A new energy station bidirectional transient reactive power measurement optimization method

Abstract

The application discloses a new energy station bidirectional transient reactive power measurement optimization method, which firstly establishes a PQ rectangular coordinate system, then draws a maximum operation boundary in the PQ rectangular coordinate system, and then calculates reverse transient reactive power margins and forward transient reactive power margins of the measured and controlled station's transient reactive power generating elements, calculates an optimal area of a PQ point according to the reverse transient reactive power margins and the forward transient reactive power margins of the generating elements, and prewarns and optimally controls the present operation PQ point of the transient reactive power generating elements in the station through the optimal area. The application realizes the coordinated preventive control of the transient reactive power of the generating elements in the measured and controlled station, so that the new energy station has maximized bidirectional transient reactive power reserves in real time, ensures that the maximum reverse and forward transient reactive power can be provided to inhibit the voltage rise or drop during the state change, abnormality or fault process of the power grid, supports the voltage stability of the station, and no oscillation source occurs.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of new energy station transient reactive power measurement, and particularly relates to a new energy station bidirectional transient reactive power measurement optimization method. BACKGROUND

[0002] With the increasing penetration of wind power, photovoltaic power, reactive power compensation, energy storage, and direct current new energy power generation systems, the power grid exhibits weak grid or even extremely weak grid characteristics. Due to the lack of reactive power collaborative optimization control technology in the operation mode of new energy stations and collection stations, transient reactive power control is improper and transient reactive power is insufficient. In addition, due to the randomness, intermittency, and volatility of new energy, and due to changes in the state of the power grid or the occurrence of short circuits, disturbances, and other faults, transient overvoltage and low voltage exist in the station, which induces phase-locked failure of electronic equipment, wideband oscillation due to current limit saturation switching, and other problems, bringing severe challenges to the stable and efficient operation of new energy grid-connected power generation systems.

[0003] Chinese Patent CN112366698B discloses a method for monitoring the stability of a wide-area power grid based on PQ groups and preventing and identifying oscillation sources. The method draws the maximum operating PQ range of a local power grid PQ group, monitors whether the PQ group falls outside the maximum operating PQ range, and if so, issues an alarm signal indicating that the power grid is unstable. The above method draws the maximum operating PQ range, but does not provide the optimal operating PQ range, cannot completely address the problems caused by power grid oscillation and various power grid faults, and cannot guarantee the stability of the power grid operation. In addition, the method lacks reactive power collaborative optimization, which can easily lead to improper transient reactive power control and transient reactive power deficiency. SUMMARY

[0004] The present application aims to provide a new energy station bidirectional transient reactive power measurement optimization method to address the above problems. By accurately measuring the bidirectional transient reactive power of the new energy station, the station operation and maintenance personnel can refer to the measured transient reactive power data to optimize the control of the station. Through optimization control, the transient reactive power circulating current in the station can be removed, and the overall reverse and forward transient reactive power margin of the measured and controlled station can be maximized. In the event of power grid voltage disturbance or fault, the overall station can provide maximum reverse and forward transient reactive power to suppress voltage rise or fall, support voltage stability, and avoid the occurrence of oscillation tripping or off-grid accidents.

[0005] To achieve the above application purposes, the technical solutions adopted by the present application are as follows:

[0006] According to one aspect of the present application, a new energy station bidirectional transient reactive power measurement optimization method is provided, comprising the following steps:

[0007] S1, the network configuration type converter with voltage change / reactive power automatic regulation response capability and other reactive power generation equipment with voltage change / reactive power automatic regulation response capability in the station are classified as reactive power generation elements, and the reactive power generated by the reactive power generation element with voltage change / reactive power fast automatic regulation response capability in the station is defined as transient reactive power;

[0008] S2, a PQ rectangular coordinate system of the reactive power generation element is set, wherein the P axis is arranged vertically and the Q axis is arranged horizontally, a PQ safety boundary of the generation element is drawn on the PQ rectangular coordinate system, and a PQ point of the reactive power generation element is drawn on the PQ rectangular coordinate system, a horizontal line is drawn through the PQ point to intersect the lower limit and the upper limit of the PQ safety boundary, the distance between the two points is the adjustable range of the reactive power of the generation element, the distance from the PQ point to the intersection point of the lower limit of the PQ safety boundary is the adjustable margin of the reverse reactive power, and the distance from the PQ point to the intersection point of the upper limit of the PQ safety boundary is the adjustable margin of the forward reactive power;

[0009] S3, when the reactive power generation element is put into the end voltage change / reactive power fast automatic tracking regulation mode, the reverse and forward reactive power adjustable margins of the reactive power generation element are respectively regarded as the reverse and forward transient reactive power margins of the generation element;

[0010] S4, a PQ safety domain boundary of the reactive power generation element is drawn, and the position of the PQ point of the reactive power generation element is defined in the PQ safety domain boundary;

[0011] S5, the generation element with voltage change / reactive power fast automatic regulation response capability in the station is divided into a transient reactive power generation element group;

[0012] S6, a group of transient reactive power generation elements capable of providing transient reactive power in the station is selected, the ratio of the reverse transient reactive power margin to the forward transient reactive power margin of each transient reactive power generation element is calculated, the minimum value and the maximum value of the ratio of the reverse transient reactive power margin to the forward transient reactive power margin are obtained, and the reverse transient reactive power margin and the forward transient reactive power margin of the transient reactive power generation element group are obtained according to the minimum value and the maximum value;

[0013] The ratio of the reverse transient reactive power margin to the forward transient reactive power margin of the transient reactive power generation element is:

[0014]

[0015] K i is the ratio of the reverse transient reactive power margin to the forward transient reactive power margin; E i is the PQ point of the transient reactive power generation element; E min·i is the intersection point of the PQ point of the transient reactive power generation element and the lower limit of the boundary of the PQ safety boundary; E min·i is the intersection point of the PQ point of the transient reactive power generation element and the upper limit of the boundary of the PQ safety boundary;

[0016] wherein, the reverse transient reactive power margin of the transient reactive power generation element group is:

[0017]

[0018] the forward transient reactive power margin of the transient reactive power generation element group is:

[0019]

[0020] ∑Q x- , ∑Q x+ are respectively the reverse and forward transient reactive power margin of x sets of transient reactive power generation elements in the station; K xmax , K xmin are respectively the maximum and minimum value of the reverse and forward transient reactive power margin ratio of the transient reactive power generation elements in the station; Q min·i , Q max·i are respectively the lower and upper limit of the reactive power of the i-th transient reactive power generation element;

[0021] S7, setting the transient reactive power PQ safety domain boundary of the reactive power generation element within the PQ safety domain boundary of the reactive power generation element and calculating the optimal position of the PQ point of the reactive power generation element, and setting the optimal region boundary of the PQ point of the reactive power generation element according to the optimal position of the PQ point;

[0022] S8, in the normal operation state, monitoring whether all the PQ points of the transient reactive power generation elements in the station are operated within the optimal region boundary of the PQ point of the transient reactive power generation element, if the PQ point of the transient reactive power generation element exceeds the optimal region boundary of the PQ point, an early warning is given and disposal is made; monitoring whether the optimal region boundary of the PQ point of the transient reactive power generation element is operated within the transient reactive power PQ safety domain boundary, if the optimal region boundary of the PQ point exceeds the transient reactive power PQ safety domain boundary, an early warning is given and disposal is made.

[0023] Preferably, in step S2, the transient reactive power PQ safety boundary is determined according to the operating parameters of the transient reactive power generation element.

[0024] Preferably, in step S4, the position of the PQ point of the reactive power generation element is:

[0025] The ordinate of the PQ point of the reactive power generation element is the per-unit value of the active power, and the abscissa of the PQ point of the reactive power generation element is determined by the reverse and forward reactive power adjustable margin ratio.

[0026] Preferably, the reverse and forward reactive power adjustable margin ratio of the PQ point of the reactive power generation element is:

[0027]

[0028] wherein, PQ point of the i-th reactive power generation element under the condition of active power P i ; Q Q min·i E i E i E max·i respectively, are the reverse reactive power adjustable margin and the forward reactive power adjustable margin of the i-th reactive power generation element.

[0029] Preferably, in step S6, the reverse transient reactive power margin and the forward transient reactive power margin of the whole transient reactive power generation element are optimized to a ratio K z :

[0030]

[0031] wherein n is the number of transient reactive power generation elements operating in the station, Q k is the abscissa of the operating PQ point of the k-th transient reactive power generation element, Q min·k is the abscissa of the intersection of the operating PQ point of the generation element and the lower limit of the maximum operating boundary reactive power, and Q max·k is the abscissa of the intersection of the operating PQ point of the generation element and the lower limit of the maximum operating boundary reactive power.

[0032] Preferably, in step S7, the transient reactive power PQ safety domain boundary is:

[0033] When the reactive power generation element PQ group operates within the transient reactive power PQ safety domain boundary of the reactive power generation element, it can ensure that various states can reserve certain reverse and forward transient reactive power, and during system disturbance or fault, the reactive power generation element group in the station can provide certain transient reactive power support for voltage stability, and all PQ points of the reactive power generation element group do not exceed the reactive power generation element PQ safety domain boundary, and can enter a new stable state after fault removal.

[0034] Preferably, in step S8, the treatment method comprises the following steps:

[0035] Increasing or decreasing the voltage of the upper-level power grid to restore the normal state of the station;

[0036] Or restore the normal state of the station by changing the tap changer of the station transformer.

[0037] Preferably, a transient reactive power coordination method for generation elements of a new energy station comprises a plurality of grid-forming converter groups composed of grid-forming converters and a plurality of reactive power generation device groups composed of reactive power generation devices, characterized in that it comprises the following steps:

[0038] The transient reactive power and the optimal region are calculated separately according to the groups, respectively.

[0039] When the reverse transient reactive power margin and the forward transient reactive power margin of the transient reactive power network type converter and the transient reactive power generation device differ by more than a given threshold, an alarm is given, and by adjusting the reverse transient reactive power margin and the forward transient reactive power margin of the network type converter group in the field station to be equal to the reverse transient reactive power margin and the forward transient reactive power margin of the reactive power generation device group in the field station, the reverse transient reactive power margin and the forward transient reactive power margin of the entire field station are maximized.

[0040] In summary, by adopting the technical scheme, the present application has the following advantages:

[0041] The present application draws the PQ point safety region of the power generation element in the field station, calculates the reverse transient reactive power margin and the forward transient reactive power margin of the PQ point of the power generation element in the field station, obtains the optimal transient reactive power region according to the reverse transient reactive power margin and the forward transient reactive power margin, and gives a warning to the power generation element that exceeds the safety region or the optimal region, so that the new energy field station has maximized bidirectional transient reactive power reserve in real time, ensures that the maximum reverse and forward transient reactive power can be provided to suppress voltage rise or drop during the change, abnormality or failure of the power grid, supports voltage stability of the field station, and no oscillation source occurs. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 Primary system diagram of new energy field station;

[0043] Figure 2 Equivalent circuit diagram of new energy field station;

[0044] Figure 3 PQ safety boundary of network type converter;

[0045] Figure 4 PQ safety boundary of reactive power generation device;

[0046] Figure 5 PQ group safety domain of network type converter;

[0047] Figure 6 Boundary division diagram of PQ group safety domain of network type converter;

[0048] Figure 7 PQ group safety domain of reactive power generation device;

[0049] Figure 8 Boundary division diagram of PQ group safety domain of reactive power generation device. DETAILED DESCRIPTION

[0050] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and preferred embodiments. However, it should be noted that many details in the description are only for the purpose of making the reader have a thorough understanding of one or more aspects of the present application, and the aspects of the present application can be realized even without these specific details.

[0051] Please refer to Figures 1 to 6 , the present application provides a new energy station bidirectional transient reactive power measurement optimization method, and the technical solutions are as follows:

[0052] S1, in order to facilitate the reactive power optimization management of the station, the network type converter with voltage change / reactive power automatic regulation response capability and other reactive power generation equipment (only reactive power equipment) with voltage change / reactive power automatic regulation response capability in the station are classified as reactive power generation elements. The reactive power generated by the reactive power generation elements with voltage change / reactive power low-speed automatic regulation response capability in the station is classified as dynamic reactive power, and the reactive power generated by the reactive power generation elements with voltage change / reactive power fast automatic regulation response capability in the station is classified as transient reactive power. Although the network type converter and the reactive power generation equipment have the same voltage change / reactive power automatic regulation response mode, there is a big difference in the transient reactive power margin of the network type converter and the reactive power generation equipment as a whole in the station. In the process of reactive power optimization management, the network type converter and the reactive power generation equipment are managed in groups, so as to better calculate and optimize the reactive power distribution.

[0053] Specifically, the power generation elements of the new energy station are divided into two categories. One category is the power generation elements that generate both active power and reactive power, such as photovoltaic, wind power, energy storage devices, etc. These power generation elements are classified as network type converters, which have voltage change / reactive power low-speed automatic response capability under AVC regulation, and the reactive power generated by these network type converters is classified as dynamic reactive power. These network type converters have voltage change / reactive power fast automatic response capability under automatic device regulation, and the reactive power generated by these network type converters is classified as transient reactive power. The other category is the power generation elements that only generate reactive power, such as reactive power compensators and phase modulators, which are classified as reactive power generation equipment. These reactive power generation equipment have voltage change / reactive power low-speed automatic response capability under AVC regulation, and the reactive power generated by these reactive power generation equipment is classified as dynamic reactive power. These reactive power generation equipment have voltage change / reactive power fast automatic response capability under automatic device regulation, and the reactive power generated by these reactive power generation equipment is classified as transient reactive power. As shown in Figures 1-2 , Figure 1 is a one-time system diagram of a new energy station, Figure 2 is Figure 1 is an equivalent circuit diagram. The voltage at the grid connection point of the new energy station in Figure 2 can be obtained by measuring the loop The voltage at the end of the new energy converter The active power P iReactive power Q i , and Phase angle δ i It can also obtain the terminal voltage of reactive power generation equipment. Active power P j Reactive power Q j , and Phase angle δ j .

[0054] S2. Set up a rectangular coordinate system for the grid-type converter PQ, with the vertical and horizontal directions representing the active and reactive power directions, respectively. Draw the safety boundary of the grid-type converter PQ in the rectangular coordinate system, and draw the PQ point of the grid-type converter. Draw a horizontal line through the PQ point, intersecting the lower and upper limits of the PQ safety boundary at two points. The area between these two points is the reactive power adjustable range of the grid-type converter. The distance from the PQ point to the intersection point of the lower limit of the PQ safety boundary is the reverse reactive power adjustable margin, and the distance from the PQ point to the intersection point of the upper limit of the PQ safety boundary is the forward reactive power adjustable margin.

[0055] Specifically, such as Figure 3 As shown, a PQ rectangular coordinate system is established with P as the vertical axis and Q as the horizontal axis, where P represents active power and Q represents reactive power. The maximum operating boundary of the grid-type converter at point PQ is plotted on the PQ rectangular coordinate system. This maximum operating boundary of point PQ is the PQ safety boundary. When the operating point PQ exceeds this safety boundary, overcurrent of the converter, or overcurrent of the stator or rotor may occur, resulting in a protection failure.

[0056] like Figure 3 As shown, the active power of the i-th grid-type converter is P. i The P i The corresponding coordinates of point PQ are E i (Q i ,P i ), passing through point E i (Q i ,P i Draw a line segment E parallel to the Q-axis. min·i E max·i The intersection points of this line segment with the lower and upper limits of the PQ safety boundary are E and E, respectively. min·i (Q min·i ,P i E max·i (Q max·i ,P i ).

[0057] Calculate line segment E min·i E i Length, E min·i E i The i-th grid-type converter of length has an active power of P ireverse reactive power adjustable margin under the condition that the active power is P i E max·i the length of line segment E i E max·i the length of line segment E i forward reactive power adjustable margin under the condition that the active power is P

[0058] S3, when the grid-forming converter is put into the end voltage change / reactive power fast automatic tracking regulation mode, its reverse and forward reactive power adjustable margins are regarded as the reverse and forward transient reactive power margins of the grid-forming converter respectively; when the grid-forming converter is put into the end voltage change / reactive power low-speed automatic tracking regulation mode, its reverse and forward reactive power adjustable margins are regarded as the reverse and forward dynamic reactive power margins of the grid-forming converter respectively.

[0059] Specifically, when the grid-forming converter is put into the end voltage change / reactive power fast automatic tracking regulation mode, the lengths of line segment E min·i E i and line segment E i E max·i are regarded as the reverse and forward transient reactive power margins of the grid-forming converter respectively, which are also the reverse and forward transient reactive power reserve values, and the reverse or forward transient reactive power is used to suppress voltage rise or drop respectively. The transient reactive power reserve value of the grid-forming converter has two reserves in the positive and reverse directions, which have different effects.

[0060] When the grid-forming converter is put into the end voltage / reactive power low-speed (such as AVC regulation mode) automatic tracking regulation mode, the lengths of line segment E min·i E i and line segment E i E max·i are the reverse and forward dynamic reactive power adjustable margins of the grid-forming converter respectively, which are also the reverse and forward dynamic reactive power reserve values, and the reverse or forward dynamic reactive power is used to reduce or raise the terminal voltage of the grid-forming converter respectively. The dynamic reactive power reserve value of the grid-forming converter has two reserves in the positive and reverse directions.

[0061] The above describes that the transient reactive power and the dynamic reactive power of the grid-forming converter can exist simultaneously, the transient reactive power is used to suppress voltage amplitude disturbance in the transient process, and the dynamic reactive power can be used to change the working condition of the grid-forming converter in the steady state or excessive process.

[0062] S4. Set up a rectangular coordinate system for the reactive power generation equipment PQ, with the vertical and horizontal directions representing the active and reactive directions, respectively. Draw the safety boundary of the reactive power generation equipment PQ in the PQ rectangular coordinate system, and draw the point PQ of the reactive power generation equipment. Draw a horizontal line through the point PQ that intersects the lower and upper limits of the PQ safety boundary at two points. The area between these two points is the adjustable range of reactive power for the reactive power generation equipment. The distance from the intersection point of the PQ point and the lower limit of the PQ safety boundary is the reverse reactive power adjustable margin, and the distance from the intersection point of the PQ point and the upper limit of the PQ safety boundary is the forward reactive power adjustable margin.

[0063] Specifically, such as Figure 4 As shown, a Cartesian coordinate system PQ is established with P as the vertical axis and Q as the horizontal axis, where P represents active power and Q represents reactive power. Based on the maximum operating range of the reactive power generation equipment at point PQ during normal operation, the maximum operating boundary of point PQ is plotted on the PQ Cartesian coordinate system. The maximum operating boundary of point PQ is defined as follows: when the operating point PQ exceeds this boundary, overcurrent in the converter, or overcurrent in the stator or rotor, may trigger protection mechanisms. The maximum operating boundary is the boundary between normal and abnormal operation at point PQ, also known as the PQ safety boundary, and can be determined based on the parameters of the reactive power generation equipment.

[0064] like Figure 4 As shown, the active power of the j-th dynamic reactive power generator is P. j The P j The corresponding coordinates of point PQ are E j (Q j ,P j ), passing through point E j (Q j ,P j Draw a line segment E parallel to the Q-axis. min·j E max·j The intersection points of this line segment and the PQ safety boundary are E and E respectively. min·j (Q min·j ,P j E max·j (Q max·j ,P j ).

[0065] Calculate line segment E min·j E j Length, E min·j E j The length of the j-th reactive power generator is P. j Reverse reactive power adjustability margin under the given conditions; calculate line segment E i E max·i Length, E i E max·i The i-th reactive power generator of length has an active power of P. i Positive reactive power adjustability margin under the condition

[0066] S5. When the reactive power generation equipment is put into the terminal voltage change / reactive power fast automatic tracking adjustment mode, its reverse and forward reactive power adjustable margins are regarded as the reverse and forward transient reactive power margins of the reactive power generation equipment, respectively; when the reactive power generation equipment is put into the terminal voltage change / reactive power low-speed automatic tracking adjustment mode, its reverse and forward reactive power adjustable margins are regarded as the reverse and forward dynamic reactive power margins of the reactive power generation equipment, respectively.

[0067] When the reactive power generation equipment is put into the terminal (or busbar) voltage change / reactive power fast automatic tracking adjustment mode, line segment E min·j E j and line segment E i E max·i The lengths represent the reverse and forward transient reactive power margins of the reactive power generation element, and are also the reverse and forward transient reactive power reserve values. When the reactive power generation element is put into automatic tracking regulation mode (such as AVC regulation mode) at the end (or grid connection point) voltage / reactive low speed, the length of line segment E is... min·j E j and line segment E i E max·i The lengths represent the reverse and forward dynamic reactive power margins of the reactive power generation element, and are also the reverse and forward dynamic reactive power reserve values.

[0068] The above situation illustrates that transient reactive power and dynamic reactive power of reactive power generation equipment can coexist. Transient reactive power is used to suppress voltage amplitude disturbances during transient processes, while dynamic reactive power is used to change the operating conditions of the power generation equipment during steady-state or transitional processes.

[0069] S6. Draw the PQ safety domain boundary of the grid-type converter. The vertical and horizontal directions represent the active and reactive power directions, respectively. The vertical coordinate of point PQ is in the per-unit value of active power. The position of point PQ on the PQ safety domain boundary of the grid-type converter: The vertical coordinate of point PQ is in the per-unit value of active power. The horizontal position of point PQ is on its active power straight line, determined by the ratio of its reverse and forward reactive power adjustable margins.

[0070] Specifically, a shared PQ rectangular coordinate system is established for the PQ group. The safety domain boundary of the grid-type converters is drawn on this system, determining the position of each grid-type converter's PQ point within the PQ rectangular coordinate system. To facilitate the calculation of the overall dynamic and transient reactive power reserves of the power station, such as... Figure 5 As shown, the safety domain boundary of the PQ group of the grid-type converter is set. The active power P of the i-th grid-type converter i Points P and Q under the given conditions. Segments O1 and O2, representing reactive power, are arranged horizontally, while segments O1 and O2, representing active power of the i-th grid-type converter, are arranged horizontally. Vertical arrangement Perpendicular to O1O2, intersecting O1O2 at point O. The length of the line segment represents the active power P of the i-th grid-forming converter i The unit P pu·i Passing through the point The line segment Parallel to O1O2, the line segment The reactive power lower limit boundary of the PQ group security domain is at the point The reactive power upper limit boundary of the PQ group security domain is at the point

[0071] The following formula can be obtained through calculation:

[0072]

[0073] In the formula, the line segment E min·i E i and the line segment E i E max·i are the reverse reactive power adjustable margin and the forward reactive power adjustable margin of the i-th grid-forming converter respectively. The above formula shows that the ratio of the distance of the i-th grid-forming converter operating at the PQ point to the reactive power lower limit and the reactive power upper limit of the PQ group security domain boundary is equal to the ratio of the reverse reactive power adjustable margin E min·i E i and the forward reactive power adjustable margin E i E max·i .

[0074] S7, select a group of grid-forming converters in the field station that can provide transient reactive power, calculate the reverse and forward transient reactive power margin ratio of each transient reactive power grid-forming converter, wherein the minimum value of the reverse and forward transient reactive power margin ratio and the maximum value of the reverse and forward transient reactive power margin ratio determine the size of the reverse and forward transient reactive power margin of the grid-forming converter group.

[0075] Specifically, assuming that there are x grid-forming converters that can provide transient reactive power in the new energy field station, the ratio of the reverse transient reactive power margin and the forward transient reactive power margin of the i-th grid-forming converter that can provide transient reactive power is K i :

[0076]

[0077] The ratio of the reverse transient reactive power margin and the forward transient reactive power margin of the first to the x-th transient reactive power grid-forming converter is K1, K2, … K i , … K x , wherein the minimum value is K xmin and the maximum value is K xmax .

[0078] The reverse transient reactive power margin of the x grid-forming converter groups in the new energy station is:

[0079]

[0080] The forward transient reactive power margin of the x grid-forming converter groups in the new energy station is:

[0081]

[0082] Wherein, ∑Q x- , ∑Q x+ are the reverse and forward transient reactive power margins of the x grid-forming converter groups in the station respectively.

[0083] K xmax , K xmin are the maximum and minimum values of the reverse and forward transient reactive power margin ratios of the x grid-forming converters in the station respectively.

[0084] Q min·i , Q max·i are the lower and upper reactive power values of the i grid-forming converter.

[0085] S8, setting the grid-forming converter transient reactive power PQ safety domain boundary within the grid-forming converter PQ safety domain boundary, calculating the grid-forming converter PQ point optimal position, and setting the grid-forming converter PQ point optimal area boundary.

[0086] Specifically, the grid-forming converter transient reactive power PQ safety domain boundary: when the grid-forming converter PQ group operates within the grid-forming converter transient reactive power PQ safety domain boundary, it can ensure that a certain reverse and forward transient reactive power is reserved under various states, and during the system disturbance or fault process, the grid-forming converter group in the station can provide a certain transient reactive power support for voltage stability, and all PQ points of the grid-forming converter group can enter a new stable state after fault removal.

[0087] Calculating the grid-forming converter PQ point optimal position: first, under the condition that the total load of the x transient reactive grid-forming converters in the station is unchanged, the optimal ratio K x of the reverse transient reactive power margin and the forward transient reactive power margin of the station is calculated. x According to the optimal ratio K x of the reverse transient reactive power margin and the forward transient reactive power margin of the station, the optimal PQ points corresponding to the active power per unit value of the x transient reactive grid-forming converters are drawn, and all the optimal PQ points form the transient reactive grid-forming converter PQ point optimal position.

[0088] For example, suppose a power station has x grid-type converters with automatic fast response for reactive power / voltage, where the operating point PQ of the i-th grid-type converter is E. i (Q i ,P i The reverse transient reactive power margin is Q. i -Q min·i The positive transient reactive power margin is Q. max·i -Q i Under the condition that the total load of the grid-type converters with automatic fast response of reactive power / voltage in the entire power station remains unchanged, the optimal ratio K of reverse transient reactive power margin to forward transient reactive power margin is... x for:

[0089]

[0090] According to K x By plotting the PQ points corresponding to various load rates for x grid-type converters with automatic fast response to reactive power / voltage, the optimal location of the PQ point for the grid-type converter can be obtained. By plotting the PQ point locations corresponding to different load rates, the range of optimal PQ point locations can be obtained.

[0091] Set the optimal region boundary of the PQ point of the grid-type converter: Draw the optimal region boundary of the PQ point of the grid-type converter near the optimal position of the PQ point of the aforementioned transient reactive power grid-type converter. Under normal conditions, when the PQ points of all x transient reactive power grid-type converters in the station are within the optimal region boundary range of the PQ point of the grid-type converter, it can ensure that the overall reverse and forward transient reactive power margins of the x transient reactive power grid-type converters in the station are maximized.

[0092] S9. Under normal conditions, all transient reactive power grid-type converter PQ points in the monitoring station should operate within the optimal area boundary of the grid-type converter PQ point. If the transient reactive power grid-type converter PQ point exceeds this range, an early warning will be issued to remind maintenance personnel to handle the situation in a timely manner.

[0093] Specifically, under normal operating conditions, such as Figure 6 As shown, by monitoring whether the PQ points of x transient reactive power grid-type converters in the monitoring station are all operating within the optimal range of the PQ point boundary of the grid-type converter, if the PQ points of individual transient reactive power grid-type converters exceed this range, an early warning will be issued, and maintenance personnel will be reminded to handle it in a timely manner.

[0094] S10. Under normal conditions, the optimal region boundary of the PQ point of the grid-type converter should operate within the safety domain boundary of the transient reactive power PQ of the grid-type converter. If it exceeds this range, an early warning will be issued to remind the operation and maintenance personnel to handle it in a timely manner.

[0095] Specifically, under normal operating conditions, such as Figure 6As shown, the monitoring system checks whether the optimal region boundary of the PQ point of the grid-type converter is within the safety domain boundary of the transient reactive power PQ of the grid-type converter. If it exceeds this range, an early warning is issued, and maintenance personnel are reminded to handle it in a timely manner.

[0096] S11. Draw the safety zone boundary of the reactive power generation equipment PQ. The vertical and horizontal directions are the active and reactive directions, respectively. The vertical coordinate of point PQ is in the per-unit value of active power. The position of point PQ of the reactive power generation equipment at the safety zone boundary of the reactive power generation equipment PQ: The vertical coordinate of point PQ is the per-unit value of active power (0). The horizontal position of point PQ is determined by the ratio of its reverse and forward reactive power adjustable margins.

[0097] Specifically, a common PQ rectangular coordinate system is set up for the PQ group, and the safety domain boundary of each reactive power generation device PQ point is drawn on the PQ rectangular coordinate system to form the safety domain boundary of the reactive power generation device PQ group, and to determine the position of each reactive power generation device PQ point in the PQ rectangular coordinate system.

[0098] For example, such as Figure 7 As shown, the safety domain boundary of the reactive power generation equipment PQ group is set. For the active power P of the jth reactive power generation equipment i Given the given conditions, point PQ is located. A horizontal line is drawn through point PQ. Intersect the reactive power lower limit boundary of the PQ group security domain at point. Intersect the reactive power upper limit boundary of the PQ group security domain at point

[0099] The following formula can be obtained through calculation:

[0100]

[0101] In the formula, line segment E min·j E j and line segment E j E max·j Let P and Q be the reverse reactive power adjustable margin and the forward reactive power adjustable margin of the j-th reactive power generator, respectively. The above formula indicates the operating point PQ of the j-th reactive power generator. Reactive power limit to the PQ group safety domain boundary and reactive power limit The ratio of the distance to the reverse reactive power adjustable margin E of the grid-type converter min·j E j and positive reactive power adjustable margin E j E max·j The ratios are equal.

[0102] S12, select a group of reactive power generation devices in the field station that can provide transient reactive power, calculate the reverse and forward transient reactive power margin ratio of each transient reactive power generation device, wherein the minimum value and the maximum value of the reverse and forward transient reactive power margin ratio determine the size of the reverse and forward transient reactive power margin of the group of transient reactive power generation devices.

[0103] Specifically, there are y sets of transient reactive power generation devices with automatic fast response of reactive power / voltage in the new energy field station, and the ratio of the reverse and forward transient reactive power margin of the jth set of transient reactive power generation devices is K i :

[0104]

[0105] The ratio of the reverse and forward transient reactive power margin of the first to the yth set of transient reactive power generation devices is K1, K2, … K j , … K y , wherein the minimum value is K ymax , and the maximum value is K ymax .

[0106] Then the reverse transient reactive power margin of the group of y sets of transient reactive power generation devices in the new energy field station is:

[0107]

[0108] The forward transient reactive power margin of the group of y sets of transient reactive power generation devices in the new energy field station is:

[0109]

[0110] Wherein, ∑Q y- , ∑Q y+ are the reverse and forward transient reactive power margin of the group of y sets of transient reactive power generation devices in the field station;

[0111] K ymax , K ymin are the maximum and minimum values of the reverse and forward transient reactive power margin ratio of the y sets of transient reactive power generation devices in the field station;

[0112] Q min·j , Q max·j are the lower and upper limits of the reactive power of the jth set of transient reactive power generation devices.

[0113] S13, set the transient reactive power PQ safety domain boundary of the reactive power generation device within the PQ safety domain boundary of the reactive power generation device, calculate the optimal position of the PQ point of the reactive power generation device, and set the boundary of the optimal area of the PQ point of the reactive power generation device.

[0114] Transient reactive power PQ safety domain boundary of the reactive power generation equipment: when the reactive power generation equipment PQ group operates within the transient reactive power PQ safety domain boundary of the reactive power generation equipment, it can ensure that a certain reverse and forward transient reactive power is reserved in various states, and the reactive power generation equipment group in the station can provide a certain transient reactive power support for voltage stability during system disturbance or fault process, and all PQ points of the reactive power generation equipment group can enter a new stable state after fault removal without exceeding the reactive power generation equipment PQ safety domain boundary.

[0115] Specifically, the optimal position of the reactive power generation equipment PQ point is calculated: first, the optimal ratio of the reverse transient reactive power margin and the forward transient reactive power margin of the reactive power generation equipment in the station is calculated, which is the ratio of the sum of the reverse transient reactive power margin of all transient reactive power generation equipment in the station to the sum of the forward transient reactive power margin of all transient reactive power generation equipment in the station. According to the optimal ratio of the reverse transient reactive power margin and the forward transient reactive power margin of the station, the optimal PQ point of the transient reactive power generation equipment is drawn, and all optimal PQ points form the optimal position of the transient reactive power generation equipment PQ point.

[0116] For example, suppose there are y units of transient reactive power generation equipment in a certain station, and the hth unit of reactive power generation equipment operates at a PQ point of E j (Q j , P j ), the reverse transient reactive power margin is Q j -Q min·j , and the forward transient reactive power margin is Q max·j -Q j , then the optimal ratio K y of the reverse transient reactive power margin and the forward transient reactive power margin of the station as a whole is:

[0117]

[0118] According to the value of K y , the PQ points corresponding to various load rates of the y units of transient reactive power generation equipment are drawn, and the optimal position of the reactive power generation equipment PQ point is obtained. By drawing the PQ point position corresponding to different load rates, the optimal position range of the PQ point is obtained.

[0119] Set the optimal region boundary of the reactive power generation equipment PQ point: draw the optimal region boundary of the reactive power generation equipment PQ point near the optimal position of the transient reactive power generation equipment PQ point described above. Under normal conditions, when all transient reactive power generation equipment PQ points in the station enter the optimal region boundary range of the reactive power generation equipment PQ point, it can ensure that the reverse and forward transient reactive power margins of the entire transient reactive power generation equipment in the station are maximized.

[0120] S14, in normal state, all transient reactive power generation equipment PQ points in the field station should be operated in the optimal region boundary range of the reactive power generation equipment PQ point, and if the transient reactive power generation equipment PQ point exceeds this range, a warning is given to remind the operation and maintenance personnel to handle it in time.

[0121] Specifically, in normal operation state, whether the PQ points of the y-table transient reactive power generation equipment in the field station are all operated in the optimal region boundary range of the reactive power generation equipment PQ point is monitored, and if the PQ point of an individual transient reactive power generation equipment exceeds this range, a warning is given to remind the operation and maintenance personnel to handle it in time.

[0122] S15, in normal state, the optimal region boundary of the reactive power generation equipment PQ point should be operated in the transient reactive power PQ safety domain boundary of the reactive power generation equipment, and if it exceeds this range, a warning is given to remind the operation and maintenance personnel to handle it in time.

[0123] Specifically, in normal state, the optimal region boundary of the reactive power generation equipment PQ point should be operated in the transient reactive power PQ safety domain boundary of the reactive power generation equipment, and if it exceeds this range, a warning is given to remind the operation and maintenance personnel to handle it in time.

[0124] S16, preventive control of transient reactive power of field station overall power generation element.

[0125] First, the transient reactive power construction network type converter group and the transient reactive power generation equipment group are optimized and controlled respectively;

[0126] Further, the transient reactive power of the transient reactive power construction network type converter group and the transient reactive power generation equipment group in the field station is coordinated, so that the optimal ratio of the reverse transient reactive power margin and the forward transient reactive power margin of the transient reactive power construction network type converter group in the field station is equal to the optimal ratio of the reverse transient reactive power margin and the forward transient reactive power margin of the transient reactive power generation equipment group in the field station.

[0127] Specifically, in normal operation state of the field station,

[0128] 1) First, the transient reactive power construction network type converter group and the transient reactive power generation equipment group are optimized and controlled respectively;

[0129] 2) Further, the transient reactive power of the transient reactive power construction network type converter group and the transient reactive power generation equipment group in the field station is coordinated, so that the optimal ratio of the reverse transient reactive power margin and the forward transient reactive power margin of the transient reactive power construction network type converter group in the field station is equal to the optimal ratio of the reverse transient reactive power margin and the forward transient reactive power margin of the transient reactive power generation equipment group in the field station. x K y K x = K y , if the following abnormal conditions occur in the adjustment process, corresponding disposal is carried out.

[0130] S17, the whole power station transient reactive power element early warning. When the transient reactive power element PQ point optimal region boundary exceeds its transient reactive power PQ safety domain boundary, early warning, remind the operation and maintenance personnel to deal with in time; when the transient reactive power network type converter and the transient reactive power generation equipment optimal ratio difference is greater than the threshold value, early warning, and the corresponding disposal, A is a given threshold value.

[0131] Specifically, the following steps are included:

[0132] 1. As shown in Figure 6 When the transient reactive power network type converter PQ point optimal region boundary exceeds the transient reactive power PQ safety domain boundary of the network type converter, early warning, remind the operation and maintenance personnel to deal with in time;

[0133] 2. Or as shown in Figure 8 The transient reactive power generation equipment PQ point optimal region boundary exceeds the transient reactive power PQ safety domain boundary of the reactive power generation equipment, early warning, remind the operation and maintenance personnel to deal with in time;

[0134] 3, when |K x -K y |>A alarm, and the corresponding disposal, A is a given threshold value.

[0135] The above three cases can adopt the following disposal method:

[0136] 1. By increasing or reducing the voltage of the upper power grid, the normal state of the power station is restored;

[0137] 2. Or by changing the main transformer tap changer method, the normal state of the power station is restored.

[0138] S18, the whole power station transient reactive power coordination management.

[0139] Specifically, on the one hand, the transient reactive power reverse and forward margin ratio of the converter PQ group and the reactive power generation equipment PQ group in the power station is equal.

[0140] On the other hand, through the coordination management of the operation mode, parameter given, short circuit ratio, load rate and other factors of the power element automatic regulating device, when the system voltage is disturbed or fails, the moving speed of all PQ points of the transient network type converter PQ group and the transient reactive power generation equipment PQ group of the present application is equal or almost equal.

[0141] It should be noted that the above transient reactive power coordination control measures are in ideal state, that is, when the system state changes or fails, the converter or reactive power generation equipment that can provide transient reactive power, all PQ points are in Figure 3 The converter PQ group safety domain and Figure 5 The reactive power generation equipment PQ group safety domain, the moving speed of all PQ points is equal.

[0142] In fact, the PQ point moving speed and the power generation element automatic adjusting device design operation mode, parameter given, and the power generation element short circuit ratio, load rate and other factors are related, and the coordination of the field station transient reactive power also needs the coordination of the transient reactive power adjusting speed.

[0143] Satisfying the above two aspects can guarantee the coordination of the field station overall transient reactive power and ensure the maximum of the field station overall bidirectional transient reactive power.

[0144] It should be noted that the present application only considers the new energy field station, and the transient reactive power thereof is provided by the network type converter and the reactive power generation equipment, other conditions, such as the converter station, and the transient reactive power thereof is provided by the network type converter, the reactive power generation equipment, the large-scale thermal power unit, the transformer substation and the like, in theory, the same reasoning can be made, the transient reactive power measurement and the optimization control of the converter station can be carried out, and the present application will not be described in detail.

[0145] The above is only the preferred embodiment of the present application, and it should be pointed out that for ordinary skilled persons in the technical field, a number of improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. An optimization method for bidirectional transient reactive power measurement in new energy power plants, characterized in that, Includes the following steps: S1. Classify grid-type converters and other reactive power generation equipment with voltage change / reactive power automatic adjustment response capabilities in the power station as reactive power generation elements, and define the reactive power generated by reactive power generation elements with voltage change / reactive power rapid automatic adjustment response capabilities in the power station as transient reactive power. S2. Set up a rectangular coordinate system PQ for the reactive power generation element, where the P-axis is arranged vertically and the Q-axis is arranged horizontally. Draw the safety boundary of the power generation element PQ on the rectangular coordinate system PQ, and draw the reactive power generation element PQ point on the rectangular coordinate system PQ. Draw a horizontal line through the PQ point, intersecting the lower limit and upper limit of the PQ safety boundary at two points. The area between the two points is the reactive power adjustable range of the power generation element. The distance from the PQ point to the lower limit intersection point of the PQ safety boundary is the reverse reactive power adjustable margin, and the distance from the PQ point to the upper limit intersection point of the PQ safety boundary is the forward reactive power adjustable margin. S3. When the reactive power generation element is put into the terminal voltage change / reactive power fast automatic tracking adjustment mode, its reverse and forward reactive power adjustable margins are regarded as the reverse and forward transient reactive power margins of the power generation element, respectively. S4. Draw the safety domain boundary of the reactive power generation element PQ, and determine the position of the reactive power generation element PQ point within the PQ safety domain boundary. S5. Divide the power generation components in the station that have the ability to quickly and automatically adjust voltage changes / reactive power into a transient reactive power generation component group. S6. Select transient reactive power generation elements that can provide transient reactive power within the power station to form a group, calculate the ratio of reverse transient reactive power margin to forward transient reactive power margin for each transient reactive power generation element, obtain the minimum and maximum values ​​of the ratio of reverse transient reactive power margin to forward transient reactive power margin, and obtain the reverse transient reactive power margin and forward transient reactive power margin of the transient reactive power generation element group based on the minimum and maximum values. The ratio of the reverse transient reactive power margin to the forward transient reactive power margin of the transient reactive power generation element is: K i E is the ratio of the reverse transient reactive power margin to the forward transient reactive power margin. i Point PQ is the transient reactive power generation element; E min·i E is the intersection of point PQ of the transient reactive power generation element and the lower boundary limit of the PQ safety boundary. max·i The point where the transient reactive power generation element PQ point intersects with the upper limit of the PQ safety boundary; Wherein, the reverse transient reactive power margin of the transient reactive power generation element group is: The positive transient reactive power margin of the transient reactive power generation element group is: ∑Q x- ,∑Q x+ These represent the reverse and forward transient reactive power margins of x transient reactive power generation element groups within the power station; K xmax K xmin These represent the maximum and minimum values ​​of the reverse and forward transient reactive power margin ratios for x transient reactive power generation elements within the power station; Q min·i Q max·i These are the lower and upper limits of reactive power for the i-th transient reactive power generation element, respectively. S7. Set the transient reactive power PQ safety domain boundary of the reactive power generation element within the PQ safety domain boundary and calculate the optimal position of the PQ point of the reactive power generation element. Set the optimal region boundary of the PQ point of the reactive power generation element according to the optimal position of the PQ point. S8. Under normal operating conditions, monitor whether all transient reactive power generation element PQ points in the monitoring station are operating within the optimal region boundary of the transient reactive power generation element PQ point. If the transient reactive power generation element PQ point exceeds the optimal region boundary of the PQ point, an early warning will be issued and measures will be taken. Monitor whether the optimal region boundary of the transient reactive power generation element PQ point is operating within the transient reactive power PQ safety domain boundary. If the optimal region boundary of the PQ point exceeds the transient reactive power PQ safety domain boundary, an early warning will be issued and measures will be taken.

2. The optimization method for bidirectional transient reactive power measurement of a new energy power station according to claim 1, characterized in that: In step S2, the safety boundary of the transient reactive power generation element PQ is determined based on the operating parameters of the transient reactive power generation element.

3. The optimization method for bidirectional transient reactive power measurement of a new energy power station according to claim 1, characterized in that: In step S4, the position of the reactive power generation element PQ point is: The vertical coordinate of the reactive power generation element PQ point is the per-unit value of the active power, and the horizontal coordinate of the reactive power generation element PQ point is determined by the ratio of its reverse and forward reactive power adjustable margin.

4. The optimization method for bidirectional transient reactive power measurement of a new energy power station according to claim 3, characterized in that: The reverse and forward reactive power adjustable margin ratios of the reactive power generation element PQ point are: in, For the i-th reactive power generation element in active power P i PQ point under the given conditions; and These are the lower and upper reactive power limits of the PQ group's security domain boundary, respectively; E min·i E i and E i E max·i These represent the reverse reactive power adjustment margin and the forward reactive power adjustment margin of the i-th reactive power generation element, respectively.

5. The optimization method for bidirectional transient reactive power measurement of a new energy power station according to claim 1, characterized in that: In step S6, the optimal ratio K of the reverse transient reactive power margin and the forward transient reactive power margin of the overall transient reactive power generation element is determined. z for: Where n is the number of transient reactive power generation components operating in the power station, and Q k Let Q be the x-coordinate of point PQ where the k-th transient reactive power generation element is operating. min.k Let Q be the x-coordinate of the intersection of the PQ point of the power generation element and the minimum reactive power limit of the maximum operating boundary. max.k The x-coordinate of the intersection of the PQ point of the power generation element and the maximum operating boundary reactive power limit.

6. The optimization method for bidirectional transient reactive power measurement of a new energy power station according to claim 1, characterized in that: In step S7, the boundary of the transient reactive power PQ security domain is: When the reactive power generation element PQ group operates within the transient reactive power PQ safety domain boundary of the reactive power generation element, it can ensure that a certain amount of reverse and forward transient reactive power can be reserved in various states. During system disturbances or faults, the reactive power generation element group in the station can provide a certain amount of transient reactive power support voltage stability, and all PQ points of the reactive power generation element group do not exceed the reactive power generation element PQ safety domain boundary, and can enter a new stable state after the fault is cleared.

7. The optimization method for bidirectional transient reactive power measurement of a new energy power station according to claim 1, characterized in that: In step S8, the treatment method includes the following steps: Increase or decrease the voltage of the upstream power grid to restore the station to normal operation; Alternatively, the station can be restored to normal operation by changing the main transformer tap changer.

8. A method for coordinating transient reactive power generation components in a new energy power station, comprising a grid-type converter group composed of multiple grid-type converters and a reactive power generation equipment group composed of multiple reactive power generation devices, wherein the grid-type converter group and the reactive power generation equipment group are optimized by the bidirectional transient reactive power measurement optimization method for new energy power stations as described in claim 1, characterized in that: Includes the following steps: Calculate transient reactive power and optimal region separately for each group; An alarm is triggered when the difference between the optimal ratio of reverse and forward transient reactive power margins of the grid-type converters and the transient reactive power generation equipment exceeds a given threshold. The system is then adjusted to make the optimal ratio of reverse and forward transient reactive power margins of the grid-type converter group within the power station equal to the optimal ratio of reverse and forward transient reactive power margins of the reactive power generation equipment group within the power station, thereby maximizing the overall reverse and forward transient reactive power margins of the power station.

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