Three-level Static Synchronous Compensator Research Articles

Mathematical Modeling and Simulation of Three-level STATCOM Based on Instantaneous Reactive Power Theory

Establishing an accurate static synchronous compensator (STATCOM) mathematical model is very important to the research of device performance, the design of main circuit parameters and control systems. The working principle of STATCOM and its multiple optimization technology are analyzed in this article, mathematical modeling of STATCOM is derived using the switch function method, and the stability of the model is analyzed using the Routh–Hurwitz stability criterion. Based on the traditional PI control of reactive current and instantaneous reactive power theory, a new control strategy is proposed by combining the inverse system method and sliding mode variable structure theory. The simulation research in MATLAB shows that the proposed model and control strategy can accurately and quickly reflect the transient process of STATCOM, it has obvious role for the ability to stabilize the bus voltage, and it can fast suppression load low-frequency fluctuations and voltage flicker.

三电平STATCOM新型直接功率控制策略研究

三电平静止同步补偿器(STATCOM)在配电网无功补偿领域发挥重要的作用。在三电平STATCOM控制策略中，传统的滞环式直接功率控制策略具有开关频率不固定的缺陷，这为网侧滤波器的设计带来了困难。本文提出一种新型三电平STATCOM定频直接功率控制策略。该策略从三电平STATCOM数学模型出发，以三电平SVPWM策略作为调制策略，采用以PI控制器为核心的前馈解耦控制系统对瞬时功率进行控制，以直流总电压的平方项为外环控制目标，在实现系统开关频率固定的同时得到良好的无功补偿效果。最后通过仿真验证了本文提出方法的正确性和合理性。 The three-level STATCOM (static synchronous compensator) plays an important role in the reactive power compensation of the distribution system. In all of the control strategies of three-level STATCOM, traditional hysteresis direct power control (DPC) strategy has the characteristics of uncertain switching frequency which made the grid connected filter hard to design. In this paper, it presents a novel constant switching frequency direct power control strategy of three-level STATCOM. The novel strategy based on the mathematical model of three-level STATCOM, and three-level SVPWM strategy is used as modulation strategy. Using PI controller and instantaneous power feedforward and decoupling control, the novel strategy realizes constant switching frequency as while as good reactive compensation effect. Finally, the simulation verified the correctness and rationality of the proposed method.

Three-Level 48-Pulse STATCOM with Pulse Width Modulation

In this paper, a new control strategy of a three-level 48-pulse static synchronous compensator (STATCOM) is proposed with a constant dc link voltage and pulse width modulation at fundamental frequency switching. The proposed STATCOM is realized using eight units of three-level voltage source converters (VSCs) to form a three-level 48-pulse STATCOM. The conduction angle of each three-level VSC is modulated to control the ac converter output voltage, which controls the reactive power of the STATCOM. A fuzzy logic controller is used to control the STATCOM. The dynamic performance of the STATCOM is studied for the control of the reference reactive power, the reference terminal voltage and under the switching of inductive and capacitive loads.

Three-level 24-pulse STATCOM with optimised magnetics to regulate voltage in transmission system

In this paper, a 24-pulse three-level ±100 MVAR STATCOM (static synchronous compensator) is evolved employing 4 × 6-pulse NPC GTO-VSCs (neutral point diode clamped gate-turn-off thyristor based voltage source converters) with magnetics optimised to a single stage. Through an angle control, the magnitude and phase angle of the STATCOM voltage is controlled with a pre-calculated dead angle in d-q synchronously rotating frame. While the performance of STATCOM is simulated in MATLAB platform for the voltage control in transmission system, its operating characteristics in respect of system dynamics and harmonics distortion are observed analogous to that of a conventional 48-pulse STATCOM. It has emerged to be cost effective topology of STATCOM.

Selection of passive elements for a three-level inverter based static synchronous compensator

Mathematical models for a three phase three-level static synchronous compensator (STATCOM) working with both fundamental frequency modulation and selective harmonic elimination modulation are described. The mathematical models were obtained by assuming that the power system and the operation of the STATCOM are on a balanced three-phase basis. The mathematical models were simplified to obtain the STATCOM AC side current, the DC capacitor voltage and the ripple for both switching strategies. These simplified design tools were validated using the exact model. The resonance between the DC side capacitance and the coupling reactance was studied using the mathematical model and the resonance frequency for the three-level STATCOM was obtained. The resonance frequency was validated against results of electromagnetic computer simulations. Using the design tools developed and considering the resonance studies, the process for selection of the size of DC side capacitors for a small STATCOM was demonstrated.