An Improved Frequency Dead Zone with Feed-Forward Control for Hydropower Units: Performance Evaluation of Primary Frequency Control

Abstract

Due to the integration of more intermittent renewable energy into the power grid, the demand for frequency control in power systems has been on the rise, and primary frequency control of hydropower units plays an increasingly important role. This paper proposes an improved frequency dead zone with feed-forward control. The aim is to achieve a comprehensive performance of regulating rapidity, an assessment of integral quantity of electricity, and the wear and tear of hydropower units during primary frequency control, especially the unqualified performance of integral quantity of electricity assessment under frequency fluctuations with small amplitude. Based on a real hydropower plant with Kaplan units in China, this paper establishes the simulation model, which is verified by comparing experimental results. After that, based on the simulation of real power grid frequency fluctuations and a real hydropower plant case, the dynamic process of primary frequency control is evaluated for three aspects, which include speed, integral quantity of electricity, and wear and tear. The evaluation also includes the implementations of the three types of dead zones: common frequency dead zone, the enhanced frequency dead zone, and the improved frequency dead zone. The results of the study show that the improved frequency dead zone with feed-forward control increases the active power output under small frequency fluctuations. Additionally, it alleviates the wear and tear problem of the enhanced frequency dead zone in the premise of guaranteeing regulation speed and integral quantity of electricity. Therefore, the improved frequency dead zone proposed in this paper can improve the economic benefit of hydropower plants and reduce their maintenance cost. Accordingly, it has been successfully implemented in practical hydropower plants in China.

Experimental Study on the Optimal Strategy for Power Regulation of Governing System of Hydropower Station

“…Guo and Yang [28] established nonlinear state equations for the opening control and the power control mode and investigated the performance of PFR (Primary Frequency Regulation) under different control modes. An et al [29] and Fu et al [30,31] researched the dynamic performance of PFR in the opening control mode and power control mode and developed a method to improve the regulating ability. In [32,33], some optimal strategies were proposed to improve the regulating ability and quality in the power control mode.…”

Characteristic Analysis and Optimal Regulation of Primary Frequency Regulation Condition in Low Water Head Area Based on Hydraulic-Mechanical-Electrical Coupling Model of Pumped Storage Unit

“…e frequency regulation function of PSU is very important to maintain the stability of power grid frequency, especially for those power grids with small proportion of prompt adjustment units [5]. An et al proposed an improved frequency dead zone with feed-forward control to optimize the frequency regulation function of PSU [6]. Yang and Yang and Zhao and Ren also studied the role of pumped storage units in enhancing power system stability and frequency control [7,8].…”