CN204517422U - Preventing distributed electricity generation system pours in down a chimney the system of electrical power to electrical network - Google Patents

Abstract

The utility model relates to a kind of preventing distributed electricity generation system pours in down a chimney system from electrical power to electrical network, this system is made up of electrical network, photovoltaic DC-to-AC converter, isolating transformer, sampling conditioning plate and control circuit board, this system is by the inverse probability of monitoring network, and by the instruction of control algolithm generation current, photovoltaic DC-to-AC converter adjusts power output according to current-order, ensures that the electrical power that distributed generation system exports and bearing power match.Dynamic Matching relation between the power that distributed generation system exports and bearing power ensure that the inverse probability of also site can not exceed the value of grid company defined, therefore, technical solutions of the utility model thoroughly can solve distributed generation system pours in down a chimney problem from power to electrical network.

Description

Preventing distributed electricity generation system pours in down a chimney the system of electrical power to electrical network

Technical field

The utility model relates to the control system that a kind of anti-electrical network pours in down a chimney electrical power, specifically, relate to a kind of preventing distributed electricity generation system pours in down a chimney system from electrical power (inverse probability) to electrical network, it is particularly suitable for pouring in down a chimney power for the anti-distributed generation system based on photovoltaic to electrical network.

Background technology

Along with China is using the development priority as new forms of energy such as photovoltaic generation, wind power generation.At present, photovoltaic, the electricity generation systems such as wind-force are mainly divided into stand alone generating system and the large class of grid-connected system two, wherein the main purpose of stand alone generating system is: be the load supplying in certain area, but due to solar energy, the new forms of energy such as wind energy are larger by the impact of natural environment and climate, there is obvious intermittence, in order to efficiently, reliably powering load, general employing grid-connected system, when generated output is greater than local load power demand, grid-connected system may to electrical network transmission of electric energy, based on the technical merit of current domestic electrical network and the factor of management of water equality aspect, State Grid Corporation of China requires that photovoltaic parallel in system is with irreversible generation mode access electrical network usually, namely photovoltaic parallel in system electricity can by local load consumption, unnecessary electric energy does not allow by low voltage distribution transformer superior grid transmission, for this reason, " State Grid Corporation of China's photovoltaic plant access electric power network technique regulation (trying) " clear stipulaties that State Grid Corporation of China puts into effect: when design of photovoltaic power station is irreversible synchronizing mode, reverse power proterctive equipment should be configured, when detecting that backward current exceedes 5% of the specified output of photovoltaic plant, photovoltaic plant and electrical network should disconnect by reverse power protection within 0.5-2 second.

For distributed grid-connected electricity generation system, preventing from dump energy being sent into electrical network is the requisite function of distributed grid-connected electricity generation system.For this function and State Grid Corporation of China, distributed grid-connected electricity generation system is put into effect " regulation "; domestic technology or the device having much more very enterprise (so special electrically, the special power supply of easy thing of relay, sunlight power supply, wound etc.) and research institution to study counterflow-preventing; and apply for corresponding patent, be used for protecting respective technology.

As Chinese patent " a kind of anti-reverse current device " (201120090188.5) discloses a kind of anti-backflow device, the technical scheme of this patent is: detected and the current/voltage of site by the measure and control instrument of voltage and electric current, judge whether that unnecessary electric energy sends into electrical network with this, and when there is unnecessary electric energy and entering electrical network, remedial measure is adopted to prevent inverse probability from sending into electrical network, what therefore this technical scheme was taked for inverse probability is the method for post, although serve certain effect, but still there is the situation unnecessary electric energy being admitted to electrical network, this may jeopardize the safe operation of electrical network.

The technical scheme of patent " one is applied to distributed power generation grid integration counterflow-preventing intelligent detecting method " (CN103779834) this patent is that the phase difference of voltage, electric current and voltage and current by detecting also site judges whether photovoltaic parallel in system there occurs adverse current, then determine whether disconnect inverter, namely patent CN103779834 adopts the anti-inverse probability of " on-off " mode.

The technical scheme of patent " a kind of grid-connected system counterflow-preventing method and apparatus " (CN102868181A) is the power output that power by detecting local load regulates inverter, thus prevent inverse probability from flowing into electrical network, anti-reverse power technology disclosed in above-mentioned patent is all opened loop control scheme, and this technical scheme bearing power existed in distributed generation system is not easy detection and inverse probability controls the shortcomings such as inaccuracy.

Utility model content

Based on the problems existed in prior art, the utility model provides a kind of preventing distributed electricity generation system pours in down a chimney system from electrical power to electrical network, wherein, comprising: distributed power generation unit and anti-reverse power device;

Described distributed power generation unit comprises electrical network and some photovoltaic DC-to-AC converters, each described photovoltaic DC-to-AC converter is connected with an isolating transformer all separately, and be connected to described electrical network by described isolating transformer, and each described photovoltaic DC-to-AC converter is connected to a local load by isolating transformer;

Described anti-reverse power device comprises connected sampling conditioning plate and control circuit board, described sampling conditioning plate obtains and flows into 3 line currents of described electrical network and 2 route voltages of described electrical network, and being sent to described control circuit board, nationality generates by described control circuit board the control unit that real-time current instruction is sent to each described photovoltaic DC-to-AC converter;

Wherein, be provided with a circuit breaker between each described photovoltaic DC-to-AC converter and isolating transformer, be also provided with a main breaker between described electrical network and described transformer, electrical network input is provided with Hall current sensor;

Each described photovoltaic DC-to-AC converter includes a three phase inverter bridge, and each described three phase inverter bridge all connects a string photovoltaic battery panel.

Above-mentioned preventing distributed electricity generation system pours in down a chimney the system of electrical power to electrical network, wherein, real-time current instruction is sent to the control unit of each described photovoltaic DC-to-AC converter by described control circuit board by 485 buses; This current-order is active current instruction and referenced reactive current.

Above-mentioned preventing distributed electricity generation system pours in down a chimney the system of electrical power to electrical network, wherein, three outputs of each described three phase inverter bridge are all in series with two inductance;

Be connected with the capacitor that a triangle connects between two inductance of any output series connection, three ends of this capacitor are connected respectively between two inductance of series connection.

The utility model provides a kind of preventing distributed electricity generation system pours in down a chimney control method from power to electrical network simultaneously, wherein, comprises the steps:

Step S1: the current/voltage of electrical network is sampled;

Step S2: convert the current/voltage of sampling, then calculate the electrical power of electrical network, described electrical power comprises active-power P struct.p, reactive power Pstruct.q and apparent power Pstruct.s;

Step S3: control reactive power Pstruct.q and amplitude limiting processing, obtain referenced reactive current;

Step S4: if the apparent power Pstruct.s flowing to electrical network is less than or equal to 5% of whole distributed generation system rated capacity, then order controls indexed variable Under5_control_flag=1, and controls active power, obtains active current instruction;

If the apparent power Pstruct.s flowing to electrical network is greater than a preset value of whole distributed generation system rated capacity, and active-power P struct.p<0 and control indexed variable Under5_control_flag=1 all sets up, then control active power;

If active-power P struct.p<0 and control indexed variable Under5_control_flag=0 all sets up, then increase active current current-order gradually, realize the soft start of inverter;

If the apparent power Pstruct.s flowing to electrical network is greater than a preset value of whole distributed generation system rated capacity, and active-power P struct.p>0 and 1 second timing markers Over5_Time_Delay<40 set up, then control active power, export meritorious and current-order, if Over5_Time_Delay<40 is false, then allow active current instruction reset;

Step S5: send active current instruction and referenced reactive current to the inverter in distributed generation system by bus;

Step S6: each inverter regulates respective power output according to the current-order received, and electric current is connected to described electrical network;

Step S7: repeat step S1 ~ step S6, until the power flowing to electrical network is 0, pours in down a chimney power to prevent distributed generation system to electrical network.

Above-mentioned method, wherein, obtains current i in electrical network sampling _{g α}, i _gb, i _gcand voltage u _ab, u _acafter, carry out Clark conversion to the current/voltage of sampling, the formula of its conversion is as follows:

$\left[\begin{array}{c}{i}_{\mathrm{g\&alpha;}}\\ i_{\mathrm{g\&beta;}}\end{array}\right]=\sqrt{\frac{2}{3}}\left[\begin{array}{ccc}1& -\frac{1}{2}& -\frac{1}{2}\\ 0& \frac{\sqrt{3}}{2}& -\frac{\sqrt{3}}{2}\end{array}\right]\&CenterDot;\left[\begin{array}{c}{i}_{\mathrm{ga}}\\ i_{\mathrm{gb}}\\ i_{\mathrm{gc}}\end{array}\right];$ ①

$\left[\begin{array}{c}{u}_{\mathrm{g\&alpha;}}\\ u_{\mathrm{g\&beta;}}\end{array}\right]=\sqrt{\frac{2}{3}}\left[\begin{array}{cc}\frac{1}{2}& \frac{1}{2}\\ -\frac{\sqrt{3}}{2}& \frac{\sqrt{3}}{2}\end{array}\right]\&CenterDot;\left[\begin{array}{c}{u}_{\mathrm{ab}}\\ u_{\mathrm{ac}}\end{array}\right];$ ②

Wherein, 1. formula is the formula of current transformation, and 2. formula is the formula of voltage transformation;

I _{g α}, i _{g β}be respectively the grid-connected current component on α axle and the component on β axle in α β coordinate system;

U _{g α}and u _{g β}be respectively the line voltage component on α axle and the component on β axle in α β coordinate system.

Above-mentioned method, wherein, calculates the electrical power flowing into electrical network according to instantaneous power theory:

Pstruct.p＝u _gα·i _gα+u _gβ·i _gβ； ③

Pstruct.q＝u _gβ·i _gα-u _gα·i _gβ； ④

$\mathrm{Pstruct}.s=\sqrt{{\mathrm{Pstruct}.p}^2+{\mathrm{Pstruct}.q}^2};$ ⑤

Wherein, 3. formula is the computing formula of active-power P struct.p, and 4. formula is the computing formula of reactive power Pstruct.q, and 5. formula is the computing formula of apparent power Pstruct.s.

Above-mentioned method, wherein, described preset value is 5%.

Above-mentioned method, wherein, in step s3, utilizes reactive power Pstruct.q divided by the rated capacity Sn of whole distributed generation system, obtains q_quo, then use reactive power instruction q ^*subtract q_quo, obtain idle deviation, by the idle deviation of proportional integral algorithm process, obtain referenced reactive current.

Above-mentioned method, wherein, in step s 4 which, utilizes active-power P struct.p divided by the rated capacity Sn of whole distributed generation system, obtains p_quo, then use active power instruction p ^*subtract p_quo, obtain meritorious deviation, to gain merit deviation by proportional integral algorithm process, obtain active current instruction.

Above-mentioned method, wherein, in step s 5, while transmission active current instruction and referenced reactive current, touches the instruction of screen display grid-connected current, line voltage, inverse probability, power factor, active current/reactive current by one.

Accompanying drawing explanation

By reading the detailed description done non-limiting example with reference to the following drawings, the utility model and feature, profile and advantage will become more obvious.Mark identical in whole accompanying drawing indicates identical part.Deliberately proportionally do not draw accompanying drawing, focus on purport of the present utility model is shown.

The preventing distributed electricity generation system that Fig. 1 provides for the utility model pours in down a chimney the schematic diagram of the system of electrical power to electrical network;

Fig. 2 A and Fig. 2 B is the control block diagram of the anti-reverse power device of the utility model;

Fig. 3 is the control program flow chart of the anti-reverse power device of the utility model.

Embodiment

In the following description, give a large amount of concrete details to provide to understand more thoroughly the utility model.But, it is obvious to the skilled person that the utility model can be implemented without the need to these details one or more.In other example, in order to avoid obscuring with the utility model, technical characteristics more well known in the art are not described.

In order to thoroughly understand the utility model, by proposing detailed step and detailed structure in following description, to explain the technical solution of the utility model.Preferred embodiment of the present utility model is described in detail as follows, but except these are described in detail, the utility model can also have other execution modes.

The utility model provides a kind of preventing distributed electricity generation system pours in down a chimney control system from electrical power to electrical network, and with reference to shown in Fig. 1, it comprises distributed power generation unit and anti-reverse power device.

Distributed power generation unit comprises electrical network (that is and site) and some photovoltaic DC-to-AC converters.In the utility model, this distributed power generation unit includes the photovoltaic DC-to-AC converter being no more than at most 32, only with 2 elaborations in the utility model.Photovoltaic DC-to-AC converter is connected with an isolating transformer T all separately, and each photovoltaic DC-to-AC converter is all connected to electrical network by the isolating transformer T connected separately.In addition, each photovoltaic DC-to-AC converter is connected to a local load by isolating transformer.

Anti-reverse power device comprises connected sampling conditioning plate and control circuit board, and sampling conditioning plate obtains the 3 line current (current i flowing into described electrical network _ga, i _gb, i _gc) and 2 route voltage (u _ab, u _ac), and be sent to control circuit board, nationality generates by control circuit board the control unit that real-time active current and reactive current are sent to each photovoltaic DC-to-AC converter.Optional but unrestricted, TMS320F28335 chip can be adopted to be the control circuit board of core.

Optional at the utility model one but in embodiment not as restriction, between each photovoltaic DC-to-AC converter and isolating transformer, be provided with a circuit breaker, so independently control each photovoltaic DC-to-AC converter with the conducting state of electrical network.Such as in FIG, a circuit breaker K1 is provided with between photovoltaic DC-to-AC converter 1 and isolating transformer T1, a circuit breaker K2 is provided with between photovoltaic DC-to-AC converter 2 and isolating transformer T2, nationality can realize photovoltaic DC-to-AC converter 1 by circuit breaker K1 and to be connected with electrical network or to disconnect, and nationality can realize photovoltaic DC-to-AC converter 2 by circuit breaker K2 and to be connected with electrical network or to disconnect.

The utility model one optional but not as restriction embodiment in, between electrical network and transformer, be also provided with a circuit breaker K3.As shown in Figure 1, because the output of each isolating transformer T1, T2 all converges to electrical network, therefore between the main line converged, be provided with a circuit breaker K3, can realize cutting off contacting between all photovoltaic DC-to-AC converters and electrical network by this circuit breaker K3 simultaneously.

The utility model one optional but not as restriction embodiment in, each photovoltaic DC-to-AC converter includes a three phase inverter bridge, and each three phase inverter bridge all connects a string photovoltaic battery panel (PV).Meanwhile, in another optional embodiment, also can only provide a string photovoltaic battery panel, and this photovoltaic battery panel is connected to the input of all photovoltaic DC-to-AC converters simultaneously.

The utility model one optional but not as restriction embodiment in, real-time current instruction is sent to the control unit of each photovoltaic DC-to-AC converter by control circuit board by 485 buses.

The utility model one optional but not as restriction embodiment in, also comprise a touch display screen, for showing the instruction of grid-connected current, line voltage, inverse probability, power factor, active current and reactive current in real time.User intuitively can understand parameters by display screen, convenient and swift.In an optional embodiment, the display screen of DOP-B03S211 model can be adopted.

The utility model one optional but not as restriction embodiment in, also comprise three Hall current sensors, be arranged on the input of electrical network.

The utility model one optional but not as restriction embodiment in, three outputs of each three phase inverter bridge are all in series with two inductance.With reference to shown in Fig. 1, three outputs of the three phase inverter bridge in photovoltaic DC-to-AC converter 1 are all worn and are in series with two inductance, and a wherein output of such as three phase inverter bridge is in series with inductance L _a1and L _ga1.

Optional at the utility model one but in embodiment not as restriction, each photovoltaic DC-to-AC converter also comprises the capacitor that a triangle connects, and three ends of this capacitor are connected respectively between two inductance that any output of photovoltaic DC-to-AC converter is connected.With reference to shown in Fig. 1, there is the capacitor that a triangle connects in photovoltaic DC-to-AC converter 1, by electric capacity C _a1, C _b1, C _c1three electric capacity couple together with leg-of-mutton connected mode, and are connected respectively between two inductance that any output of three phase inverter bridge is connected.

The utility model additionally provides preventing distributed electricity generation system pours in down a chimney control method from power to electrical network simultaneously, with reference to shown in Fig. 3, specifically comprises the steps.

Step S1: the electric current of electrical network and voltage are sampled.

Step S2: convert the electric current of sampling and voltage, then calculate the electrical power of electrical network, electrical power comprises active-power P struct.p, reactive power Pstruct.q and apparent power Pstruct.s.

Step S3: control reactive power Pstruct.q and amplitude limiting processing, obtain referenced reactive current.

Step S4: if the apparent power Pstruct.s flowing to electrical network is less than or equal to 5% of whole distributed generation system rated capacity, then order controls indexed variable Under5_control_flag=1, and controls active power, obtains active current instruction.

If the apparent power Pstruct.s flowing to electrical network is greater than a preset value of whole distributed generation system rated capacity, and active-power P struct.p<0 and control indexed variable Under5_control_flag=1 all sets up, then control active power.

If active-power P struct.p<0 and control indexed variable Under5_control_flag=0 all sets up, then increase active current current-order gradually, realize the soft start of inverter.

If the apparent power Pstruct.s flowing to electrical network is greater than a preset value of whole distributed generation system rated capacity, and active-power P struct.p>0 and 1 second timing markers Over5_Time_Delay<40 set up, then control active power, export meritorious/current-order, if Over5_Time_Delay<40 is false, then allow active current instruction reset.

Step S5: send active current instruction and referenced reactive current to the inverter in distributed generation system by bus, such as, adopt broadcast mode to communicate with each inverter in distributed generation system by 485 buses.

Step S6: each inverter regulates respective power output according to the current-order received, and electric current is connected to electrical network.

Step S7: repeat step S1 ~ step S6, until the power flowing to electrical network is 0, pours in down a chimney power to prevent distributed generation system to electrical network.

The utility model one optional but not as restriction embodiment in, electrical network sampling obtain current i _ga, i _gb, i _gcand voltage u _ab, u _acafter, carry out Clark conversion to the electric current of sampling and voltage, formula of its conversion is as follows:

$\left[\begin{array}{c}{i}_{\mathrm{g\&alpha;}}\\ i_{\mathrm{g\&beta;}}\end{array}\right]=\sqrt{\frac{2}{3}}\left[\begin{array}{ccc}1& -\frac{1}{2}& -\frac{1}{2}\\ 0& \frac{\sqrt{3}}{2}& -\frac{\sqrt{3}}{2}\end{array}\right]\&CenterDot;\left[\begin{array}{c}{i}_{\mathrm{ga}}\\ i_{\mathrm{gb}}\\ i_{\mathrm{gc}}\end{array}\right];$ ①

$\left[\begin{array}{c}{u}_{\mathrm{g\&alpha;}}\\ u_{\mathrm{g\&beta;}}\end{array}\right]=\sqrt{\frac{2}{3}}\left[\begin{array}{cc}\frac{1}{2}& \frac{1}{2}\\ -\frac{\sqrt{3}}{2}& \frac{\sqrt{3}}{2}\end{array}\right]\&CenterDot;\left[\begin{array}{c}{u}_{\mathrm{ab}}\\ u_{\mathrm{ac}}\end{array}\right];$ ②

Wherein, 1. formula is the formula of current transformation, and 2. formula is the formula of voltage transformation;

I _{g α}, i _{g β}be respectively the grid-connected current component on α axle and the component on β axle in α β coordinate system;

U _{g α}and u _{g β}be respectively the line voltage component on α axle and the component on β axle in α β coordinate system.

Optional at the utility model one but in embodiment not as restriction, calculate according to instantaneous power theory and flow into the electrical power of electrical network:

Pstruct.p＝u _gα·i _gα+u _gβ·i _gβ③

Pstruct.q＝u _gβ·i _gα-u _gα·i _gβ④

$\mathrm{Pstruct}.s=\sqrt{{\mathrm{Pstruct}.p}^2+{\mathrm{Pstruct}.q}^2}$ ⑤

Wherein, 3. formula is the computing formula of active-power P struct.p, and 4. formula is the computing formula of reactive power Pstruct.q, and 5. formula is the computing formula of apparent power Pstruct.s.

The utility model one optional but not as restriction embodiment in, above-mentioned preset value is 5%.

The utility model one optional but not as restriction embodiment in, in step s3, utilize reactive power Pstruct.q divided by the rated capacity Sn of whole distributed generation system, obtain q_quo, then use reactive power instruction q ^*subtract q_quo, obtain idle deviation, by the idle deviation of proportional integral algorithm process, obtain referenced reactive current.Can refer to shown in accompanying drawing 2B.

The utility model one optional but not as restriction embodiment in, in step s 4 which, utilize active-power P struct.p divided by the rated capacity Sn of whole distributed generation system, obtain p_quo, then use active power instruction p ^*subtract p_quo, obtain meritorious deviation, to gain merit deviation by proportional integral algorithm process, obtain active current instruction.Can refer to shown in accompanying drawing 2A.

The utility model one optional but not as restriction embodiment in, in step s 5, while transmission active current instruction and referenced reactive current, touch the instruction of screen display grid-connected current, line voltage, inverse probability, power factor, active current/reactive current by one.

Outstanding effect of the present utility model is: one, the power (inverse probability) flowing to electrical network is in controllable state all the time, even if because inverse probability appears in load disturbance, inverse probability also can control to be 0 by the utility model in 2 seconds, did not need to make inverter in distributed generation system from net; They are two years old, distributed generation system can be made to export power large as far as possible, can in " State Grid Corporation of China's photovoltaic plant access electric power network technique regulation (trying) " official hour, the utility model can make distributed generation system be 0 to the electrical power that electrical network pours in down a chimney or reach the value of " State Grid Corporation of China's photovoltaic plant access electric power network technique specifies (trying) " defined.

Above preferred embodiment of the present utility model is described.It is to be appreciated that the utility model is not limited to above-mentioned particular implementation, the equipment wherein do not described in detail to the greatest extent and structure are construed as to be implemented with the common mode in this area; Any those of ordinary skill in the art, do not departing under technical solutions of the utility model ambit, the Method and Technology content of above-mentioned announcement all can be utilized to make many possible variations and modification to technical solutions of the utility model, or being revised as the Equivalent embodiments of equivalent variations, this does not affect flesh and blood of the present utility model.Therefore, every content not departing from technical solutions of the utility model, according to technical spirit of the present utility model to any simple modification made for any of the above embodiments, equivalent variations and modification, all still belongs in the scope of technical solutions of the utility model protection.

Claims (3)

1. preventing distributed electricity generation system pours in down a chimney a system for electrical power to electrical network, it is characterized in that, comprising: distributed power generation unit and anti-reverse power device;

Described distributed power generation unit comprises electrical network and some photovoltaic DC-to-AC converters, each described photovoltaic DC-to-AC converter is connected with an isolating transformer all separately, and be connected to described electrical network by described isolating transformer, and each described photovoltaic DC-to-AC converter is connected to a local load by isolating transformer;

Described anti-reverse power device comprises connected sampling conditioning plate and control circuit board, described sampling conditioning plate obtains and flows into 3 line currents of described electrical network and 2 route voltages of described electrical network, and being sent to described control circuit board, nationality generates by described control circuit board the control unit that real-time current instruction is sent to each described photovoltaic DC-to-AC converter;

Wherein, be provided with a circuit breaker between each described photovoltaic DC-to-AC converter and isolating transformer, be also provided with a main breaker between described electrical network and described transformer, electrical network input is provided with Hall current sensor;

Each described photovoltaic DC-to-AC converter includes a three phase inverter bridge, and each described three phase inverter bridge all connects a string photovoltaic battery panel.

2. preventing distributed electricity generation system as claimed in claim 1 pours in down a chimney the system of electrical power to electrical network, it is characterized in that, real-time current instruction is sent to the control unit of each described photovoltaic DC-to-AC converter by described control circuit board by 485 buses;

Described real-time current instruction is active current instruction and referenced reactive current.

3. preventing distributed electricity generation system as claimed in claim 1 pours in down a chimney the system of electrical power to electrical network, it is characterized in that, three outputs of each described three phase inverter bridge are all in series with two inductance;

Be connected with the capacitor that a triangle connects between two inductance of any output series connection, three ends of this capacitor are connected respectively between two inductance of series connection.