This paper investigates an interference mitigation technique for dynamic time division duplex (TDD) based frequency-separated small cell networks in future long term evolution advanced (LTE-A) based wireless access systems. In dynamic TDD, cross-link interference, i.e. evolved node B (eNB)-eNB interference and user equipment (UE)-UE interference, also occur, and eNB-eNB interference in particular significantly degrades the uplink (UL) transmission performance. In order to alleviate the impacts of eNB-eNB interference and to obtain high traffic adaptation gain, we investigate a transmit power control (TPC) based interference mitigation (IM) scheme. In TPC-IM, time-domain subframes are divided into two subframe sets according to whether the cross-link interference can occur or not, and different TPC parameters are applied depending on the type of subframe. To improve of UL signal to interference plus noise power ratio (SINR) in the subframe set with the potential to occur eNB-eNB interference, there are two approaches of UL power boosting and downlink (DL) power reduction. We investigate the adequate combination of these two approaches to avoid an impact of DL performance degradation and increase of UE power consumption. Moreover, we further investigate a combined scheme of the TPC-IM and a cell clustering interference mitigation (CCIM) to avoid the significantly strong cross-link interference from the neighbouring cells. Computer simulation confirms that the proposed TPC-IM scheme can achieve 4.4% and 26.2% gain in the average DL and UL throughputs, respectively, compared to the case without any IM schemes on dynamic TDD. Moreover, when the CCIM is applied to the TPC-IM scheme, 11.6% and 40.3% gain can be achieved in the average DL and UL throughputs, respectively.