JP2009217762A - Controller of power transducer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control means which provides an operation amount as an operation command value also in an operation area except a power transducer operation rated point or a reference point. <P>SOLUTION: This controller of a power transducer provides each control system input of constant current control (ACR) and constant voltage control (AVR) with a bias value as a setting value, and reduces steady-state deviation in feedback control of primary lead delay control or primary delay control. Furthermore, the controller of the power transducer calculates, by automatic calculation, the bias value to be provided to each control system input of the constant current control (ACR) and the constant voltage control (AVR) as a linear function based on the fact that the bias value is proportional to a power instructed value (Pdp), a DC current instructed value (Idp) and a DC voltage instructed value (Vdp). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a control device in a power converter, and more particularly, to a control device using a feedback control method of primary delay control or primary advance delay control for constant current control or constant voltage control, and a control device related thereto.

  When feedback control is used in a conventional power converter control method, it is often configured with a first-order advance-delay type. This is because the integration system control has problems at the present time such as being easily affected by ripple current because the current margin does not increase even when the control angle of the power converter increases. When the feedback control is configured in the primary advance / delay type, the operating power command value and the actual operating power do not completely coincide with each other in order to generate a steady deviation. Normally, in order to correct this steady deviation, a bias value (fixed value) is input to each ACR and AVR control system input so that a rated output is obtained at the rated operating point. The bias value to be added to the control system input is set so that the rated output is obtained at the rated operating point.The calculation of this bias value is based on the operating quantities of the equipment that constitutes the power converter and the rated operating point. The theoretical set value was calculated from the relationship between the control amount (control angle) that can be derived under various conditions such as equipment loss and the control system gain. For this reason, since the bias value is added to the steady deviation as the operation point deviates from the rated point, there is a problem that the operation command value and the actual operation power do not match. Japanese Unexamined Patent Publication No. 58-75224 is known as the above prior art.

JP 58-75224 A

  Conventionally, since the bias value was set during rated operation, there was a problem that an operation amount equal to the operation command value could not be obtained at an operation point deviating from the rated point.

  An object of the present invention is to provide a control means capable of obtaining an operation amount according to an operation command value even in an operation region other than a rated point or a reference point.

  In order to achieve the above object, the power converter control device of the present invention gives a bias value as a set value to each control system input of constant current control (ACR) or constant voltage control (AVR), and performs primary advance / delay control. Alternatively, the steady-state deviation in the feedback control of the first-order lag control is reduced.

  Further, the control device for the power converter according to the present invention provides a bias value given to each control system input of constant current control (ACR) and constant voltage control (AVR) as a power command value (Pdp) and a direct current command value (Idp). , Is calculated by automatic calculation as a linear function based on being proportional to the DC voltage command value (Vdp).

  Since the control device of the present invention can correct the theoretical bias value according to the operation command value with respect to the feedback control, there is an effect that a control amount (operation amount) having a small deviation from the operation power command value can be obtained. .

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 2 is a block diagram showing an example of the main circuit configuration and control method of the power converter. The power converter 31 is connected to the AC system 11 via the conversion transformer 21, and the power converter 32 is connected to the AC system 12 via the conversion transformer 22. The power converters 31 and 32 are connected via DC transmission lines 51 and 52, and DC reactors 41 and 42 are provided in the line of the DC transmission line 51.

  In FIG. 2, the main circuit configuration example of the direct current power transmission (HVDC) facility is shown. However, in the different system direct current link (FC, BTB) facility, the direct current transmission lines 51 and 52 are not connected, but the direct current reactor is connected through one DC reactor. It becomes the composition to be done.

  Each power converter is a separately-excited converter that uses a thyristor as a semiconductor element. The thyristor is turned on and off in accordance with an ignition signal given from the control device, and AC power is converted to DC power or DC power is converted. Convert to AC power.

  FIG. 2 shows a case where the power converter 31 is a forward converter that converts AC power into DC power and the power converter 32 is an inverse converter that converts DC power to AC power as an example.

  The closed circuit between the power converter 31 that is a forward converter and the power converter 32 that is an inverse converter is a DC circuit, and a DC current detection value (Id) 61 that flows in the thyristor conduction direction, The DC power (Pd) is determined by the DC voltage detection value (Vd) 62 output from the power converter.

  The DC power (Pd) is controlled by the power setting unit (Pdp) 70 so as to become the set DC power.

  The power setting unit (Pdp) 70 generates a DC current command value (Idp) and a DC voltage command value (Vdp) based on the set power command value, and controls the forward converter side and the reverse converter side control devices. Output.

  In FIG. 2, a DC current command value (Idp) 81 is shown on the forward converter side, and a DC voltage command value (Vdp) 82 is shown on the reverse converter side, but the command value itself is shown on the forward converter side and the reverse converter. Idp and Vdp are output to the respective sides.

  Usually, the control system of the power converter is configured to control DC power by selecting and executing constant current control (ACR) on the forward converter side and selecting and executing constant voltage control (AVR) on the reverse converter side. . In FIG. 2, constant current control (ACR) 71 is shown on the forward converter side, and constant voltage control (AVR) 72 is shown on the reverse converter side, but the control circuit itself is on the forward converter side and the reverse converter side. Each of the ACR and AVR control systems is implemented.

  The constant current control (ACR) 71 in FIG. 2 subtracts the direct current command value Idp81 from the direct current detection value Id61 and adds a direct current bias value 91 as shown in FIG. It is used as an input for the advance / delay control circuit. The DC current bias value 91 is conventionally a fixed value input and is generally adjusted at the rated operating point. For this reason, since the bias value is added to the steady deviation as the operating point deviates from the adjustment point, there is a problem that the current command value does not match the actual operating current.

  In the present invention, by adding the bias correction circuit 101 in FIG. 1, the steady-state deviation is reduced by changing the DC current bias value 91 from the conventional fixed value input to the theoretical bias value input corresponding to the DC current command value Idp81. To do.

  The bias correction circuit 101 is given in advance the slope a and intercept b obtained by linear approximation from the relationship between each operating power and the theoretical bias value as set values, and the direct current command value Idp81 is a linear function of the input. The automatic calculation result is added to the control circuit as a direct current bias value 91. Thereby, it is possible to set the bias value according to the operating point.

  Similarly, the bias value of constant voltage control (AVR) can also be a function of Vdp, and a control circuit with a correction circuit is shown in FIG.

  As shown in FIG. 3, constant voltage control (AVR) primary delay control is performed by adding a DC voltage command value Vdp82 from the DC voltage detection value Vd62 and further subtracting a DC voltage bias value 92, which is an automatic calculation result of the bias correction circuit 102. Steady deviation can be reduced by using the circuit as an input.

  The method of the inclination a and the intercept b set in advance is generally calculated from a theoretical bias value obtained from a calculation formula for various operating quantities.

  The theoretical bias value is a value that corrects the steady-state deviation that occurs when the feedback control system is originally configured in the first-order lag type or first-order lag type, and the operation quantities for calculation are the converter control angle α, the transformation transformer It is constituted by elements such as a secondary voltage E2, a transformer impedance IX for conversion, a voltage drop VLoss due to equipment loss, a converter bridge stage number ns, a control system feedback loop gain GACR or GAVR. This operating quantity includes elements proportional to the operating power, such as equipment loss, and the theoretical bias value and the operating power (operating power command value) are in a proportional relationship. a and intercept b can be calculated in advance.

  The relational expression between the operation quantities and the theoretical bias value is shown below.

  The theoretical bias values IdB and VdB can be obtained by iterative calculation using equations (1) to (5).

(1) Forward converter side operation quantities

(2) Reverse conversion side operation quantities

α: Converter control angle, γ: Converter margin angle, u: Overlap angle E2: Transformer transformer secondary voltage, ns: Converter bridge series stage IX: Transformer impedance for conversion, VLoss: Voltage drop due to equipment loss GACR: ACR control feedback loop gain GAVR: AVR control feedback loop gain Id: DC current, Vd: DC voltage Idp: DC current command value, Vdp: DC voltage command value IdB: DC current theoretical bias value, VdB: DC voltage theoretical bias value

  FIG. 4 shows a case in which a steady deviation (Idd and Id deviation ΔId) between the operation command value and the operation amount is given as a fixed value (without a correction circuit) and an automatic calculation value (with a correction circuit) in the ACR control system. This is shown as an example in which the deviation amounts are compared.

  The deviation ΔId between the operation command value Idp and the control output Id is adjusted so that there is no error at the rated point of 1 pu.

  When there is no correction circuit, there is an error of about + 0.7% in ΔId at the minimum operating point of 0.1 pu, but this ΔId curve is linearly approximated as a dotted line, and a correction circuit is added as a linear function. In this case, the deviation ΔId can be reduced to 0.1% or less.

  In a system in which the operation command value changes in real time during operation of the power converter, the response of the theoretical bias value to the transient change of the command value must be coordinated with constant current control (ACR) or constant voltage control (AVR). There is.

  This is because the theoretical bias value is directly input to the feedback control circuit, so that the constant current control (ACR) or the constant voltage control (AVR) responds to a transient change in the theoretical bias value, and an unstable phenomenon due to control interference. Because there is a fear of.

  The theoretical bias value is for the purpose of correcting the steady-state deviation when the control is stable, and the response to the transient change is preferably slower than the constant current control (ACR) or the constant voltage control (AVR). After constant current control (ACR) or constant voltage control follows, it is necessary to correct the deviation due to the theoretical bias value.

  FIG. 5 is obtained by adding a first-order lag circuit for preventing a transient response to the direct current command value (Idp) input to the constant current control (ACR) correction circuit of FIG.

  By making the delay time constant of the primary delay circuit sufficiently larger than the delay time constant of constant current control (ACR), the bias correction circuit of the bias correction circuit can be adapted to a sudden change in the DC current command value (Idp). The response of the theoretical bias value, which is the calculation result, can be corrected with a sufficient delay and can prevent instability due to control interference, so it can be applied to systems where the operation command value changes in real time. .

The figure which shows the Example (constant current control ACR) of this invention. The figure which shows an example of the power conversion system of embodiment of this invention. The figure which shows the Example (constant voltage control AVR) of this invention. The figure which shows the example of an effect of this invention. The figure which shows the Example (constant current control ACR) which added the transient response prevention function.

Explanation of symbols

11, 12 AC system 21, 22 Conversion transformer 31, 32 Power converter 41, 42 DC reactor 51, 52 DC transmission line 61 DC current detection value Id
62 DC voltage detection value Vd
70 Power setting device 71 Constant current control (ACR)
72 Constant voltage control (AVR)
81 DC current command value Idp
82 DC voltage command value Vdp
91 DC current bias value 92 DC voltage bias value 101, 102 Bias correction circuit 111 First order lag circuit (for transient response prevention)

Claims (2)

  A control device for a power converter that converts AC power into DC power or DC power into AC power, and includes a power command value (Pdp) and a DC current command value (Idp) or a DC voltage command value (Vdp) given from the power setter. ) In accordance with the control method of the power converter, in which the constant current control (ACR) and the constant voltage control (AVR) for power control are configured by the feedback control system of the primary advance / delay control or the primary delay control, By giving a bias value as a set value to each control system input of the constant current control (ACR) or the constant voltage control (AVR), the steady deviation in the feedback control of the primary advance / delay control or the primary delay control is reduced. The control apparatus of the power converter characterized by the above-mentioned.   2. The control apparatus for a power converter according to claim 1, wherein a bias value given to each control system input of the constant current control (ACR) or the constant voltage control (AVR) is the power command value (Pdp), the direct current A control device for a power converter, wherein a control function is calculated by automatic calculation as a linear function based on a command value (Idp) and proportional to the DC voltage command value (Vdp).

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