CN102638039B

CN102638039B - Three-phase chain-type static synchronous compensator

Info

Publication number: CN102638039B
Application number: CN201210077064.2A
Authority: CN
Inventors: 姜齐荣; 杜威
Original assignee: ZHANGJIAGANG ZHIDAIN ELECTRIC POWER ELECTRONIC INSTITUTE Co Ltd; Tsinghua University
Current assignee: ZHANGJIAGANG ZHIDAIN ELECTRIC POWER ELECTRONIC INSTITUTE Co Ltd; Tsinghua University
Priority date: 2012-03-22
Filing date: 2012-03-22
Publication date: 2014-05-28
Anticipated expiration: 2032-03-22
Also published as: CN102638039A

Abstract

The invention relates to a three-phase chain-type static synchronous compensator and belongs to the technical field of flexible alternating current power transmission and distribution system and power electronics. The three-phase chain-type static synchronous compensator is characterized in that a plurality of groups of H-bridge inverter units are connected in series to form a first chain-type structure; the both ends of the first chain-type structure are respectively connected with a first filter inductor in series; three groups of same first chain-type structures, which are connected with filtering inductors in series, are connected with one another in a triangular way so as to form the three-phase chain-type static synchronous compensator in a triangularly connected way; a plurality of groups of H-bridge inverter units are connected in series to form a second chain-type structure; the three outlets of the three-phase chain-type static synchronous compensator in the triangularly connected way are respectively connected with one second chain-type structure in series; and the outlet of each second chain-type structure is connected with a breaker and a power grid in sequence through a second filtering inductor. The static synchronous compensator disclosed by the invention is capable of simultaneously compensating reactive power and negative-sequence current, has lower pressure resistance demand on devices, and utilizes the H-bridge inverter units as a modularized structure, and therefore, the static synchronous compensator is convenient for production, simple in structure and low in cost.

Description

A kind of three-phase chain static synchronous compensator

Technical field

The present invention relates to a kind of three-phase chain static synchronous compensator, belong to flexible AC electrical power trans mission/distribution system and electric and electronic technical field.

Background technology

In fields such as electric power system, steel-making, metallurgy, wind power generation, electric railways, reactive power compensation and imbalance compensation are just more and more subject to the attention of relevant department.Reactive power surplus will increase loss and the voltage-drop of circuit; reactive power fluctuation is also by the serious busbar voltage quality that affects frequently; electrical endurance light power consumption equipment around reducing; heavy make generator and power consumption equipment around protect action because voltage is defective, the accident such as cause power failure, factory cannot normally work.Therefore, power department has been set up strict standard to the examination of power factor, conventionally all require the power factor in electricity consumption place to reach more than 0.9, otherwise can impose a fine it, in the electricity consumption place of some reactive power frequent fluctuation, as electric railway and steel mill, often require it to adopt the dynamic reactive compensation device with capability of fast response to administer.In recent years, because exceeding standard, points of common connection negative sequence voltage degree of unbalance cause the accident of generator and load tripping operation also to be appeared in the newspapers repeatly, power department is also more and more paid attention to the examination to points of common connection negative sequence voltage degree of unbalance, each user that national standard " quality of power supply-imbalance of three-phase voltage " (GB/T15543-2008) requires to be connected to points of common connection causes that this point voltage negative phase-sequence degree of unbalance permissible value is generally 1.3%, must not exceed 2.6% in short-term, the power consumer exceeding standard for Voltage unbalance degree, require to adopt compensation equipment that degree of unbalance is compensated in acceptability limit.

In most electricity consumptions place, as electric railway, steel mill, metallurgy etc., power factor is not up to standard often to be existed with the negative phase-sequence degree of unbalance problem that exceeds standard simultaneously, need to administer simultaneously.In recent years, due to the fast development of flexible AC power transmission and distribution technology, the three-phase chain static synchronous compensator (hereinafter to be referred as STATCOM) based on H bridge inverter cellular construction is widely used in distribution system and carries out idle and dynamic compensation negative phase-sequence.Traditional chain type STATCOM mainly contains two kinds of topological structures, i.e. delta connection and star connection, as shown in Figure 1 and Figure 2.The STATCOM of star connection has feature simple in structure, cost is low, can be used for the dynamic passive compensation of distribution system, but the chain type STATCOM of star connection is when for negative sequence compensation, electric current and the voltage of three-phase all there are differences, control difficulty very large, the chain type STATCOM of star connection does not still possess the ability of compensation negative phase-sequence at present, the every link mutually of STATCOM of delta connection bears the line voltage of system, because the line voltage of system is three-phase symmetrical substantially, when compensating negative phase-sequence, only need the corresponding asymmetric electric current of control STATCOM generation can compensate preferably the negative-sequence current of distribution system, therefore the chain type STATCOM of dihedral connection has the ability of while compensating power and negative phase-sequence, there is at present the chain type STATCOM of more delta connection to be applied in the case of the next compensating reactive power simultaneously of industry spot and negative phase-sequence, but, what bear due to the every link mutually of the chain type STATCOM of delta connection is system line voltage, with respect to the star connection chain type STATCOM under identical electric pressure and capacity, voltage withstand class to each insulation gate pole bipolar transistor (hereinafter to be referred as IGBT) device is had relatively high expectations, or the more H bridge unit of must connecting reaches same withstand voltage level, thereby make the chain type STATCOM cost of dihedral connection far above the chain type STATCOM of star connection.

Summary of the invention

The object of the invention is to propose a kind of three-phase chain type synchronous static compensator, the deficiency existing separately to make up star connection and dihedral connection, in adopting the relatively low IGBT of withstand voltage rank, make it have again the ability of good compensation negative phase-sequence, thereby reduce the cost of equipment.

The three-phase chain static synchronous compensator that the present invention proposes, its structure is: will organize H bridge inverter units in series more, form the first chain structure, at first filter inductance of the each series connection in the two ends of the first chain structure, there is the first chain structure of filter inductance to connect by triangle manner three groups of identical strings, form the three-phase chain static synchronous compensator of a delta connection; To organize H bridge inverter units in series more, form the second chain structure, in second chain structure of three each series connection of outlet of the three-phase chain static synchronous compensator of described delta connection, the outlet of each the second chain structure is connected with electrical network with a circuit breaker by the second filter inductance successively.

The three-phase chain static synchronous compensator that the present invention proposes, its advantage is: with respect to the chain type STATCOM of existing star connection, because the inside of three-phase chain static synchronous compensator of the present invention has the part that triangle connects, therefore compared with the STATCOM of STATCOM of the present invention and existing star connection, there is the ability of good compensation negative phase-sequence; With respect to the chain type STATCOM of existing delta connection, because three-phase chain static synchronous compensator of the present invention accesses electrical network after some groups of H bridge cellular constructions of the each series connection of outlet of each end points of the chain type STATCOM of delta connection, therefore can adopt the relatively low IGBT of withstand voltage rank.Therefore, three-phase chain static synchronous compensator of the present invention, has possessed the ability of compensating power and negative-sequence current simultaneously, and lower to the requirement of withstand voltage of device, the H bridge inversion unit of employing is modular construction, is convenient to produce, simple in structure, with low cost.

Accompanying drawing explanation

Fig. 1 is the structural representation of the three-phase chain static synchronous compensator of existing star connection.

Fig. 2 is the structural representation of the three-phase chain static synchronous compensator of existing delta connection.

Fig. 3 is the structural representation of the three-phase chain static synchronous compensator that proposes of the present invention.

Fig. 4 is the structural representation of H bridge unit inverter in three-phase chain static synchronous compensator.

Embodiment

The three-phase chain static synchronous compensator that the present invention proposes, its structure as shown in Figure 3, for: will organize H bridge inverter units in series more, form the first chain structure, at first filter inductance of the each series connection in the two ends of the first chain structure, there is the first chain structure of filter inductance to connect by triangle manner three groups of identical strings, form the three-phase chain static synchronous compensator of a delta connection; To organize H bridge inverter units in series more, form the second chain structure, in second chain structure of three each series connection of outlet of the three-phase chain static synchronous compensator of described delta connection, the outlet of each the second chain structure is connected with electrical network with a circuit breaker by second filter inductance successively.

In three-phase chain static synchronous compensator of the present invention, triangle connects the inner H bridge module being often in series and counts H bridge module that h and Angle connection outside be often in series and count j and can set flexibly according to line voltage grade, compensation ability to negative phase-sequence.

As shown in Figure 3, three-phase chain static synchronous compensator of the present invention, by basic unit cascaded the forming of H bridge inverter, first becomes the first chain structure by h H bridge inverter units in series, and the filter inductance L that respectively connects at these chain structure two ends ₁there is the chain structure of filter inductance to connect by triangle manner three groups of identical strings, form the three-phase chain static synchronous compensator of a delta connection, in its three outlets leading-out terminal x, y, z respectively, second chain structure being formed by j H bridge inverter units in series of each series connection at each terminal place, each the second chain structure is successively by the second filter inductance L ₂with circuit breaker Q access three-phase electrical power system.The numerical value of h and j can arrange flexibly according to electric pressure and the compensation ability to negative phase-sequence.See from grid side the three-phase chain static synchronous compensator that the present invention proposes, be similar to the chain type STATCOM of star connection, just its neutral point is extended for to the chain type STATCOM of an Angle connection; See to electrical network from device side, be similar to the chain type STATCOM of dihedral connection, just in the outlet of the every phase chain structure being formed by multiple H bridge inverter units in series of having connected again.

The three-phase chain static synchronous compensator that the present invention proposes, the structure of H bridge inverter unit wherein comprises two brachium pontis, wherein each brachium pontis forms by upper and lower two insulation gate pole bipolar transistors (IGBT) and with the diode of upper and lower two insulation gate pole bipolar transistor reverse parallel connections respectively, and at electric capacity of DC side parallel and discharge resistance, the mid point of each brachium pontis is drawn a terminal.As shown in Figure 4, H bridge inverter unit comprises two brachium pontis, wherein left brachium pontis is by upper and lower two IGBT (S1 and S2) and form with diode D1, the D2 of S1 and S2 reverse parallel connection respectively, and right brachium pontis is by upper and lower two IGBT (S3 and S4) and form with diode D3, the D4 of S3 and S4 reverse parallel connection respectively.And at capacitor C of DC side parallel and discharge resistance R, the mid point leading-out terminal a of left brachium pontis, the mid point leading-out terminal b of right brachium pontis.The operation principle of H bridge inverter unit is: suppose when the voltage of DC side after H bridge capacitor charging be E.When IGBT1 conducting, when IGBT2 turn-offs, a terminal is E with respect to the voltage of electric capacity negative pole, and when IGBT1 turn-offs, when IGBT2 conducting, a terminal is 0 with respect to the voltage of electric capacity negative pole; When IGBT3 conducting, when IGBT4 turn-offs, b terminal is E with respect to the voltage of electric capacity negative pole, and when IGBT3 turn-offs, when IGBT4 conducting, b terminal is 0 with respect to the voltage of electric capacity negative pole.Therefore, the voltage difference between a, b terminal can have altogether 3 kinds of level ,+E ,-E, 0.

Claims

1. a three-phase chain static synchronous compensator, the structure that it is characterized in that this STATCOM is: will organize H bridge inverter units in series more, form the first chain structure, at first filter inductance of the each series connection in the two ends of the first chain structure, there is the first chain structure of the first filter inductance to connect by triangle manner three groups of identical strings, form the three-phase chain static synchronous compensator of a delta connection; To organize H bridge inverter units in series more, form the second chain structure, in second chain structure of three each series connection of outlet of the three-phase chain static synchronous compensator of described delta connection, the outlet of each the second chain structure is connected with electrical network with a circuit breaker by the second filter inductance successively.