A kind of constant-speed and constant-frequency wind-powered electricity generation unit low-voltage traversing device and control method
Technical field:
The present invention relates to field of power, be specifically related to a kind of constant-speed and constant-frequency wind-powered electricity generation unit low-voltage traversing device and control method.
Background technology:
Along with the fast development of wind generating technology and countries in the world on policy to the attention of renewable energy power generation, wind power generation has got into the fast-developing phase.Wind-powered electricity generation unit single-machine capacity, wind energy turbine set scale and wind power generation shared share in electric power system all increases gradually.Planning, construction, traffic control, analysis and Control, economical operation and the quality of power supply that large-scale wind power generation is connected to the grid to electrical network have all produced certain influence.In order to promote the orderly exploitation of wind energy turbine set; Guarantee the safe and stable operation of electric power system; Some the electric power associations or the grid company in areas such as Europe, North America, Australia have all been formulated wind farm grid-connected technological guide rule, and China has issued in 2006 that also relevant national standard and State Grid Corporation of China's wind energy turbine set insert the power system technology regulation.The wind farm grid-connected technical stipulation of various countries relates to some common problems; Comprise power control, reactive power, low voltage ride-through capability etc.; Wind-powered electricity generation set grid-connection technology has been proposed specific requirement; Wherein to possess low voltage ride-through capability be the huge challenge to wind-powered electricity generation set grid-connection technology to the wind-powered electricity generation unit, therefore presses for a kind of device and solve the problem that exists in the wind-electricity integration technical field at present.
At present; Low-voltage traversing device to the asynchronous wind-powered electricity generation unit of constant-speed and constant-frequency is also fewer; There have some scholars to propose to be a kind of based on dynamic electric voltage recovery device (Dynamic Voltage Restorer, DVR) the asynchronous wind-powered electricity generation unit of the constant-speed and constant-frequency of principle low-voltage traversing device.Shown in accompanying drawing 1; Between wind-powered electricity generation unit and network system, connect and insert a cover DVR device; This device mainly comprises with lower module: module 1 is charge circuit AC power (or not being equipped with this part); Module 2 is DVR H bridge converters back-to-back, and module 3 is discharge IGBT buffering absorption circuits, and module 4 is DVR output low pass filters.When the wind-powered electricity generation unit normally is incorporated into the power networks; Two last brachium pontis IGBT normal opens or two following brachium pontis IGBT normal opens through control module 2 the insides form alternating current path with fly-wheel diode; Make converter export no-voltage; Network system and wind-powered electricity generation unit directly exchange meritorious and idle through switching device, other parts are not participated in work.In case the network system voltage dip takes place, and the operating state of DVR changes at once, full remuneration network system electric voltage dropping value realizes that just wind-powered electricity generation unit set end voltage is constant, still maintains normal working voltage.So can not make wind-powered electricity generation unit under-voltage protection action, thereby realize that successfully low-voltage passes through.In this scheme; Be not difficult to find by electric current and Voltage Reference direction; The active power that the whole wind group of motors is sent when the network system fault has very that major part has all flowed into the DVR loop, thereby causes the rising of DVR direct voltage, needs discharge to the converter DC bus-bar voltage through appropriate control; Usually adopt pulse width modulation mode (PWM) control discharge IGBT to realize that finally these active power are through the discharge resistance consumption parallelly connected with capacitor.After the network system fault recovery, the DVR device stops the bucking voltage operating state, continues to operate in the alternating current path pattern that IGBT and fly-wheel diode constituted in the module 2.Workflow realization wind-powered electricity generation unit low-voltage through such is passed through.
This scheme based on DVR has more shortcoming.The first, the normal operating conditions power electronic device will be operated under the wind-powered electricity generation unit output-current rating all the time, and the requirement on devices to IGBT is very high like this, and cost can raise suddenly, and this shortcoming be this series connection DVR scheme can't overcome; The second, only on the power electronic device number that is suitable for, be not difficult also to find that the controlling schemes of this DVR uses full control device IGBT more, this will inevitably cause the complicacy of control system and the raising of installation cost; The 3rd; This control mode needs converter to set up the galvanic current pressure; And the foundation of converter direct voltage needs an independently DC charging loop or when network system breaks down, rely on gaining merit that the wind-powered electricity generation unit sends to set up; The former can increase the cost and the floor space of this covering device greatly, and the latter then can make control complicated, and both need suppress overvoltage through discharge loop at the wind-powered electricity generation unit again when the feed-in of DVR device is meritorious; Keep dc voltage stability, so the difficulty of DC voltage-stabilizing control increases again to some extent.More than this some explained that all the low-voltage traversing device based on the DVR principle exists more deficiency and shortcoming at aspects such as installation cost, control complexity, engineered enforcement difficulty.
Summary of the invention:
Deficiency to prior art; The present invention provides a kind of constant-speed and constant-frequency wind-powered electricity generation unit low-voltage traversing device and control method; Can guarantee normally being incorporated into the power networks of network system stable situation leeward group of motors; The specification requirement of wind energy turbine set, wind-powered electricity generation set grid-connection is satisfied in the recovery that the meritorious trend of the quick consumption of wind energy and fault recovery after wind group of motors is carried during the network system voltage dip.
A kind of constant-speed and constant-frequency wind-powered electricity generation unit low-voltage traversing device provided by the invention, its improvements are that series connection inserts switch between network system and wind-powered electricity generation unit; Parallel connection inserts the contactor and the reactive compensation module of series connection between said switch and wind-powered electricity generation unit; Parallel connection inserts meritorious absorption circuit between said contactor and reactive compensation module; Said switch is an electronic switch.
Wherein, said switch is used for when the voltage dip fault appears in network system, cutting off the wind-powered electricity generation unit to the meritorious passage of network system feed-in, and after network system voltage recovers, fast the wind-powered electricity generation unit is communicated with network system.
The reactive power of needs when wherein, said reactive compensation module is used to compensate the wind-powered electricity generation unit and normally moves.
Wherein, said meritorious absorption circuit is used for absorbing after voltage dip fault, the disconnection of said switch appear in network system, the active power that the wind-powered electricity generation unit sends.
Wherein, parallel connection inserts lightning arrester between said contactor and said reactive compensation module.
Wherein, said electronic switch comprises anti-parallel thyristor or inverse parallel GTO.
Wherein, said network system voltage dip fault is meant when the phenomenon of the arbitrary phase voltage of network system three-phase voltage during less than V1 and is called network system voltage dip fault; Network system voltage recovers to be meant when the network system three-phase voltage returns to amplitude V2, thinks that network system voltage recovers.
Wherein, said reactive compensation module comprises Shunt Capacitor Unit.
Wherein, said meritorious absorption circuit comprises reactor, the uncontrollable rectifier bridge of three-phase and discharge circuit; It is parallelly connected after said reactor is connected with the uncontrollable rectifier bridge of said three-phase with said discharge circuit.
Wherein, said meritorious absorption circuit comprises that reactor, discharge resistance, the uncontrollable rectifier bridge of three-phase, discharge IGBT and IGBT buffering absorb circuit; Said reactor is connected with said discharge resistance and the uncontrollable rectifier bridge of said three-phase successively, and the uncontrollable rectifier bridge of said three-phase is parallelly connected with said discharge IGBT; Said discharge IGBT is parallelly connected with said IGBT buffering absorption circuit.
Wherein, said discharge circuit comprises that discharge resistance, discharge IGBT, IGBT buffering absorb circuit and fly-wheel diode; Connect with said discharge IGBT after said discharge resistance and the said fly-wheel diode parallel connection; Said discharge IGBT is parallelly connected with said IGBT buffering absorption circuit.
Wherein, said IGBT buffering absorption circuit comprises resistance, electric capacity and diode; Said resistance and capacitances in series, said diode is parallelly connected with said resistance.
The present invention is based on a kind of control method like above-mentioned low-voltage traversing device that another purpose provides, its improvements are that said method comprises the steps:
(1) said contactor is closed;
(2) judge whether network system the voltage dip fault occurs, if do not break down, then closed said switch is communicated with between network system and the wind-powered electricity generation unit; If the voltage dip fault occurs, carry out step (3);
(3) break off said switch, the conducting of controller control discharge IGBT, meritorious absorption circuit absorbs the active power that the wind-powered electricity generation unit sends; The reactive power that reactive compensation module compensation wind-powered electricity generation unit needs when normally moving; Recover if detect the network system three-phase voltage, carry out step (4);
(4) closed said switch, the locking discharge IGBT is forbidden meritorious absorption circuit work, recovers the energy exchange passage between wind-powered electricity generation unit and the network system.With the prior art ratio, beneficial effect of the present invention is:
The present invention has avoided the frequent switching of wind-powered electricity generation unit.
The used full control device of the present invention is less, and cost is lower.
Control system of the present invention is simple and easy to realize.
When the present invention works, do not need independently to add charge power supply.
Apparatus of the present invention are taken up an area of very little, are no more than the position of a screen cabinet usually, are beneficial to the transformation to existing unit.
The used power electronic device cost of device of the present invention is low, has reduced the comprehensive cost of the complete sets of equipment, takes into account economy and practicality, has application promise in clinical practice.
Whether contactor control lightning arrester of the present invention, reactive compensation module and the meritorious circuit that absorbs are put in the whole system; If lightning arrester, reactive compensation module and the meritorious circuit that absorbs break down; Can this part be logged off through breaking off contactor, strengthen the fail safe of system.
The present invention installs after low-voltage passes through the comprehensive regulation device, has played and has suppressed the influence that the network system voltage dip brings for the wind-powered electricity generation unit.Strengthen the power supply reliability of wind-powered electricity generation factory simultaneously, the blower fan that more can reduce in the same wind-powered electricity generation unit is compelled the situation of complete resection owing to the network system voltage dip, has very strong practicality, with bringing very big economic benefit.
Description of drawings
Fig. 1 is a kind of low-voltage traversing device based on DVR
Fig. 2 is a low-voltage traversing device structure chart one provided by the invention
Fig. 3 is a low-voltage traversing device structure chart two provided by the invention
Fig. 4 is a low-voltage traversing device structure chart three provided by the invention
Fig. 5 is provided by the invention to low-voltage traversing device control flow chart.
Among the figure of the present invention, 1 is switch, and 2 are the meritorious circuit that absorbs, and 3 is reactive compensation module, and 4 is lightning arrester, and 5 is the wind-powered electricity generation unit.
Embodiment
Do further to specify below in conjunction with the accompanying drawing specific embodiments of the invention.
Embodiment one
As shown in Figure 2, the low-voltage traversing device of present embodiment is that series connection inserts switch between network system and wind-powered electricity generation unit; Parallel connection inserts the contactor and the reactive compensation module of series connection between said switch and wind-powered electricity generation unit; Parallel connection inserts meritorious absorption circuit between said contactor and reactive compensation module; Switch is electronic switch or mechanical switch, and electronic switch comprises anti-parallel thyristor or inverse parallel GTO.Present embodiment is an example with the anti-parallel thyristor valve of electronic switch; Be used for when the voltage dip fault appears in network system, cutting off the wind-powered electricity generation unit to the meritorious passage of network system feed-in, and after network system voltage recovers, fast the wind-powered electricity generation unit be communicated with network system.Reactive compensation module is a Shunt Capacitor Unit, the reactive power of needs when being used to compensate the wind-powered electricity generation unit and normally moving.Meritorious absorption circuit is used for absorbing after network system voltage dip, said switch break off, the active power that the wind-powered electricity generation unit sends.
Concrete, as shown in Figure 2, the end line of three phase network is made as A, B and C, and between wind-powered electricity generation unit and network system, near the local cascaded inverse parallel connection thyristor valve of network system, thyristor valve comprises 3 groups of anti-parallel thyristors, is connected on respectively on end line A, B and the C.Parallel connection inserts three-phase contactor between anti-parallel thyristor valve and wind-powered electricity generation unit, is connected through power line A1, B1 and C1.The three-phase contactor other end is connected with power line A2, B2 and C2.Compensation capacitors is connected on power line A2, B2 and the C2.Compensation capacitors comprises 3 groups of electric capacity, and 3 groups of electric capacity are connected on power line A2, B2 and the C2.Parallel connection inserts meritorious absorption circuit between contactor and compensation capacitors, is connected through power line A3, B3 and C3.Meritorious absorption circuit comprises reactor, the uncontrollable rectifier bridge of three-phase and discharge circuit; With after the uncontrollable rectifier bridge of three-phase is connected, parallelly connected with said discharge circuit, another side is connected with power line A3, B3 and C3 on one side for 3 reactors, each reactor.
The said discharge circuit of present embodiment comprises that discharge resistance R, fly-wheel diode, discharge IGBT and IGBT buffering absorb circuit; Connect with discharge IGBT after discharge resistance R and the fly-wheel diode parallel connection, discharge IGBT and IGBT buffering absorb the circuit parallel connection.The fly-wheel diode on discharge resistance R next door is in order to suppress the overvoltage that stray inductance produces in the loop, the afterflow path to be provided, and the fly-wheel diode negative electrode links to each other with positive bus-bar, and anode links to each other with the IGBT collector electrode.Recover in case the fault detect loop detects network system voltage, anti-parallel thyristor drops into immediately, and IGBT locking at once makes the meritorious circuit that absorbs stop meritorious the absorption.
The said IGBT buffering of present embodiment absorbs circuit and comprises resistance R 1, electric capacity and diode; Resistance R 1 and capacitances in series, diode is parallelly connected with said resistance R 1.Buffering absorbs circuit and has effectively suppressed discharge IGBT shutoff surge voltage and opened impulse current.
The electronic switching device of low-voltage traversing device can adopt the wind-cooling heat dissipating scheme, and the discharge resistance of meritorious absorption portion can place in the same air channel, need not to dispose separately cooling measure; Perhaps adopt the heat pipe heat radiation mode.
Present embodiment is as shown in Figure 5 to the control method sketch map of low-voltage traversing device, specifically comprises the steps:
(1) said contactor is closed;
(2) judge whether network system the voltage dip fault occurs, if do not break down, then closed said switch is communicated with between network system and the wind-powered electricity generation unit; If the voltage dip fault occurs, carry out step (3);
(3) break off said switch, the conducting of controller control discharge IGBT, meritorious absorption circuit absorbs the active power that the wind-powered electricity generation unit sends; The reactive power that reactive compensation module compensation wind-powered electricity generation unit needs when normally moving; Recover if detect the network system three-phase voltage, carry out step (4);
(4) closed said switch, the locking discharge IGBT is forbidden meritorious absorption circuit work, recovers the energy exchange passage between wind-powered electricity generation unit and the network system.
To the lock control of separating of discharge IGBT, be to produce corresponding PWM discharge trigger impulse according to the detected network system electric voltage dropping degree of depth, make active power consumption that the wind-powered electricity generation unit sends on discharge resistance R, guarantee that the set end voltage amplitude satisfies the condition that is incorporated into the power networks.
Because of the time very of short duration usually (about a few tens of milliseconds) between network system voltage dip age at failure; The wind-powered electricity generation unit set inertia is bigger, and the wind-powered electricity generation generating unit speed changes very little, is almost synchronous speed; After network system voltage recovered, the wind-powered electricity generation unit can be carried active power to network system again.Can make the wind-powered electricity generation unit pass through low-voltage state smoothly through such process.
Embodiment two
Present embodiment and embodiment one are basic identical, and distinctive points is:
The meritorious absorption circuit of present embodiment has another kind of form, and is as shown in Figure 3.Comprise that promptly reactor, the uncontrollable rectifier bridge of three-phase, discharge resistance, discharge IGBT and IGBT buffering absorb circuit; 3 reactors, each reactor are connected with said discharge resistance and the uncontrollable rectifier bridge of said three-phase successively, and the uncontrollable rectifier bridge of said three-phase is parallelly connected with said discharge IGBT, and said discharge IGBT is parallelly connected with said IGBT buffering absorption circuit.
Control method to device is the same with embodiment one.
Embodiment three
In order to suppress wind-powered electricity generation unit machine end overvoltage, present embodiment on the basis of embodiment one or embodiment two between contactor and shunt capacitor parallel connection insert lightning arrester, shown in Fig. 4 (the meritorious absorption circuit form with embodiment one is an example).When wind-powered electricity generation unit machine end overvoltage, lightning arrester is connected with ground, avoids wind-powered electricity generation unit machine end overvoltage, and hardware is burnt out.Lightning arrester is placed in the circuit, is connected with three-phase contactor through power line A2, B2, C2.Reactive-load compensation capacitor is connected with power line A2, B2, C2 through power line A3, B3, C3 with meritorious absorption circuit.For other control methods of circuit, all identical with embodiment one or embodiment two.
Should be noted that at last: combine the foregoing description technical scheme of the present invention only to be described but not its restriction.Under the those of ordinary skill in field be to be understood that: those skilled in the art can specific embodiments of the invention make amendment or are equal to replacement, but these modifications or change are all among the claim protection range that application is awaited the reply.