Method for controlling speed regulating system of hydroelectric unit in island mode

Abstract

The invention discloses a method for controlling a speed regulating system of a hydroelectric unit in an island mode. The speed regulating system of the hydroelectric unit is adjusted by using double-integral links. The method is characterized in that: according to the operating state of the hydroelectric unit, parameters in an integral formula are adjusted; when the hydroelectric unit normally operates, Ex in the formula is 0.5 Hz, and Bp is 4 percent; when the hydroelectric unit steadily operates in the island mode, the Ex in the formula is 0.5 Hz, and the Bp is equal to 1 percent; and when the hydroelectric unit dynamically operates in the island mode, the Ex in the formula is 0.1 Hz, and the Bp is less than or equal to 0.001 percent. Various kinds of regulation modes are connected in parallel; when a load of a system electric network highly fluctuates to cause high frequency fluctuation, a high-frequency proportion integration differentiation (PID) controller is adopted for closed-loop control; and when the hydroelectric unit steadily operates, the aim of micro and slow adjustment of the system is fulfilled by using a small integral mode. The method has the advantages that: the states and the parameters can be automatically switched without manual interference; automatic regulation is perfect; and a regulation effect is better.

Description

technical field [0001] The invention belongs to the technical field of electric power system automation, and in particular relates to a control method suitable for a speed regulating system of a hydroelectric unit in an island mode. Background technique [0002] At present, there are three control methods for the turbine speed control system of the hydroelectric unit to realize the unit frequency and power control: frequency mode, which means that the speed governor takes a certain frequency as the target value, and uses frequency feedback as the control logic of the feedback unit, and finally realizes The unit frequency meets the given requirement. For example, in the no-load state, the governor needs to maintain the set frequency to the given value, and the frequency dead zone Ex and the adjustment coefficient BP are both 0; for example, in the power generation state, the system frequency exceeds Ex, and the frequency regulation action participates in the regulation. The ...

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Problems solved by technology

However, the above scheme does not have a special island discrimination device to send a signal to the governor, and does not set the parameters in the island mode separately, so there is a big gap in the goal of normal operation of the island

At the same time, it is worth pointing out that in the current smart grid, according to the power generation and operation status of the unit, the stabilizing device will automatically complete machine or load shedding according to high or low frequency, and largely rely on external technical measures to complete the control of frequency and active load , the above technical solution uses the frequency change of the governor itself as a criterion to judge whether to enter the island and complete some conversions between the no-load state and the power generation state, which is unreasonable and has certain risks

In addition, this technical solution cannot solve the problems of power oscillation and phase modulation when multiple units are connected in parallel on the bus.

[0011] If it is a stand-alone unit with an isolated small load, the current processing strategy is generally to directly discard the grid-connected signal and put the governor in no-load mode. It can be used under the condition of a single unit with load, and it cannot solve the problems of power oscillation and phase modulation when multiple units are connected in parallel on the bus.

There is another way, that is, on the premise of knowing in advance that you want to enter the small network mode, manually switch the handle of the large network / small network on the governor site, and the program internally calls the Bp (difference coefficient) to a relatively small This is relatively rough, and due to the existence of the given active power Pgv, according to the differential adjustment characteristics, the unit must maintain a higher frequency to offset the effect of Pgv, and the frequency will be unstable, outside the critical point of the dead zone , there is a tendency to fluctuate in the direction of high frequency (there is only a tendency that will be pulled back by the control, but the frequency fluctuates greatly; the magnitude of the fluctuation is proportional to Pgv)

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