Maintaining frequency is crucial for the security of power systems, while deep cyber–physical interactions make frequency regulation susceptible to cyber-attack risks. False data injection (FDI) attacks, denial-of-service (DoS) attacks, and latency attacks are typical types of cyber-attacks prevalent in power systems, each capable of deteriorating system frequency through distinct mechanisms and posing serious security risks. However, existing studies on frequency regulation lack security aspects that can comprehensively address all these attack types. To fill this gap, this paper investigates a security strategy to safeguard power system frequency regulation. First, considering all these attacks, the system frequency regulation system is modeled to reveal the severity of cyber-security problems, specifically the failure to maintain frequency due to cyber-attacks. Moreover, a cyber-resilient control (CRC) strategy is developed to counter FDI, DoS, and latency attacks comprehensively. The CRC strategy involves a two-step process, including a safety surface and auxiliary trajectory control. The safety surface serves as a defensive barrier against multiple cyber-attacks, while the auxiliary trajectory control activates the safety surface's defense capability, thereby ensuring the security of system frequency. Furthermore, rigorous proofs are given based on Lyapunov theorem, demonstrating that system stability can be guaranteed by the developed CRC strategy, even under multiple types of cyber-attacks. Finally, test results confirm the efficacy of the CRC strategy. For instance, it prevents pre-existing frequency oscillations and destabilization, and also reduces the maximum frequency deviation by approximately 96.61% under multiple cyber-attacks. Therefore, the developed CRC strategy can comprehensively defend against FDI, DoS, and latency cyber-attacks, significantly contributing to the power system security.