bus capacitors. In this paper, firstly the NP potential model based on the NP current injected is proposed. It overcomes numerous variable constraints and mutual coupling in the conventional model based on the zero-sequence voltage injected. And then on this basis, three NP-potential balance control algorithms, unilateral control, bilateral independent control, and bilateral coordinated control, are proposed according to difference requirements. All of these algorithms use the midlines rather than the DC-bus capacitors to flow the NP current as much as possible. Their control abilities are further quantitatively analyzed and compared. Finally, simulation results verify the validity and effectiveness of these algorithms.

scholarly journals A new seven level boost-type ANPC inverter topology for photovoltaic applications

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jagabar Sathik M. ◽  
Dhafer J. Almakhles
Keyword(s):  
Power Loss ◽  
Output Voltage ◽  
Detailed Comparison ◽  
Input Voltage ◽  
Neutral Point ◽  
Type Structure ◽  
Photovoltaic Applications ◽  
Capacitor Voltage ◽  
Floating Capacitor ◽  
Inverter Topology

AbstractDeveloping of new photovoltaic inverter topologies is received more attention in the last few years. In particular, designing an active neutral-point-clamping inverter type structure is quite popular for PV applications. The output voltage is always half of the input voltage (vin), which further increases the voltage rating of dc-link capacitors in the conventional three-level ANPC. To rectify the above problem and increase the output voltage by reducing dc-link capacitors voltage rating, a new boost type seven-level ANPC inverter topology is proposed. The proposed topology consists of seven switches and one floating capacitor. The floating capacitor voltage is self-balanced, and the output voltage is 1.5 times higher than the input voltage. A detailed comparison for some power components, power loss and cost with other existing topologies are presented. Further, the proposed topology is validated in a prototype hardware setup for different load values.

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